High-Speed Optical Transmitters with Phase Modulators

  • Digital Operation up to 12.5 Gb/s or 40 Gb/s
  • Integrated Phase Modulator with RF Driver Amplifier
  • Integrated Tunable C-Band, Tunable L-Band, or 1310 nm Laser
  • Accepts External Lasers from 1250 to 1610 nm


Optical Transmitter with
12.5 Gb/s Phase Modulator
and C-Band Laser

Touch-Panel Interface for Device Control

Related Items

Please Wait
Optical Transmitter Block Diagram
Click for Details

This block diagram shows the internal setup of the MX10C and MX40C series of high-speed optical transmitters. Thorlabs also offers Reference Transmitters based on intensity modulators.

Got Questions?

Our engineers and expertise are here for you!

Janis Valdmanis, Ph.D. Optics
Ultrafast Optoelectronics
General Manager

If you are not sure whether our catalog items meet your needs, we invite you to contact us. Or ask about a loan, so you can try them out for yourself, in your own lab. We can also support custom or OEM requirements you may have.

Just press the button, and we'll get back to you within the next business day.

Contact Me

All-in-One High-Speed Optical Transmitters Include:

  • All-in-One High-Speed Optical Transmitters Include:
    • Phase Modulator
    • RF Amplifier
    • Telecom-Grade Laser
    • Variable Optical Attenuator (VOA) for Automatic or Manual Power Control
  • Digital Operation
    • MX10C Series for Applications up to 12.5 Gb/s
    • MX40C Series for Applications up to 40 Gb/s
    • User-Adjustable RF Amplifier Output Swing
  • Integrated C-Band Tunable Laser, L-Band Tunable Laser, or 1310 nm Fixed-Wavelength Laser (Contact Tech Support to Substitute an 850 nm Fixed-Wavelength Laser)
  • Operation from 1250 to 1610 nm Using External Laser Source
  • Digital RF Amplifier with Amplitude and Eye-Crossing Controls
  • External Loop-Back Cables Support Custom Configurations
  • Control via Intuitive Touchscreen Interface or Remotely Using USB or RS-232 Connections
  • Custom Configurations Available by Contacting the Ultrafast Optoelectronics Team

Thorlabs' High-Speed Optical Transmitters provide fully integrated, user-configurable solutions for high-speed phase modulation of light. They are based on proven lithium niobate (LiNbO3) modulator technology driven by high-fidelity RF amplifiers. The MX10C and MX40C series are designed for digital applications, and the maximum voltage output swing of their limiting RF amplifiers is user-adjustable. The MX10C phase modulator series supports speeds of up to 12.5 Gb/s digital operation and up to 7 GHz when used in analog mode, while the MX40C series includes a phase modulator that supports speeds of up to 40 Gb/s digital operation and up to 20 GHz when used in analog mode.

Each optical transmitter has a built-in telecom-grade tunable (C- or L-band) or fixed-wavelength (1310 nm) laser. Variable optical attenuators (VOAs) and power monitors enable completely automatic output power control and stabilization. These instruments are ideal for use in either an R&D laboratory or in a manufacturing environment for creating optical links, performing experiments requiring fast optical modulation, or testing other components. These optical transmitters are well suited to phase-shift keying binary modulation formats including BPSK and DPSK.

The C-band laser of the MX10C and MX40C and the L-band laser of the MX10C-LB and MX40C-LB are tunable over a range of 1527.6 nm - 1565.5 nm (191.50 THz - 196.25 THz) and 1570.0 - 1608.8 nm (186.35 THz - 190.95 THz), respectively, on the ITU 50 GHz grid. A frequency offset option allows for fine tuning by ±30 GHz in increments of 1 MHz, and a dither feature for wavelength stabilization is available in both tunable internal laser options (see the Operation tab for more information). The internal 1310 nm fixed-wavelength laser of the MX10C-1310 and MX40C-1310 has a typical wavelength of 1310 nm, which is the center of the O-band. Instruments with an 850 nm fixed-wavelength laser are also available upon request (contact Tech Support).

For further flexibility, the laser source and modulator are connected with an external loop-back cable, which allows users to modulate their own 1250 to 1610 nm laser source. The laser input port uses polarization-maintaining (PM) PANDA fiber with light linearly polarized along the slow axis (aligned to the connector key) and can accept a maximum input power of 20 dBm (100 mW). Each fiber bulkhead accepts FC/PC connectors. For complete specifications, please see the Specs tab.

The MX10C series includes an external loop-back cable for the driver RF output and modulator RF input ports, which provides the opportunity to use an external driver, if desired (see the Front & Back Panels tab for details). The RF port on the MX10C series accepts SMA connectors, and the RF port on the MX40C series accepts 2.92 mm (K™) connectors. Please see Thorlabs' complete selection of microwave cables and adapters.

These instruments can be controlled in two ways. The simplest method is using the intuitive touchscreen interface, which gives the user complete control over all instrument functionality. These instruments can also be operated remotely via the RS-232 or USB ports on the back panel. The Operation tab describes the graphical user interface (GUI) and user-customizable features, while the Software tab provides a remote control user guide and a remote control software tool for download.

Thorlabs offers a large selection of transmitter instruments, please see the Selection Guide tab above for all of our options.

K™ is a trademark of Anritsu.

Key Specificationsa
Item # MX10C MX10C-LB MX10C-1310 MX40C MX40C-LB MX40C-1310
Max Bit Rate (Digital) 12.5 Gb/s 40 Gb/s
Analog Bandwidth (Small Signal) 7 GHz 20 GHz
Modulator Bandwidth (-3 dB) 10 GHz 35 GHz
Laser Type C-Band Tunable L-Band Tunable 1310 Fixed-Wavelength C-Band Tunable L-Band Tunable 1310 Fixed-Wavelength
Wavelength Range 1527.6 - 1565.5 nm 1570.0 - 1608.8 nm 1310 nm (Typical) 1527.6 - 1565.5 nm 1570.0 - 1608.8 nm 1310 nm (Typical)
Frequency Range 191.50 - 196.25 THz 186.35 THz - 190.95 THz - 191.50 - 196.25 THz 186.35 THz - 190.95 THz -
Intrinsic Linewidth 10 kHz (Typical)
15 kHz (Max)
2 MHz (Typical)
3 MHz (Max)
10 kHz (Typical)
15 kHz (Max)
2 MHz (Typical)
3 MHz (Max)
External Laserc Wavelength Range 1250 nm - 1610 nm
Internal Power Monitor Calibration Points 1310 nm, 1550 nm, and 1590 nm
  • For complete specifications, see the Specs tab.
  • C-band and L-band lasers are tunable in 50 GHz steps. An internal 850 nm fixed-wavelength laser is available for substitution upon request. Please contact Tech Support for details.
  • User-provided.

General System Specifications
Item # MX10C MX10C-LB MX10C-1310 MX40C MX40C-LB MX40C-1310
Amplifier Type Digital (Limiting)
Bit Rate (Maximum) 12.5 Gb/s 40 Gb/s
Internal Laser Laser Type C-Band Tunable L-Band Tunable 1310 nm Fixed-Wavelength C-Band Tunable L-Band Tunable 1310 nm Fixed-Wavelength
Wavelength Rangea 1527.6 - 1565.5 nm 1570.0 - 1608.8 nm 1310 nm (Typical) 1527.6 - 1565.5 nm 1570.0 - 1608.8 nm 1310 nm (Typical)
Output Power (Typ.) 13.5 dBm
External Laserb Wavelength Rangec 1250 nm - 1610 nm
Optical Input Power 20 dBm (Max); 22 dBm (Absolute Max)
Power Calibration Points 1310 nm, 1550 nm, and 1590 nm
Optical Extinction Ratio 13 dB (Typical Maximum)
Electrical Return Lossd -10 dB (Any RF Port, Typical)
Modulator Type Phase
Optical Insertion Loss (Typical)e 4.5 dB (1550 nm)
6.5 dB (1310 nm)
5.0 dB (1550 nm)
7.0 dB (1310 nm)
Internal Optical Fiber PM Ports: PM PANDA Fiber
SM Port: SMF-28-Compatible Fiber
Fiber Connectors FC/PC, 2.0 mm Narrow Key
  • C-band and L-band lasers are tunable in 50 GHz steps. An 850 nm fixed-wavelength laser can be substituted upon request: contact Thorlabs’ Tech Support.
  • User-Supplied
  • Using the modulator at another wavelength (e.g. visible light) may cause an increase in insertion loss and will void the warranty.
  • To the -3 dB Bandwidth
  • Laser IN to Optical OUT.
Digital (Limiting) RF Amplifier Specifications
Item # Prefix MX10C MX40C
Bit Rate (Maximum) 12.5 Gb/s 40 Gb/s
Amplifier RF Inputa,b 400 mV (Typical)
3.5 V (Max)
4 V (Absolute Max)
400 mV (Typical)
4 V (Max)
6 V (Absolute Max)
Amplifier RF Output Swing
3 V - 7 V
RF Amplifier Gain (Fixed) 34 dB 30 dB
Rise/Fall Timec 35 ps 8 ps
Low Frequency Cutoff 100 kHz
  • Peak to Peak
  • Input is AC-Coupled. Maximum DC input allowable is ±15 V for the MX10C series and ±10 V for the MX40C series.
  • Large Signal, Digital Response
Phase Modulator Specifications
Item # Prefix MX10C MX40C
Electro-optic Bandwidth (-3 dB) 10 GHz 35 GHz
RF Drive Voltage (Vπ)a 4.5 V 7.0 V
Modulator RF Inputb,c 5.5 V (Typical)
7 V (Max)
10 V (Absolute Max)
Insertion Loss 3.5 dB (1550 nm)
5.5 dB (1310 nm)
4.0 dB (1550 nm)
6.0 dB (1310 nm)
  • Peak to Peak Voltage at 1 GHz
  • Peak to Peak Voltage
  • This specification is quoted only for the MX10C series. The external loop-back between the output of the RF amplifier and the internal modulator is accessible to the operator on these units, but the connection is made directly inside the housing in the MX40C series.
Common Power Monitor and VOAa Specifications
Power Monitor Accuracyb ±0.5 dBm at Power Calibration Points
Power Monitor Resolutionb 0.01 dBm
Power Monitor Insertion Loss 0.1 dB (Typical) per Monitor
VOA Insertion Loss 0.4 dB (Typical)
VOA Response Time 1 s
  • Variable Optical Attenuator
  • Applies to each of the three internal power monitors.
Common Power and Environmental Specifications
Parameter Min Max
Main AC Voltage 100 VAC 250 VAC
Power Consumption - 60 VA
Line Frequency 50 Hz 60 Hz
Operating Temperature 10 °C 40 °C
Storage Temperature 0 °C 50 °C
Humiditya 5% Relative Humidity 85% Relative Humidity
  • Non-Condensing Environment
C-Band Laser Frequency Noise Spectrum
Click to Enlarge

FM Noise Spectrum of the integrated tunable laser. The dither function helps stabilize the wavelength. Turning the dither off provides for lower noise.
C-Band Tunable Laser Specifications (MX10C and MX40C)
Parameter Min Typical Max Unit
Wavelength Range 1527.6 - 1565.5 nm
Frequency Range 191.50 - 196.25 THz
Optical Output Power 12.5 13.5 14.5 dBm
Frequency Accuracy -1.5 - 1.5 GHz
Tuning Resolution - 50 - GHz
Fine Tuning Resolution 1 MHz
Tuning Speed
(Between Wavelengths)
- 10 - s
Fine Tuning Range -30 - 30 GHz
Side Mode Suppresion Ratio (SMSR) 40 55 - dB
Optical Signal Noise Ratio (OSNR) 40 60 - dB
Intrinsic Linewidth - 10 15 kHz
Relative Intensity Noise (RIN)a - - -145 dB/Hz
Back Reflection - - -14 dB
Polarization Extinction Ratio (PER) 18 - - dB
  • The noise in the optical power normalized to the average power level.
L-Band Tunable Laser Specifications (MX10C-LB and MX40C-LB)
Parameter Min Typical Max Unit
Wavelength Range 1570.0 - 1608.8 nm
Frequency Range 186.35 - 190.95 THz
Optical Output Power 12.5 13.5 14.5 dBm
Frequency Accuracy -1.5 - 1.5 GHz
Tuning Resolution - 50 - GHz
Fine Tuning Resolution 1 MHz
Tuning Speed
(Between Wavelengths)
- 10 - s
Fine Tuning Range -30 - 30 GHz
Side Mode Suppresion Ratio (SMSR) 40 55 - dB
Optical Signal Noise Ratio (OSNR) 40 60 - dB
Intrinsic Linewidth - 10 15 kHz
Relative Intensity Noise (RIN)a - - -145 dB/Hz
Back Reflection - - -14 dB
Polarization Extinction Ratio (PER) 18 - - dB
  • The noise in the optical power normalized to the average power level.
1310 nm Fixed-Wavelength Laser Specifications (MX10C-1310 and MX40C-1310)
Parameter Min Typical Max Unit
Wavelength - 1310 - nm
Optical Output Power 12.5 13.5 14.5 dBm
Side Mode Suppresion Ratio (SMSR) 35 - - dB
Intrinsic Linewidth - 2 3 MHz
Polarization Extinction Ratio (PER) - 20 - dB

Alternate Laser Option

850 nm Fixed-Wavelength Laser Specifications (Substitute Internal Laser Option)a
  • Contact Tech Support to request the substitution of an an 850 nm fixed-wavelength laser.

System Overview

These High-Speed Optical Transmitters are fully integrated and contain both the laser source and the lithium niobate (LiNbO3) phase modulator; the only required external input is the signal source to the Amplifier RF In port. Either the internal laser or an external laser source may be coupled to the Laser In port, which is shown in the bottom-left corner of the diagram below. This port uses polarization-maintaining (PM) PANDA fiber with light linearly polarized along the slow axis, as shown on the front panel of the instrument. Optical power is monitored in three places (Monitor 1, Monitor 2, and Monitor 3) for the purpose of enabling power control. These power values are also available at the I/O port. Monitor 1 is at the laser input, Monitor 2 is at the output of the modulator, and Monitor 3 is at the final optical output.

Optical Transmitter Block Diagram
A Block Diagram of the Internal Setup of the High-Speed Optical Transmitters

Instrument Control

The graphical user interface (GUI) gives the user complete control over all instrument functionality. It is a resistive touchscreen display sensitive to both finger pressure and taps from a plastic stylus. The knob on the front panel of the housing can be used in place of the on-screen arrow buttons for quickly changing set-point values. Pressing (clicking) the knob will confirm a new set-point value. Additionally, the instruments can be driven using serial commands delivered via connectors on the rear panel.

Optical Transmitter Main Menu
Click to Enlarge

Figure 1: Home Screen of the MX10C Series 
(Identical to the MX40C Series)

The home screen of the MX10C series is shown in Figures 1. It is organized into three main sections.  

  • Left Column:
    • Buttons show the on/off status of the different instrument functions.
    • Tap a button to toggle the function on/off.
  • Middle Column:
    • Current operating parameters of each control function are shown.
    • Tap in this column to access the Settings page for each function.
  • Right Column:
    • Buttons provide access to various utility and help functions.
    • Tap to review and customize system settings.

The green dot that appears in the upper-right of the center column panels indicates that those functions are stable. The dot will blink if that function is still stabilizing. 

Functions and controls enabled by the GUI are further discussed in the following sections.

Laser and System Wavelength Settings

Optical Transmitter System Wavelength Settings Screen
Click to Enlarge

Figure 3: System Wavelength Selection Screen
Optical Transmitter Laser Settings Screen
Click to Enlarge

Figure 2: Laser Settings Screen

The laser setting screen shown in Figure 2 is accessed directly from the home screen. Each instrument includes a C- or L-band telecom-style laser that is tunable on the ITU 50 GHz grid or a 1310 nm fixed-wavelength laser. An 850 nm fixed-wavelength laser can be substituted by contacting techsupport@thorlabs.com. C-band and L-band lasers also support a fine tuning frequency offset feature, allowing the frequency to be adjusted by an offset from -30.000 GHz to +30.000 GHz in increments of 1 MHz. ITU Channel wavelengths are indexed for convenience; use the arrow buttons to step through the indices to select the desired wavelength.

This screen also allows the user to control whether or not the dither feature (available for tunable C- and L-band lasers only) is used to stabilize the wavelength. Turning dither off results in lower phase and intensity noise (see the Specs tab for a representative plot), but doing so may also result in the wavelength drifting slightly over time. If an external laser is used, the internal laser can be turned off by tapping the laser button on the home screen.

If an external laser is used, it may be necessary to change the power monitor calibration settings. These instruments can be used at wavelengths anywhere between 1250 nm and 1610 nm, and calibration settings are supplied for three wavelengths: 1310 nm, 1550 nm, and 1590 nm. These wavelengths represent the centers of the O-Band, C-Band, and L-Band. The default calibration setting corresponds to the wavelength range of the internal laser. If operating outside that wavelength range, change the power monitor calibration settings by tapping the Menu button on the home page. Select the System Wavelength setting, shown in Figure 4, to change the power monitor calibration wavelength to the value closest to the wavelength of the laser source being used.

Optical Transmitter Digital Amplifier Voltage In vs. Voltage Out
Click to Enlarge

Figure 5: Limiting amplifiers in the MX10C and MX40C transmitter series provide high gain and a user-adjustable output swing in 0.1 V increments.
Optical Transmitter Digital Amplifier Settings Screen
Click to Enlarge

Figure 4: Digital RF Amplifier Settings Screen for the MX10C and MX40C Series of Transmitters

Limiting RF Amplifier

The amplifiers used in the MX10C and MX40C series have “limiting” characteristics once a certain output voltage swing has been reached. This enables cleaner transmission of two-level digital signals. In addition, the peak-peak output swing can be adjusted to control the extinction ratio (ER) of the output optical signal. These controls can be accessed from the Amplifier Settings page shown in Figure 4. The relationship between the input and output signals is shown in Figure 5. Small signals experience high gain, but as the signal level increases, the output signal swing is limited at the chosen set point.

For small input signals (before the amplifier limits), these instruments can actually be operated in analog mode. In this mode, the Output Swing is automatically set to its maximum value so that the linear gain region is maximized. Note that this only works if the input signal swing is kept small enough not to saturate the amplifier. See the manual for details.

The eye crossing point can be also adjusted during both digital and analog mode operation. A set point of 0 specifies a 50% crossing, which corresponds to the point midway between the signal's maximum and minimum values. Set points of -100 and +100 specify 35% and 65% crossings, respectively.

Variable Optical Attenuator

Optical Transmitter Variable Optical Attenuator Settings Screen
Click to Enlarge

Figure 6: VOA Settings Screen

The VOA provides the means for adjusting and stabilizing the modulated optical output power. The VOA settings screen, which is shown in Figure 6, allows the user to choose between and adjust the parameters of the two operational modes. In Constant Attenuation mode, the attenuation level between the Return from Modulator input port and the Final Optical Output port is fixed, which allows power fluctuations at the input of the power controller to be transferred to the output. In Constant Output Power Mode, the final optical output power is held constant independent of the input fluctuations. In this mode, the VOA is effectively used as a power stabilizer. Tap the Step function button at the right of the screen to change the step size by which the arrows increment or decrement the set point values.

The VOA settings screen also allows the user to select the units used to report the power readings and parameters on all pages. Use the Power Units field to choose whether power values are reported as mW or dBm.

Rear Panel

The rear panel provides additional safety and utility functions such as the laser safety interlock and the power monitor output, RS-232, and USB ports. The USB interface is currently used only for firmware upgrades that are made available on Thorlabs website. Future revisions of the firmware will provide for remote control of the instrument's functions.

All units are shipped from Thorlabs with a shorting device that is already installed in the interlock connector, thus allowing the instrument to be operated normally right out of the box. To make use of the interlock feature, a 2.5 mm plug can be wired to the remote interlock switch and plugged into the back-panel interlock jack in place of the shorting plug. Electrical specifications for this function are provided in the manuals, which can be accessed by clicking on the red document icons () below.

Front Panels

MX10C Optical Transmitter Front Panel
Click to Enlarge

MX10C Optical Transmitter Series Front Panel
MX40C Optical Transmitter Front Panel
Click to Enlarge

MX40C Optical Transmitter Series Front Panel
Callout Description
1 Touchscreen Display and Control
2 Value Adjustment Knob
3 Key Switch and Indicator Light for Internal Laser
4 Earth Ground Port for ESD Wrist Strap Banana Plug
5a Laser Out for Internal Laser Source,
Accepts PM Fiber with FC/PC Connector
6a Laser In to Modulator,
Accepts PM Fiber with FC/PC Connector
7b Optical Out: Final Output from Modulator
8 Amplifier Out: Signal from Internal Amplifier, SMA Female
9 Modulator RF In: Signal to Modulator, SMA Female
10 Amplifier RF In: Signal Input to Amplifier, SMA Female
11 On/Standby Button
  • Uses PM PANDA Fiber for Internal Connection
  • Uses SMF-28-Compatible Fiber for Internal Connection
Callout Description
1 Touchscreen Display and Control
2 Value Adjustment Knob
3 Key Switch and Indicator Light for Internal Laser
4 Earth Ground Port for ESD Wrist Strap Banana Plug
5a Laser Out for Internal Laser Source,
Accepts PM Fiber with FC/PC Connector
6a Laser In to Modulator,
Accepts PM Fiber with FC/PC Connector
7b Optical Out: Final Output from Modulator
8 Amplifier RF In: Signal Input to Amplifier, K™ Female
9 On/Standby Button
  • Uses PM PANDA Fiber for Internal Connection
  • Uses SMF-28-Compatible Fiber for Internal Connection

Back Panel

MX10C MX40C Optical Transmitter Back Panel
Click to Enlarge

The back panel format is the same for each of the high-speed optical transmitters.
Callout Description
1a I/O Control Port
Outputs from Three Integrated Power Monitors
2 Laser Interlock Jack
3a RS-232 Control Port
4 USB Port (Type B)
5 AC Power Cord Connector
6 Fuse Tray
7 AC Power Switch
  • See the Pin Diagrams tab for pin assignments.

 I/O DB15 Connector

I/O DB15 Connector
The I/O connector provides analog outputs from the three power monitors.
Pin Description Pin Description
1 Power Monitor 1 9 Analog Ground
2 Power Monitor 2 10 Analog Ground
3 Power Monitor 3 11 Reserved for Future Use
4 Reserved for Future Use 12 Reserved for Future Use
5 Analog Ground 13 Monitor 1 Gain Indicator
6 Analog Ground 14 Monitor 2 Gain Indicator
7 Analog Ground 15 Monitor 3 Gain Indicator
8 Analog Ground - -

RS-232 Connector

RS-232 Connector
The RS-232 connector is included to support remote operation.
Pin Description
1 Not Connected
2 RS232 Input
3 RS232 Output
4 Not Connected
5 Digital Ground
6 Not Connected
7 Not Connected
8 Not Connected
9 Not Connected

USB Type B Connector

USB Type B Connector
The USB connector is provided for firmware upgrades and future remote operation.

Each High-Speed Optical Transmitter Includes:

  • Optical Transmitter Main Unit
  • Power Cord According to Local Supply (Determined by Ordering Location)
  • PM Loop-Back Fiber Optic Cable
  • SMA Loop-Back RF Cable (MX10C Series Only)
  • Interlock Keys for Front Panel
  • 2.5 mm Interlock Pin (Pre-installed in Back Panel)
  • 1.25 A, 250 VAC Fuse
  • USB Type A to Type B Cable, 6' Long
Screen Capture of the Remote Control Tool Software
Click to Enlarge

The GUI of the Remote Control Software Tool

Software for the MX10C and MX40C Series of Optical Transmitters

Control the Optical Transmitters Remotely via Serial Commands
Serial commands sent to the MX10C or MX40C series of optical transmitters can control the functionality of the internal laser, digital RF amplifier, and variable optical attenuator (VOA), as well as general system parameter settings. The commands can be sent from a computer running any operating system to the RS-232 port on the back panel of the optical transmitter. Computers running Windows® 7, or later versions of the operating system, can send serial commands to the USB port on the back panel of the MX10C or MX40C transmitter series. The touchscreen interface remains active while the optical transmitter is controlled remotely. Descriptions of how to connect a controlling computer to the optical transmitter, the serial command set, and descriptions of each command are included in the Remote Control User Guide.

Application Demonstrating GUI-Based Remote Control of the Optical Transmitters
The Remote Control Software Tool, which is available for download, is an example graphical user interface (GUI) provided for testing, demonstrating, and exploring the use of the different serial commands. This program is not required to operate the optical transmitter remotely. It opens a connection to the laser source and sends commands in response to buttons clicked by users. Commands sent to the optical transmitter, responses from it, and status information messages are logged to the three rectangular fields located beneath the buttons. Please see the Remote Control User Guide for more information. This program can be used as a basis for the development of custom applications. Please contact us to request the source code.


Version 1.8.7 (May 5, 2022)

Click on the link below to download the Remote Control Software Tool.

Software Download

Firmware Update

Version 1.8.3 (January 13, 2020)

Click on the link below to download the latest firmware.

Firmware Download

Laser Safety and Classification

Safe practices and proper usage of safety equipment should be taken into consideration when operating lasers. The eye is susceptible to injury, even from very low levels of laser light. Thorlabs offers a range of laser safety accessories that can be used to reduce the risk of accidents or injuries. Laser emission in the visible and near infrared spectral ranges has the greatest potential for retinal injury, as the cornea and lens are transparent to those wavelengths, and the lens can focus the laser energy onto the retina. 

Laser Glasses Laser Curtains Blackout Materials
Enclosure Systems Laser Viewing Cards Alignment Tools
Shutter and Controllers Laser Safety Signs

Safe Practices and Light Safety Accessories

  • Laser safety eyewear must be worn whenever working with Class 3 or 4 lasers.
  • Regardless of laser class, Thorlabs recommends the use of laser safety eyewear whenever working with laser beams with non-negligible powers, since metallic tools such as screwdrivers can accidentally redirect a beam.
  • Laser goggles designed for specific wavelengths should be clearly available near laser setups to protect the wearer from unintentional laser reflections.
  • Goggles are marked with the wavelength range over which protection is afforded and the minimum optical density within that range.
  • Laser Safety Curtains and Laser Safety Fabric shield other parts of the lab from high energy lasers.
  • Blackout Materials can prevent direct or reflected light from leaving the experimental setup area.
  • Thorlabs' Enclosure Systems can be used to contain optical setups to isolate or minimize laser hazards.
  • A fiber-pigtailed laser should always be turned off before connecting it to or disconnecting it from another fiber, especially when the laser is at power levels above 10 mW.
  • All beams should be terminated at the edge of the table, and laboratory doors should be closed whenever a laser is in use.
  • Do not place laser beams at eye level.
  • Carry out experiments on an optical table such that all laser beams travel horizontally.
  • Remove unnecessary reflective items such as reflective jewelry (e.g., rings, watches, etc.) while working near the beam path.
  • Be aware that lenses and other optical devices may reflect a portion of the incident beam from the front or rear surface.
  • Operate a laser at the minimum power necessary for any operation.
  • If possible, reduce the output power of a laser during alignment procedures.
  • Use beam shutters and filters to reduce the beam power.
  • Post appropriate warning signs or labels near laser setups or rooms.
  • Use a laser sign with a lightbox if operating Class 3R or 4 lasers (i.e., lasers requiring the use of a safety interlock).
  • Do not use Laser Viewing Cards in place of a proper Beam Trap.


Laser Classification

Lasers are categorized into different classes according to their ability to cause eye and other damage. The International Electrotechnical Commission (IEC) is a global organization that prepares and publishes international standards for all electrical, electronic, and related technologies. The IEC document 60825-1 outlines the safety of laser products. A description of each class of laser is given below:

Class Description Warning Label
1 This class of laser is safe under all conditions of normal use, including use with optical instruments for intrabeam viewing. Lasers in this class do not emit radiation at levels that may cause injury during normal operation, and therefore the maximum permissible exposure (MPE) cannot be exceeded. Class 1 lasers can also include enclosed, high-power lasers where exposure to the radiation is not possible without opening or shutting down the laser.  Class 1
1M Class 1M lasers are safe except when used in conjunction with optical components such as telescopes and microscopes. Lasers belonging to this class emit large-diameter or divergent beams, and the MPE cannot normally be exceeded unless focusing or imaging optics are used to narrow the beam. However, if the beam is refocused, the hazard may be increased and the class may be changed accordingly.  Class 1M
2 Class 2 lasers, which are limited to 1 mW of visible continuous-wave radiation, are safe because the blink reflex will limit the exposure in the eye to 0.25 seconds. This category only applies to visible radiation (400 - 700 nm).  Class 2
2M Because of the blink reflex, this class of laser is classified as safe as long as the beam is not viewed through optical instruments. This laser class also applies to larger-diameter or diverging laser beams.  Class 2M
3R Class 3R lasers produce visible and invisible light that is hazardous under direct and specular-reflection viewing conditions. Eye injuries may occur if you directly view the beam, especially when using optical instruments. Lasers in this class are considered safe as long as they are handled with restricted beam viewing. The MPE can be exceeded with this class of laser; however, this presents a low risk level to injury. Visible, continuous-wave lasers in this class are limited to 5 mW of output power.  Class 3R
3B Class 3B lasers are hazardous to the eye if exposed directly. Diffuse reflections are usually not harmful, but may be when using higher-power Class 3B lasers. Safe handling of devices in this class includes wearing protective eyewear where direct viewing of the laser beam may occur. Lasers of this class must be equipped with a key switch and a safety interlock; moreover, laser safety signs should be used, such that the laser cannot be used without the safety light turning on. Laser products with power output near the upper range of Class 3B may also cause skin burns.  Class 3B
4 This class of laser may cause damage to the skin, and also to the eye, even from the viewing of diffuse reflections. These hazards may also apply to indirect or non-specular reflections of the beam, even from apparently matte surfaces. Great care must be taken when handling these lasers. They also represent a fire risk, because they may ignite combustible material. Class 4 lasers must be equipped with a key switch and a safety interlock.  Class 4
All class 2 lasers (and higher) must display, in addition to the corresponding sign above, this triangular warning sign.  Warning Symbol

Janis Valdmanis, Ph.D. Optics
Ultrafast Optoelectronics
General Manager

Custom and OEM Options

When your application requirements are not met by our range of catalog products or their variety of user-configurable features, please contact me to discuss how we may serve your custom or OEM needs.  

Request a Demo Unit

Explore the benefits of using a Thorlabs high-speed instrument in your setup and under your test conditions with a demo unit. Contact me for details.

Contact Me

MX40B with cover removed
Click to Enlarge

The MX40B Digital Reference Transmitter

Design, Manufacturing, and Testing Capabilities

Thorlabs' Ultrafast Optoelectronics Team designs, develops, and manufactures high-speed components and instrumentation for a variety of photonics applications having frequency responses up to 110 GHz. Our extensive experience in high-speed photonics is supported by core expertise in RF/microwave design, optics, fiber optics, optomechanical design, and mixed-signal electronics. As a division of Thorlabs, a company with deep vertical integration and a portfolio of over 20,000 products, we are able to provide and support a wide selection of equipment and continually expand our offerings.

Our catalog and custom products include a range of integrated fiber-optic transmitters, modulator drivers and controllers, detectors, receivers, pulsed lasers, variable optical attenuators, and a variety of accessories. Beyond these products, we welcome opportunities to design and produce custom and OEM products that fall within our range of capabilities and expertise. Some of our key capabilities are:

  • Detector and Receiver Design, to 70 GHz
  • Fiber-Optic Transmitter Design, to 110 GHz
  • RF & Microwave Design and Simulation
  • Design of Fiber-Optic and Photonics Sub-Assemblies
  • High-Speed Testing, to 110 GHz
  • Micro-Assembly and Wire Bonding
  • Hermetic Sealing of Microwave Modules
  • Fiber Splicing of Assemblies
  • Custom Laser Engraving
  • Qualification Testing

Overview of Custom and Catalog Products

Our catalog product line includes a range of integrated fiber-optic transmitters, modulator drivers and controllers, detectors, pulsed lasers, and accessories. In addition to these, we offer related items, such as receivers and customized catalog products. The following sections give an overview of our spectrum of custom and catalog products, from fully integrated instruments to component-level modules.

Fiber-Optic Instruments

To meet a range of requirements, our fiber-optic instruments span a variety integration levels. Each complete transmitter includes a tunable laser, a modulator with driver amplifier and bias controller, full control of optical output power, and an intuitive touchscreen interface. The tunable lasers, modulator drivers, and modulator bias controllers are also available separately. These instruments have full remote control capability and can be addressed using serial commands sent from a PC.

  • Fiber-Optic Transmitters, to 110 GHz
  • Linear and Digital Transmitters
  • Electrical-to-Optical Converters, to 110 GHz
  • Modulator Drivers
  • Modulator Bias Controllers
  • C- and L-Band Tunable Lasers

Customization options include internal laser sources, operating wavelength ranges, optical fiber types, and amplifier types.

Fiber-Optic Components

Our component-level, custom and catalog fiber-optic products take advantage of our module design and hermetic sealing capability. Products include detectors with frequency responses up to 50 GHz, and we also specialize in developing fiber-optic receivers, operating up to and beyond 40 GHz, for instrumentation markets. Closely related products include our amplifier modules, which we offer upon request, variable optical attenuators, microwave cables, and cable accessories.

  • Hermetically-Sealed Detectors, to 50 GHz
  • Fiber-Optic Receivers, to 40 GHz
  • Amplifier Modules
  • Electronic Variable Optical Attenuators
  • Microwave Cables and Accessories

Customization options include single mode and multimode optical fiber options, where applicable, and detectors optimized for time or frequency domain operation.

Free-Space Instruments

Our free-space instruments include detectors with frequency responses around 1 GHz and pulsed lasers. Our pulsed lasers generate variable-width, nanosecond-duration pulses, and a range of models with different wavelengths and optical output powers are offered. User-adjustable repetition rates and trigger in/out signals provide additional flexibility, and electronic delay-line products enable experimental synchronization of multiple lasers. We can also adapt our pulsed laser catalog offerings to provide gain-switching capability for the generation of pulses in the 100 ps range.

  • Pulsed Lasers with Fixed 10 ns Pulse Duration
  • Pulsed Lasers with Variable Pulse Width and Repetition Rates
  • Electronic Delay Units to Synchronize NPL Series Pulsed Lasers
  • Amplified Detectors

Customization options for the pulsed lasers include emission wavelength, optical output powers, and sub-nanosecond pulse widths.

Choose Optical Transmitter by Application

  1. Beginning at the left side of the table, choose your desired system characteristics.
  2. Follow the table to the right and continue to select characteristics from the options within the same row as your previous selection.
  3. After reaching a Base Item #, choose a laser type. Your system's item # will be your base item # combined with the suffix for your laser type, e.g. MX40B-1310.
Start Here Follow the Table to the Right and Choose From These Options Find Your System Here
Modulator Type Primary Application Modulation Format Speed RF Input Base Item # Item # Suffix:
Laser Type
Amplitude Time Domain / Eye Diagram Linear / 4-Level PAM4 32 GBaud Differential MX35D No Suffix:
C-Band Tunable Laser

L-Band Tunable Laser

1310 nm Fixed Laser

850 nm Fixed Lasera,b
Single Ended MX35E
56 GBaud MX65E
Digital / 2-Level NRZ / OOK 10 Gbps MX10B
40 Gbps MX40B
56 Gbps MX50E
56 Gbps MX65E
Frequency Domain / VNA 40 GHz MX40G
70 GHz MX70G
110 GHz MX110G
Phase 10 Gbps MX10C
40 Gbps MX40C
  • The 850 nm fixed laser is not available for the following base item #s:
    • MX10C
    • MX40C
    • MX65E
    • MX70G
    • MX110G
  • The MX40G-850 transmitter is available through the website. For other systems with an 850 nm fixed laser, excluding those listed in footnote a, please contact Tech Support.

Choose Optical Transmitter Instrument by Features

Transmitter Instruments and Tunable Lasers
Item # Speed Internal Laser Internal Modulator
RF Amplifier
Variable Optical
Attenuator (VOA)
Automatic Bias Controller
(770 - 980 nm)
N/A - - - yes yes
(1250 - 1610 nm)
N/A - - - yes yes
Tunable Telecom-Grade Laser Sources
TLX1 N/A C-Band, Tunable - - - yes
TLX2 N/A L-Band, Tunable
High-Speed Modulator Drivers
(1250 - 1610 nm)
12.5 Gb/sa - - Digital yes yes
(1250 - 1610 nm)
40 Gb/sa
High-Speed Optical Transmitters
MX10B 12.5 Gb/sa C-Band, Tunable Intensity Digital yes yes
MX10B-LB 12.5 Gb/sa L-Band, Tunable
MX10B-1310 12.5 Gb/sa 1310 nm, Fixed
MX10C 12.5 Gb/sa C-Band, Tunable Phase Digital - yes
MX10C-LB 12.5 Gb/sa L-Band, Tunable
MX10C-1310 12.5 Gb/sa 1310 nm, Fixed
MX35E 35 GHzb C-Band, Tunable Intensity Linear yes yes
MX35E-LB 35 GHzb L-Band, Tunable
MX35E-1310 35 GHzb 1310 nm, Fixed
MX35D 35 GHzb C-Band, Tunable Intensity Linear with
yes yes
MX35D-LB 35 GHzb L-Band, Tunable
MX35D-1310 35 GHzb 1310 nm, Fixed
MX40B 40 Gb/sa C-Band, Tunable Intensity Digital yes yes info
MX40B-LB 40 Gb/sa L-Band, Tunable
MX40B-1310 40 Gb/sa 1310 nm, Fixed
MX40C 40 Gb/sa C-Band, Tunable Phase Digital - yes
MX40C-LB 40 Gb/sa L-Band, Tunable
MX40C-1310 40 Gb/sa 1310 nm, Fixed
MX50E-850 50 GHzb 852 nm, Fixed Intensity Linear yes yes
MX65E 65 GHzb C-Band, Tunable Intensity Linear yes yes
MX65E-LB 65 GHzb L-Band, Tunable
MX65E-1310 65 GHzb 1310 nm, Fixed
E-O Converters for VNA Applications
MX40G 40 GHzb C-Band, Tunable Intensity - yes yes
MX40G-LB 40 GHzb L-Band, Tunable
MX40G-850 40 GHzb 850 nm, Fixed
MX40G-1310 40 GHzb 1310 nm, Fixed
MX70G 70 GHzb C-Band, Tunable Intensity - yes yes
MX70G-LB 70 GHzb L-Band, Tunable
MX70G-1310 70 GHzb 1310 nm, Fixed
MX70G-DB1 70 GHzb C-Band, Tunable Intensity - yes yes
1310 nm, Fixed
MX110G 110 GHzb C-Band, Tunable Intensity - yes yes
MX110G-1310 110 GHzb 1310 nm, Fixed
  • Maximum Supported Digital Bit Rate
  • Maximum Analog Bandwidth

The capabilities of Thorlabs' extensive range of transmitter instruments are summarized in the text and table below. All members of this product series share a similar interface, as well as a common remote control command set.

Automatic Bias Controller
Thorlabs' fully-featured automatic bias controller provides complete and precise control of DC bias and optical output power for any fiber-coupled LiNbO3 EO intensity modulator, regardless of signal speed. Automatic bias controllers are ideal for use within a customized setup that uses an external laser, intensity modulator, signal source, and RF amplifier.

Tunable Telecom-Grade Laser Sources
Emitting in the C-band or the L-band, these lasers have narrow typical linewidths of 10 kHz. A frequency dither option aids in stabilizing the laser wavelength, and the integrated variable optical attenuator (VOA) provides optical output power control. These lasers are tunable in 50 GHz steps across the ITU frequency grid, and feature a 1 MHz step size fine-tune capability, as well.

High-Speed Modulator Drivers
With an operational wavelength range of 1250 nm to 1610 nm, each modulator driver provides control for an external fiber-coupled LiNbO3 EO modulator. Each modulator driver includes an RF amplifier with amplitude and eye-crossing controls and accepts an external drive signal source. Models with integrated automatic bias controllers are offered for use with intensity EO modulators.

High-Speed Optical Transmitters
Designed to provide fully-integrated solutions for high-speed light modulation, these systems are built around a LiNbO3 intensity or phase modulator. The MX10B, MX40B, MX10C, and MX40C series of systems include a digital (limiting) RF amplifier, which offers fixed gain and an adjustable output voltage swing. The MX35E, MX50E, and MX65E series include a high-bandwidth linear (analog) RF amplifier, making it well suited for pulse amplitude modulation and related applications.

E-O Converters for VNA Applications
With our MX40G, MX70G, and MX110G series of E-O converters, any E-E vector network analyzer can be used to perform optical testing up to 40 GHz, 70 GHz, and 110 GHz respectively. The E-O converter is a fully-integrated solution that includes a laser, a modulator, and bias control.

Posted Comments:
mitch  (posted 2017-01-25 05:10:19.753)
Hi, I would like to use the MX10B or C for RF-over optical. Would the MX10B be suitable for a 2.4GHz RF carrier (say WiFi)? Thanks
tfrisch  (posted 2017-01-26 05:15:25.0)
Hello, thank you for contacting Thorlabs. MX10B or MX10C should be suitable at 2.4GHz, and I will reach out to you directly to discuss your application.
paulg  (posted 2016-09-26 13:45:43.643)
Hi, Can you make the MX40B @ 850 nm ?
jlow  (posted 2016-09-27 02:41:56.0)
Response from Jeremy at Thorlabs: We will contact you directly to discuss about the 850nm modulator.
eaosec  (posted 2016-08-10 02:41:07.97)
Hi, We are interested in an analog version of the MX40 transmitter S Yu Advanced Electro-Optics Co Taiwan
Back to Top

High-Speed Optical Transmitters with Phase Modulators

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
MX10C Support Documentation
MX10CHigh-Speed Optical Transmitter, C-Band Laser, Phase Modulator, 12.5 Gb/s Max
Lead Time
MX10C-LB Support Documentation
MX10C-LBHigh-Speed Optical Transmitter, L-Band Laser, Phase Modulator, 12.5 Gb/s Max
Lead Time
MX10C-1310 Support Documentation
MX10C-1310High-Speed Optical Transmitter, 1310 nm Laser, Phase Modulator, 12.5 Gb/s Max
Lead Time
MX40C Support Documentation
MX40CHigh-Speed Optical Transmitter, C-Band Laser, Phase Modulator, 40 Gb/s Max
Lead Time
MX40C-LB Support Documentation
MX40C-LBHigh-Speed Optical Transmitter, L-Band Laser, Phase Modulator, 40 Gb/s Max
Lead Time
MX40C-1310 Support Documentation
MX40C-1310High-Speed Optical Transmitter, 1310 nm Laser, Phase Modulator, 40 Gb/s Max
Lead Time