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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 C-Band Tunable Laser and Automatic Power Control
  • Accepts External Lasers from 1250 to 1610 nm


Optical Transmitter with
12.5 Gb/s Phase Modulator

Touch-Panel Interface for Device Control

Related Items

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Optical Transmitter Block Diagram
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Block diagram showing the internal setup of the high-speed optical transmitters. Thorlabs also offers Reference Transmitters based on intensity modulators.

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

We Design, Develop, and Manufacture
Equipment up to 70 GHz


Demo Unit Requests?

Product Suggestions?

Custom or OEM Applications?

Contact Me


  • 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 for Applications up to 12.5 Gb/s
    • MX40C for Applications up to 40 Gb/s
    • User-Adjustable RF Amplifier Output Swing
  • Integrated C-Band Laser Tunable on ITU 50 GHz
  • Substitution for Integrated Laser Available by Contacting Tech Support:
    • L-Band Laser Tunable on ITU 50 GHz
    • 850 nm Fixed-Wavelength Laser
    • 1310 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 are both designed for digital applications, and the maximum voltage output swing of their limiting RF amplifiers is user-adjustable. Each optical transmitter has a built-in telecom-grade tunable 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. Both optical transmitters are well suited to phase-shift keying binary modulation formats including BPSK and DPSK. 

The internal C-band laser is tunable over a range of 1527.6 nm - 1565.5 nm (191.50 THz - 196.25 THz) on the ITU 50 GHz grid. A dither feature is available to stabilize the wavelength (see the Operation tab for more information). Instruments with an integrated L-band tunable laser, an 850 nm fixed-wavelength laser, or a 1310 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 PM 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.

The MX10C 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 Panel tab for details). The RF port on the MX10C accepts SMA connectors, and the RF port on the MX40C 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 graphical user interface (GUI) and user-customizable features, and we provide a remote control user guide and a remote control software tool (see the Software tab) for download.

K™ is a trademark of Anritsu.

General System Specifications
Item # MX10C MX40C
Amplifier Type Digital (Limiting)
Bit Rate (Maximum) 12.5 Gb/s 40 Gb/s
Internal Laser Wavelength Rangea 1527.6 -1565.5 nm (C-Band)
Output Power (Maximum) 13.5 dBm (Typical)
External Laserb Wavelength Range 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 Lossc -10 dB (Any RF Port, Typical)
Modulator Type Phase
Optical Insertion Loss (Typical)d 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-Style Fiber
SM Port: SMF-28-Compatible Fiber
Fiber Connectors FC/PC, 2.0 mm Narrow Key
  • Tunable in 50 GHz steps. An L-Band tunable laser or a 1310 nm fixed-wavelength laser can be substituted for the standard C-Band tunable laser upon request: contact Thorlabs’ Tech Support.
  • User-Supplied
  • To the -3 dB Bandwidth
  • Laser IN to Optical OUT. Insertion Loss at 1310 nm is typically 2 dB higher than at 1550 nm.
Digital (Limiting) RF Amplifier Specifications
Item # 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 (User-Adjustable)a 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 and ±10 V for the MX40C.
  • Large Signal, Digital Response
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
Output Optical Power 12.5 13.5 14.5 dBm
Frequency Accuracy -1.5 - 1.5 GHz
Tuning Resolution - 50 - GHz
Tuning Speed
(Between Wavelengths)
- 10 - s
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.

Substitute Laser Options

Contact Tech Support to request the substitution of an L-band tunable or an 850 nm or 1310 nm fixed-wavelength laser in place of the
C-band tunable laser. Click More [+] on the expandable tables below to view specifications for these alternate lasers.

L-Band Tunable Laser Specifications (Substitute Internal Laser Option)a
850 nm Fixed-Wavelength Laser Specifications (Substitute Internal Laser Option)a
1310 nm Fixed-Wavelength Laser Specifications (Substitute Internal Laser Option)a
  • Contact Tech Support to request the substitution of an L-Band tunable laser or an 850 or 1310 nm fixed-wavelength
    laser for the standard C-Band tunable laser.
  • The noise in the optical power normalized to the average power level.

Phase Modulator Specifications
Item # 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 Lossd 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 MX10B and MX10C. 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 on the MX40B and MX40C.
  • Laser IN to Optical OUT. Insertion Loss at 1310 nm is typically 2 dB higher than at 1550 nm.
Power Monitor and VOAa Specifications (MX10C and MX40C)
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.
Power and Environmental Specifications (MX10C and MX40C)
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

System Overview

These High-Speed Optical Transmitters are fully integrated and contain both the laser source and the lithium niobate 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) 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 (Identical to the MX40C)

The Home Screen of the MX10C 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-band telecom-style laser that is tunable on the ITU 50 GHz grid. (An L-band telecom-style laser that is also tunable on the ITU 50 GHz grid, or an 850 nm or 1310 nm fixed-wavelength laser that are not, can be substituted for the C-band laser by contacting 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 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 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

Limiting RF Amplifier

The amplifiers used in the MX10C and MX40C 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 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
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MX10C Optical Transmitter Front Panel
MX40C Optical Transmitter Front Panel
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MX40C Optical Transmitter 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 future remote operation that will be enabled by future firmware upgrades.
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 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 TLX Laser Remote Control Tool Software V1.6
Click to Enlarge

The GUI of the Remote Control Software Tool 

Software for the MX10C and MX40C Optical Transmitters

Control the Optical Transmitters Remotely via Serial Commands
Serial commands sent to the MX10C or MX40C 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. 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 MX10C or MX40C 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 1.6.1 (September 26, 2017)

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

Software Download

Firmware Update

Version 1.6.2 (November 15, 2017)

Click on the link below to download the latest firmware.

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

Safe Practices and Light Safety Accessories

  • Thorlabs recommends the use of safety eyewear whenever working with laser beams with non-negligible powers (i.e., > Class 1) 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.
  • 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 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 are limited to 5 mW of output power in this class.  Class 3R
3B Class 3B lasers are hazardous to the eye if exposed directly. However, diffuse reflections are not harmful. Safe handling of devices in this class includes wearing protective eyewear where direct viewing of the laser beam may occur. In addition, laser safety signs lightboxes should be used with lasers that require a safety interlock so that the laser cannot be used without the safety light turning on. Class-3B lasers must be equipped with a key switch and a safety interlock.  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 70 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 70 GHz
  • RF & Microwave Design and Simulation
  • Design of Fiber-Optic and Photonics Sub-Assemblies
  • High-Speed Testing, to 70 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 of 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 70 GHz
  • Linear and Digital Transmitters
  • Electrical-to-Optical Converters, to 70 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.

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

Transmitters with Integrated Phase Modulators and Lasers

Selected Specificationsa
Item # MX10C MX40C
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
Wavelength Range 1527.6 - 1565.5 nm (C-Band)
Frequency Range 191.50 - 196.25 THz
Intrinsic Linewidth 10 kHz (Typical)
15 kHz (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.
  • Tunable in 50 GHz steps. An internal L-band tunable laser or an 850 nm or 1310 nm fixed-wavelength laser is available upon request. Please contact Tech Support for details.
  • User-provided.
  • High-Speed Phase Modulation
  • Digital Operation
    • MX10C: 12.5 Gb/s Maximum System Bit Rate
    • MX40C: 40 Gb/s Maximum System Bit Rate
  • Analog (Linear) Operation
    • MX10C: Up to 7 GHz Small Signal Bandwidth
    • MX40C: Up to 20 GHz Small Signal Bandwidth
  • LiNbO3 Phase Modulator Built Into the Package
  • Integrated C-Band* Laser is Tunable on ITU 50 GHz Grid

These all-in-one optical transmitters each integrate a high-speed phase modulator with a C-band* tunable laser source, RF driver amplifier, and variable optical attenuator. The MX10C phase modulator supports speeds of up to 12.5 Gb/s digital operation and up to 7 GHz when used in analog mode, while the MX40C 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.

*Custom configurations, including versions of these optical transmitters with an internal L-band tunable laser, an 850 nm fixed-wavelength laser, or a 1310 nm fixed-wavelength laser, are also available upon request. Specifications for all internal laser options are included in the Specs tab. Please contact Tech Support for more information.

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, Phase Modulator, 12.5 Gb/s Max
MX40C Support Documentation
MX40CHigh-Speed Optical Transmitter, Phase Modulator, 40 Gb/s Max
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