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Fiber-Optic, Calibrated Electrical-to-Optical Converters

  • Integrated Modulator with Bias Control
  • Frequency Response from DC to 40 GHz or 70 GHz
  • Optical Accessory for Electrical Vector Network Analyzer (VNA)
  • Tunable C-Band, Tunable L-Band, or 1310 nm Laser


Calibrated E-O Converter,
DC to 70 GHz
Integrated C-Band Laser

An E-O converter provides optical test capability for
an all-electrical vector network analyzer (VNA).

Related Items

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E-O Converter Block Diagram
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Block Diagram Showing the Internal Setup of the E-O Converters 

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

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


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  • Enables E-E Test Equipment to Characterize O-E Devices
  • Two Frequency Response Ranges Available:
    • DC to 40 GHz: MX40G Series
    • DC to 70 GHz: MX70GSeries
  • Multiple Laser Options
    • C-Band Laser Tunable on ITU 50 GHz Grid
    • L-Band Laser Tunable on ITU 50 GHz Grid
    • 1310 nm Fixed-Wavelength Laser
    • Contact Tech Support for an 850 nm Fixed-Wavelength Laser for the MX40G
  • Mach-Zehnder Intensity Modulator and Bias Controller with Manual and Fully Automatic Operation Modes
  • Variable Optical Attenuator (VOA) for Automatic or Manual Power Control
  • S21 De-Embedding Parameters Supplied (*.s2p File)
  • Operation from 1250 to 1610 nm with User-Supplied External Laser Source
  • Control via Intuitive Touchscreen Interface or Remotely Using USB or RS-232 Connections
  • Custom Configurations Available by Contacting the Ultrafast Optoelectronics Team

Thorlabs' Calibrated Electrical-to-Optical (E-O) Converters generate optical signals from electrical inputs. One of the primary applications of an E-O converter is enabling electrical-to-electrical (E-E) test equipment to characterize optical-to-electrical (O-E) devices. These calibrated E-O converters are particularly well suited for use as accessories providing optical test capability for an E-E VNA, as is illustrated at the top of this page. With each converter, Thorlabs provides a *.s2p file containing S21 magnitude and phase data for the modulator across its frequency range of operation. These data can be used for either simple magnitude correction of the response or for complete de-embedding of the O-E device under test's response from the full E-E test system response. Please see Thorlabs' application note on de-embedding procedures for a detailed explanation.

Each converter's telecom-grade components include a lithium niobate (LiNbO3) modulator stabilized by a fully automatic bias controller and a tunable or fixed-wavelength laser source. Variable optical attenuators (VOAs) and power monitors enable completely automated output power control and stabilization. The key elements of the converter are shown in the diagram to the right. The power monitors are calibrated at 1310 nm, 1550 nm, and 1590 nm, and provide the user with accurate power readings at or near those wavelengths.

The C-band laser of the MX40G and MX70G and the L-band laser of the MX40G-LB and MX70G-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 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 MX40G-1310 and MX70G-1310 has a typical wavelength of 1310 nm. An 850 nm fixed-wavelength laser is also available for the MX40G upon request (contact Tech Support).

An external laser source, operating from 1250 to 1610 nm, can also be used to provide the optical input. 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 Modulator RF In port of the MX40G series of converters accepts 2.92 mm (K™)† connectors, while the Modulator RF In port of the MX70G series of converters accepts 1.85 mm (V™)† connectors. Thorlabs' complete selection of compatible microwave cables and adapters can be viewed here.

These converters can be controlled in one of two ways. The simplest method is by 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, and we provide a remote control user guide and a remote control software tool (see the Software tab) for download.

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

K™ and V™ are trademarks of Anritsu.

Please note: Item #s ending in -LB or -1310 will ship from the US within 7 to 10 days of placing an order if all component parts are available.
General System Specifications
Item # MX40G MX40G-LB MX40G-1310 MX70G MX70G-LB MX70G-1310
Frequency Responsea
(Click for Plot)
DC - 40 GHz DC - 70 GHz
Uncertainty of Supplied
Magnitude Responsea
40 MHz to 40 GHz: ±0.85 dB 40 MHz to 40 GHz: ±0.85 dB
40 GHz to 70 GHz: ±1.75 dB
Input RF Connector Type 2.92 mm Connectorb 1.85 mm Connectorc
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 Ranged 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 Lasere Wavelength Rangef 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 Max)
Modulator Type Intensity
Modulator RF Inputg ±1 V (Max for Linear Response)h; ±5 V (Absolute Max)
Optical Insertion Loss (Typical)i 5.0 dB (1550 nm); 7.0 dB (1310 nm)
Absolute Stabilityj 0.1 dB (Dither Mode); 0.2 dB (Ratio Mode)
Relative Stabilityk 0.02 dB (Dither Mode); 0.02 dB (Ratio Mode)
Internal Optical Fiber PM Ports: PM PANDA Fiber
SM Port: SMF-28-Compatible Fiber
Fiber Connectors FC/PC, 2.0 mm Narrow Key
  • Measured frequency response (at each specified frequency) provided in *.s2p file on a USB drive with each unit.
  • The 2.92 mm connector can mate directly to an SMA, 3.5 mm, or K connector.
  • The 1.85 mm connector can mate directly to a 2.4 mm or V connector.
  • C- and L-band lasers are tunable in 50 GHz steps. An 850 nm fixed-wavelength laser can be substituted in the MX40G 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.
  • Peak to Peak
  • With Bias Point at Quadrature
  • Laser IN to Optical OUT.
  • Stability of modulation amplitude at any single frequency point, for 3 °C temperatue range and 4 hour time period.
  • Stability of modulation amplitude between frequency points (response shape), for 3 °C temperature range and 4 hour time period.
Intensity Modulator Specifications
Item # Prefix MX40G MX70G
Electro-optic Bandwidth (-3 dB) 40 GHz 70 GHz
DC Optical On/Off Extinction Ratio 20 dB
RF Drive Voltage (Vpi)a 5.5 VPP
Insertion Loss 4.0 dB (1550 nm)
6.0 dB (1310 nm)
  • At 1 GHz
Power Monitor and VOAa Specifications
Power Monitor Accuracyb ±0.5 dBm
Power Monitor Resolution 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
  • At Power Calibration Points: 1310 nm, 1550 nm, and 1590 nm
Power and Environmental Specifications
Main AC Voltage 100 VAC - 250 VAC
Power Consumption 60 VA
Line Frequency 50 Hz - 60 Hz
Operating Temperature 10 to 40 °C
Storage Temperature 0 to 50 °C
Relative Humiditya 5% to 85%
  • Non-Condensing Environment
C-Band Laser Frequency Noise Spectrum
Click to Enlarge

Frequency noise spectrum of the integrated C-band tunable laser. The dither function helps stabilize the wavelength. Turning the dither off provides for lower noise.
C-Band Tunable Laser Specifications (MX40G and MX70G)
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
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.
L-Band Tunable Laser Specifications (MX40G-LB and MX70G-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
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.
1310 nm Fixed-Wavelength Laser Specifications (MX40G-1310 and MX70G-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

Each calibrated E-O converter is fully integrated and contains a laser source and a lithium niobate (LiNbO3) Mach-Zehnder intensity modulator with automatic bias controller; the only required external input is the signal source to the Modulator RF In port. Either the internal laser or an external laser source may be coupled to the Laser In port, which can be seen 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 bias and power control. These power values are also available at the I/O port on the back panel of the instrument. 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.

MX40G E-O Converter Block Diagram
A Block Diagram of the Internal Setup of Thorlabs' Calibrated E-O Converters

De-Embedding Procedures

E-E System with MX40G and O-E DUT
Click to Enlarge

Figure 2: The  E-E system response measured by the E-E VNA is the combined response of the E-O converter and the O-E DUT. Blue indicates electrical connections and red is used for optical connections.
E-E System with O-E DUT Only
Click to Enlarge

Figure 1: The E-E system response measured by the E-E VNA is the response of the E-E DUT. Blue indicates electrical connections.

One of the primary applications of a calibrated electrical-to-optical (E-O) converter is enabling electrical-to-electrical (E-E) test equipment, like a vector network analyzer (VNA), to characterize optical-to-electrical (O-E) devices. E-E test equipment connects to and tests E-E systems as illustrated in Figure 1. As shown in Figure 2, the device is used to convert the electrical signal from Port 1 of the E-E VNA to an optical signal that is input into the O-E device under test (DUT), and the electrical signal resulting from the O-E DUT is then provided to Port 2 of the E-E test equipment. The response of the entire E-E system, which consists of the E-O converter and the O-E DUT together, is measured. Accurately recovering the response of the O-E DUT requires removing the response of the converter from the measured E-E system response. This is referred to as de-embedding.

Thorlabs provides a file (*.s2p format) with every calibrated E-O converter that contains the S21 magnitude and phase response of the modulator across its frequency range of operation. These data are used to perform the de-embedding process. Note that most modern E-E VNA systems provide a built-in function for doing this type of de-embedding based on the user-supplied *.s2p file. This is the easiest method. However, the de-embedding process can also be performed manually. These methods are described in detail in the application note.

Please click on the Specs tab to see typical frequency response plots for our converters.

Instrument Control

The graphical user interface (GUI) gives the user complete control over all instrument functionality. Each E-O converter uses 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 to quickly change setpoint values. Pressing (clicking) the knob will confirm a new setpoint value. Additionally, the instruments can be driven using serial commands delivered via connectors on the rear panel. This is described in the remote control user guide, and a Windows program that demonstrates remote control of the converter is available in the Software tab.

E-O Converter Main Menu
Click to Enlarge

Figure 3: Home Screen of the E-O Converter

The home screen of the converter, shown in Figure 3, is organized into three main sections. 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.  

  • 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.

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

Laser and System Wavelength Settings

E-O Converter System Wavelength Screen
Click to Enlarge

Figure 5: System Wavelength Selection Screen
E-O Converter Laser Settings Screen
Click to Enlarge

Figure 4: Laser Settings Screen

The laser setting screen shown in Figure 4 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 ITU Channel wavelengths are indexed for convenience; use the arrow buttons to step through the indices to select the desired wavelength. If finer control over emission wavelength is desired, tuning resolution to 1 MHz is available using remote serial control via USB or RS-232. 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 5, to change the power monitor calibration wavelength to the value closest to the wavelength of the laser source being used.

Modulator Bias Controller

E-O Converter LiNbO3 Intensity Modulator Bias Control
Click to Enlarge

Figure 7: Bias Settings Screen
E-O Converter LiNbO3 EO Modulator Bias Transmisstion Function
Click to Enlarge

Figure 6: Bias Points for an Intensity Modulator, in which Vpi is the Half-Wave Voltage

There are four bias control modes, which provide the option of operating with fully automatic bias control or under manual control. Three of the four automated operating modes, Peak, Quadrature, and Null, reference the regions labeled on the modulation transmission function, which is illustrated in Figure 6. When one of these modes is selected, a dither tone is used to hold the modulator at the respective bias point. The dither tone is part of a lock-in approach that maintains a stable bias point by compensating for modulator drift, which occurs over time due to the temperature sensitivity of the modulator. The dither tone can be set to a frequency between 1 and 10 kHz, and the amplitude of the tone can also be selected. Quadrature mode gives the option of operating on either the positive or negative slope of the function.

For those applications that require an automated, but ditherless, approach to maintaining a stable bias setpoint, select the Constant Ratio mode. It is enabled by tapping the MAN function on the right of the screen shown in Figure 7 and configuring the Ratio Setpoint and Slope values. This mode adjusts the bias voltage to maintain a chosen ratio between the intensity values reported by Monitor 1 and Monitor 2. The Slope setting allows the user to choose whether increasing voltage on the modulator increases or decreases the optical output power.

It can be useful to operate for brief periods of time at a bias fixed voltage and without a dither tone. A fixed bias voltage can be applied in one of two ways. When operating in Quadrature, Peak, or Null modes, tapping the value of Dither will toggle it between on and off states. When dither is toggled off, the value of the fixed bias voltage is held at the most recent automated bias voltage. This enables the user to make quick measurements, without the dither tone present, while the modulator is biased at one of the common modulator transmission function setpoints. The Constant Bias mode can also be accessed by tapping the Mode value and then the MAN function on the right of the screen. This page allows either the automated Constant Ratio or fixed-voltage Constant Bias modes to be enabled and configured.

Variable Optical Attenuator

E-O Converter Variable Optical Attenuator Settings Screen
Click to Enlarge

Figure 8: 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 8, 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 setpoint 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. Both the USB and RS-232 interfaces can be used for remote control operation of the E-O converter. The serial commands and control features available are fully described in the Remote Control User Guide. The USB interface is also used for installing firmware upgrades as they become available. Future revisions of the firmware will provide for additional remote control features and 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 manual

Front and Back Panels

MX40G E-O Converter Front Panel
Click to Enlarge

E-O Converter Front Panel
MX40G E-O Converter Back Panel
Click to Enlarge

E-O Converter Back Panel
Callout Description
1 Touchscreen Display and Control
2 Value Adjustment Knob
3 Key Switch and Status 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 FC/PC Connector
6a Laser In to Modulator,
Accepts PM Fiber FC/PC Connector
7b Optical Out: Final Output from Modulator
8 Modulator RF In: Signal to Modulator,
MX40G Series: 2.92 mm Femalec
MX70G Series: 1.85 mm Femaled
9 On/Standby Button
  • Uses PM PANDA Fiber for Internal Connection
  • Uses SMF-28-Compatible Fiber for Internal Connection
  • The 2.92 mm connector can mate directly to an SMA, 3.5 mm, or K connector.
  • The 1.85 mm connector can mate directly to a 2.4 mm or V connector.
Callout Description
1a I/O Control Port (DB15 Connector)
Outputs from Three Integrated Power Monitors
2 Laser Interlock Jack (2.5 mm Phono 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 supports remote operation.
Pin Description
1 Not Connected
2 RS-232 Input
3 RS-232 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 remote operation.

Each Electrical-to-Optical Converter Includes:

  • Calibrated E-O Converter Main Unit
  • Power Cord According to Local Supply (Determined by Ordering Location)
  • PM Loop-Back Fiber Optic Cable
  • 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
  • USB Storage Device with *.s2p File Characterizing Instrument
Screen Capture of the MX40G E-O Converter Remote Control Tool Software V1.5
Click to Enlarge

The GUI of the Remote Control Software Tool

Software for Thorlabs' Calibrated E-O Converters

Control the Converter Remotely via Serial Commands
Serial commands sent to the converter can control the functionality of the internal laser, bias controller for the built-in modulator, 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 device. 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 converter. The touchscreen interface remains active while the device is controlled remotely. Descriptions of how to connect a controlling computer to the converter, 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 Converter
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 converter remotely. It opens a connection to the device and sends commands in response buttons clicked by users. Commands sent to the converter, responses from the converter, and status informational 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 Laser Curtains 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.
  • 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 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.  

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 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.

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Transmitter Instruments and Tunable Lasers
Item # Speed Internal Laser Internal Modulator
RF Amplifier
Variable Optical
Attenuator (VOA)
Automatic Bias Controller
MBX 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
MX10A 12.5 Gb/sa - - Digital yes yes
MX40A 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
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
E-O Converters for VNA Applications
MX40G 40 GHzb C-Band, Tunable Intensity - yes yes
MX40G-LB 40 GHzb L-Band, Tunable
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
  • Maximum Supported Digital Bit Rate
  • Maximum Analog Bandwidth

Selection Guide for Transmitter Instruments

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 series includes a high-bandwidth linear (analog) RF amplifier with adjustable gain, making it well suited for pulse amplitude modulation and related applications.

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

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
MX40G Support Documentation
MX40GCalibrated Electrical-to-Optical Converter, C-Band Laser, 40 GHz
MX40G-LB Support Documentation
MX40G-LBCalibrated Electrical-to-Optical Converter, L-Band Laser, 40 GHz
Lead Time
MX40G-1310 Support Documentation
MX40G-1310Calibrated Electrical-to-Optical Converter, 1310 nm Laser, 40 GHz
Lead Time
MX70G Support Documentation
MX70GCalibrated Electrical-to-Optical Converter, C-Band Laser, 70 GHz
MX70G-LB Support Documentation
MX70G-LBCalibrated Electrical-to-Optical Converter, L-Band Laser, 70 GHz
Lead Time
MX70G-1310 Support Documentation
MX70G-1310Calibrated Electrical-to-Optical Converter, 1310 nm Laser, 70 GHz
Lead Time
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