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Benchtop High-Speed LiNbO3 Electro-Optic Modulator Drivers
Modulator Driver for Operation up to 12.5 Gb/s
Block Diagram of the Internal Setup of the MX10A and MX40A Modulator Drivers. See the Operation tab for details.
Janis Valdmanis, Ph.D. Optics
We Design, Develop, and Manufacture
|Power and Environmental Specifications|
|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|
|Optical Input Power||20 dBm (Maximum)
22 dBm (Absolute Max.)
|External Laser Wavelength Range||1250 - 1610 nm|
|Power Calibration Points||1310 nm, 1550 nm, and 1590 nm|
|Maximum Bit Rate (Digital Signal)||12.5 Gb/s||40 Gb/s|
|Small Signal Bandwidtha||7 GHz||20 GHz|
|Low Frequency Cutoff||100 kHz|
|Amplifier RF Input (Linear Response)b||100 mV (Maximum)||120 mV (Maximum)|
|Amplifier RF Input (Digital Mode)c||400 mV (Typical)
3.5 V (Maximum)
4 V (Absolute Max)
|400 mV (Typical)
4 V (Maximum)
6 V (Absolute Max)
|Maximum Amplifier DC Input||±15 V||±10 V|
|Maximum Bias Voltage to Modulator||±10 V (≥50 Ω Input Impedance)|
|Internal Fiber||PM Ports: PM PANDA-Style Fiber
SM Port: SMF-28-Compatible Fiber
|Fiber Connectors||FC/PC, 2.0 mm Narrow Key|
|Electrical Connectors||SMA Female|
|Rise/Fall Timed||35 ps||8 ps|
|RF Amplifier Gain||34 dB||30 dB|
|RF Amplifier Maximum Output Swing||3 V - 7 V (Adjustable)|
|Electrical Return Losse||-10 dB (Typical)|
|Power Monitor Accuracy||±0.5 dBm at Power Calibration Points|
|Power Monitor Resolution||0.01 dBm|
|Power Monitor Insertion Loss (Typical)||0.1 dB per Monitor|
|VOA Insertion Loss (Typical)||0.4 dB|
|VOA Attenuation||20 dB (Max)|
|VOA Response Time||1 s|
The block diagram below provides a basic illustration of the internal setup of the modulator drivers. The external laser is directed into the driver and through Monitor 1 before exiting to the external modulator. The output of the modulator then returns into the instrument and passes through the VOA-based power control system on its way to the output on the front panel. The drivers include a high-performance RF amplifier for driving the modulator. Automatic bias control is added for use with intensity modulators. The rear panel features output ports for several additional monitor and control functions.
These instruments can be fully controlled by using the resistive touchscreen display, which is sensitive to finger pressure or the tap of a plastic stylus. Additionally, 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.
The home screen is organized in three main sections.
The basic layout can be seen in the screenshots to the right. 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.
System Wavelength Setting
The System Wavelength may be selected on the Menu page, shown to the right. The choice of system wavelength specifies which calibration settings to apply to the intensity monitors in the modulator driver. The MX instruments can be used at wavelengths anywhere between 1250 nm and 1610 nm, but the power monitors are only calibrated at three main wavelengths: 1310 nm, 1550 nm, and 1590 nm. These wavelengths represent the centers of the O-Band, C-Band, and L-Band and therefore provide the user with accurate power readings at or near those wavelengths.
Each modulator driver includes a high-performance RF amplifier that provides a fixed gain to a user-supplied input signal. Users can select analog or digital operating mode for the amplifier. Analog operation allows for maximum linear modulation with low distortion. In digital mode, both the output swing and crossing point can be adjusted by the user while the gain is held constant. This adjustment allows the user to optimize the bit-error-rate (BER) performance by adjusting the amplifier’s internal threshold levels.
Bias Settings (For Use with Intensity Modulators Only)
When driving an intensity modulator, the MX10A and MX40A provide four modes for bias control. Users can select whether to use the peak, null, or quadrature point of the transfer function as the set point. Additionally, a manual mode allows the user to select any point of the transmission function to be used as the set point for the modulator bias.
These instruments can also provide bias control with or without a dither tone. For bias control with dither, users can select the amplitude and frequency that work best with their applications. For applications that require the highest SNR, the dither tone can be turned off. In this case, the bias will simply be held at the previous bias voltage. For longer term measurements, the Manual Constant Ratio mode provides another option for stabilizing the bias point. This mode operates by holding the ratio of modulator input light (Monitor 1 in the block diagram above) to modulator output light (Monitor 2) at a constant, user-set value.
On this screen, the user can control the optical output power via the Variable Optical Attenuator (VOA). The VOA can be operated in one of two modes: Constant Attenuation or Constant Output Power. In Constant Attenuation mode, the attenuation level between the output of the modulator and the output of the entire unit remains fixed, allowing power changes at the input 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.
The rear panel provides additional utility functions such as the power monitor output, RS-232, and USB ports. The USB interface is currently used only for firmware upgrades that are made available on the Thorlabs website. Future revisions of the firmware will provide for remote control of the instrument’s functions.
|1||Touchscreen Display and Control|
|2||Value Adjustment Knob|
|3||Earth Ground Port for ESD Wrist Strap Banana Plug|
|4a||Laser In for External Laser Source,
Accepts PM Fiber with FC/PC Connector
|5a||Laser Output to Modulator Input,
Accepts PM Fiber with FC/PC Connector
|6b||Return from Modulator Output,
|7b||Optical Out: Final Optical Output,
|8||Amplifier RF Out: Signal to Modulator,
|9||Bias Output to Modulator,
|10||Amplifier RF In: Signal Input to Amplifier,
|1a||I/O Control Port
Outputs from Three Integrated Power Monitors
|2a||RS-232 Control Port|
|3||USB Port (Type B)|
|4||AC Power Cord Connector|
|6||AC Power Switch|
The I/O connector provides analog outputs from the three power monitors.
|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|
The RS-232 connector is provided for firmware upgrades and will support remote operation in the future.
The USB connector is provided for firmware upgrades and will support remote operation in the future.
Each Modulator Driver includes:
Control the Modulator Drivers Remotely via Serial Commands
Serial commands sent to the MX10A or MX40A modulator driver can control the functionality of the internal RF amplifier, EO modulator bias controller, 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 MX10A or MX40A. 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 MX10A or MX40A. The touchscreen interface remains active while the modulator driver is controlled remotely. Descriptions of how to connect a controlling computer to the modulator driver, 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 Modulator Drivers
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 modulator driver remotely. It opens a connection to the laser source and sends commands in response to buttons clicked by users. Commands sent to the MX10A or MX40A, 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
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.
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.
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:
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.
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.
Customization options include internal laser sources, operating wavelength ranges, optical fiber types, and amplifier types.
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.
Customization options include single mode and multimode optical fiber options, where applicable, and detectors optimized for time or frequency domain operation.
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.
Customization options for the pulsed lasers include emission wavelength, optical output powers, and sub-nanosecond pulse widths.