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High-Speed, Fiber-Optic, Linear Reference Transmitters![]()
MX65E-1310 65 GHz Reference Transmitter, 1310 nm Internal Laser MX35E 35 GHz Reference Transmitter, C-Band Internal Laser 32 Gb/s Eye Diagram from MX35E ![]() Please Wait All Reference Transmitters Include:
![]() Click to Enlarge 20 Gb/s NRZ Eye Diagram from MX35E Series ![]() Click to Enlarge 25 GBaud/s PAM4 Eye Diagram from MX35E Series ![]() Click to Enlarge 40 Gb/s NRZ Eye Diagram from MX35E Series ![]() Click to Enlarge 56 GBaud/s PAM4 Eye Diagram from MX65E Series Features
Thorlabs' all-in-one linear reference transmitters are based on proven lithium niobate (LiNbO3) modulator technology driven by high-fidelity RF amplifiers. They are designed for high-speed fiber optic test and measurement applications. These user-configurable systems integrate a Mach-Zehnder intensity modulator (MZM) with fully featured bias control, a tunable or fixed-wavelength laser source, RF amplifier, and variable optical attenuator. These instruments are ideal for use in either an R&D laboratory or in a manufacturing environment for linear applications that require frequency responses up to 35 GHz (MX35E series) or 65 GHz (MX65E series), including high bit-rate modulation schemes that rely on multi-level encoding, such as PAM4. The transmitters on this page are based on the use of an RF amplifier that provides a linear relationship between the input and output voltages. Note, however, that the linear range of the whole system is still limited by the non-linear response of the lithium niobate (LiNbO3) modulator. As a result, large RF output signals will experience some compression, which can be advantageous in some applications. Internal Laser System Connections We offer a selection of microwave cables and adapters for incorporating these transmitters into a system. Control We also offer digital reference transmitters with speeds up to 40 Gb/s and optical transmitters based on phase modulators. Please see the Selection Guide tab above for all of our transmitter instruments. ![]() Click to Enlarge Block diagram Showing Internal Setup of the High-Speed, Linear Reference Transmitters. ![]() Click to Enlarge This plot demonstrates the usable bandwidth provided by each series of linear reference transmitters.
![]() Click to Enlarge Linear amplifiers provide a linear relationship between voltage input and output. Different line slopes indicate different gain settings in the MX35E series. Gain is user-adjustable in 1 dB increments.
System OverviewThese Linear Reference Transmitters are fully integrated and contain both the laser source and the lithium niobate (LiNbO3) Mach-Zehnder intensity 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 can be seen at 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. 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. ![]() A Block Diagram of the Internal Setup of the High-Speed Reference Transmitters Instrument ControlThe 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. The home screen is shown in Figure 1. It is organized into three main sections: ![]() Click to Enlarge Figure 1: Home Screen of the MX35E Series
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![]() Click to Enlarge Figure 3: System Wavelength Selection 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 Tech Support. 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 3, to change the power monitor calibration wavelength to the value closest to the wavelength of the laser source being used. ![]() Click to Enlarge Figure 5: Linear amplifiers provide a linear relationship between voltage input and output. Different line slopes indicate different gain settings in the MX35E series. Gain is user-adjustable in 1 dB increments. ![]() Click to Enlarge Figure 4: Linear RF Amplifier Settings Screen for the MX35E Series Linear RF AmplifierThe amplifier used in these reference transmittes is a linear amplifier that accurately reproduces the input signal with minimal distortion. In addition, the MX35E series has adjustable gain that can be controlled from the Amplifier Settings page shown in Figure 4. This allows for linear amplification for a wide range of input signal levels before being applied to the RF input port of the modulator. Figure 5 shows how the gain setting changes the slope of the output vs. input signal relationship. Note, however, that the linear range of the whole system is still limited by the non-linear response of the lithium niobate modulator. See the specifications in the Specs tab and manual for signal limitations in this regard. Modulator Bias Controller![]() Click to Enlarge Figure 7: Bias Settings Screen ![]() 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 set point, 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 Set Point 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 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 set points. 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![]() 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 11, 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 PanelThe 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 (
I/O DB15 Connector![]() The I/O connector provides analog outputs from the three power monitors.
RS-232 Connector![]() The RS-232 connector is included to support future remote operation that will be enabled by future firmware upgrades.
USB Type B Connector![]() The USB connector is provided for firmware upgrades and future remote operation. ![]() Click to Enlarge Each reference transmitter offers the option to customize the color of the underbody accent lights or turn them off. Included with Thorlabs' High-Speed Reference Transmitters:
Software for the Linear Reference Transmitters![]() Click to Enlarge The GUI of the Remote Control Software Tool Control Our Reference Transmitters Remotely via Serial Commands Application Demonstrating GUI-Based Remote Control of Our Reference Transmitters ![]() Janis Valdmanis, Ph.D. Optics Ultrafast Optoelectronics General Manager Custom and OEM OptionsWhen 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 UnitExplore 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. ![]() Click to Enlarge The MX40B Digital Reference Transmitter Design, Manufacturing, and Testing CapabilitiesThorlabs' 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:
Overview of Custom and Catalog ProductsOur 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 InstrumentsTo 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. Fiber-Optic ComponentsOur 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. Free-Space InstrumentsOur 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.
Selection Guide for Transmitter InstrumentsThe 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 ![]()
The transmitters are designed for linear applications that require frequency response up to 35 GHz, which makes them compatible with high bit-rate modulation schemes that rely on multi-level encoding, such as PAM4. The RF amplifier has user-adjustable gain from 10 dB to 23 dB, which changes the slope of output versus input voltage curves. The adjustable gain control allows the output of the amplifier to remain linear across a broad range of input signal levels. Please note: The MX35E-LB and MX35E-1310 transmitters will ship from the US within 7 to 10 days of placing an order if all component parts are available. ![]()
These transmitters have a usable bandwidth of 65 GHz, which makes them compatible with high bit-rate modulation schemes that rely on multi-level encoding, such as PAM4. The system has a smooth response over its entire frequency range (see the graph on the Specs tab). The RF amplifier has a fixed gain of 11 dB. Please note: The MX65E and MX65E-LB transmitters will ship from the US within 7 to 10 days of placing an order if all component parts are available. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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