Thorlabs High-Speed, Fiber-Optic, Linear Reference Transmitters

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.

• Turnkey Reference Transmitter Solution
• Linear RF Amplifier
• Integrated Laser, Intensity Modulator, and Optical Power Control
• External Loop-Back Cables Support Custom Configurations
• 35 GHz Models with Differential Signal Input
• Control via Intuitive Touchscreen Interface or Remotely Using USB or RS-232 Connections
• Custom Systems Available 

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 (MX35 series), 50 GHz (Item # MX50E-850), or 65 GHz (MX65 series), including high bit-rate modulation schemes that rely on multi-level encoding, such as PAM4. The MX35D series of linear transmitters feature differential signal inputs, which enable the use of low-noise differential sources.

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
Each reference transmitter has a built-in telecom-grade laser. The MX35 and MX65 series transmitters are available with an internal C-band tunable external cavity laser, L-band tunable external cavity laser, or fixed-wavelength 1310 nm distributed feedback (DFB) laser, while the MX50E-850 transmitter includes an 852 nm fixed-wavelength DFB laser. MX35E and MX35D series reference transmitters with an integrated 850 nm fixed-wavelength laser are also available upon request.

The internal C- and L-band lasers are tunable on the ITU 50 GHz grid and incorporate a frequency offset option for fine tuning by ±30 GHz in increments of 1 MHz. A dither feature for wavelength stabilization is available in both tunable internal laser options (see the Operation tab for more information). An external laser source between 1250 and 1610 nm can also be used to provide the optical input for the MX35 and MX65 series transmitters.

System Connections
The laser input port on each reference transmitter (excluding Item # MX50E-850) 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). The MX50E-850 transmitter does not provide a laser input port. Instead, the internal 852 nm fixed-wavelength DFB laser is spliced directly to internal optical components because at shorter wavelengths, it is critical to maintain perfect core to core alignment of the fibers to limit insertion loss and maintain a high polarization extinction ratio (PER).

Each fiber bulkhead accepts FC/PC connectors. The amplifier RF port connectors type are either SMA or 1.85 mm (V), depending on the frequency response of the device. See the Front & Back Panels tab for more information.

A selection of microwave cables and adapters is offered for incorporating these transmitters into a system.

Control
These reference transmitters 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. 

We also offer digital reference transmitters with speeds up to 40 Gb/s and optical transmitters based on phase modulators.

40 Gb/s NRZ Eye Diagram from MX35E Series

25 Gbaud/s PAM4 Eye Diagram from MX35E Series

Download Applications Note: Transmitter Optimization for PAM4 signals.