PolaDetect POD-201 In-Line Fiber-Coupled Polarimeter

The POD-201 is an in-line, fiber-coupled polarimeter that uses four channels to measure the four Stokes parameters at the same time. From these it reports the instantaneous state of polarization (SOP), degree of polarization (DOP) and power of the light in the fiber. The standard configuration is a two-port in-line version, so a signal can be monitored without interrupting it. The manufacturer has discontinued the POD-201 and lists the High Speed Polarimeter POD 2000 as its replacement.

FPGA electronics give a sampling rate of up to 4 MS/s, fast enough to track rapid polarization changes. A USB 2.0 interface transfers data to a computer at up to 30 MB/s. The instrument also has averaging and statistical functions. These can measure the time-averaged DOP of a polarization scrambler, track how far the SOP drifts from a reference value, and record the maximum and minimum values of a parameter over a measurement period.

Software and integration

The included PolaView software shows SOP information on a Poincaré sphere or on a virtual oscilloscope. It adds SOP markers for angle measurement, an SOP replay function, extended triggering in oscilloscope mode, PER measurement, and streaming of SOP-versus-time data to a file. The front panel has an OLED display for setup and readings. A configurable analog output for SOP, DOP or power lets the instrument connect to automated test systems.

Calibration

A built-in user calibration program improves DOP and SOP accuracy at specific wavelengths and temperatures. With a suitable light source, the POD-201 can also measure polarization extinction ratio (PER), for example when aligning PM fiber to laser sources.