March 2022; May 2020

PDL measurement <0.004 ... >60 dB; PMD measurement <10 fs ... 10 ps with standard deviation ≤3 fs; polarization tracking during laser frequency sweep

PMS1000 is a combination of PM1000 polarimeter and EPS1000 polarization scrambler/transformer and measures Mueller matrices. PDL can be measured from <0.01 dB to >60 dB. When an LU1000 laser unit is coupled to it, polarization mode dispersion (PMD) can be measured with differential group delays (DGD) down to the low fs range and standard deviation of a few fs.

A patchcord with fixed layout/bends serves as a reference. The same patchcord was tested >100 times as device-under-test, each time with different polarization transformations, due to different fiber layouts/bends: Perceived patchcord PDL was <0.03 dB for measurement times of 5 us, and <0.004 dB for measurement times of 100 ms. At the high end, we easily measure PDL >60 dB.

Pieces of polarization maintaining fiber (PMF) were tested, 6 times each. To vary polarization transformations from one measurement to the next, always one SMF connector was disconnected, rotated by different multiples of 360° and reconnected. Even the 7 mm long PMF with an expected DGD of ~9.4 fs was clearly detected. With 50 GHz frequency steps, DGDs up to 10 ps were measured unambiguously.

Approximate Differential group delay (DGD)
PMF length meanstandard deviation
0 mm (no PMF) 3 fs1 fs
7 mm 12 fs1.5 fs
25 mm 34 fs3 fs
49 mm 66 fs3 fs
580 mm 801 fs2 fs
780 mm 1032 fs2 fs
2600 mm 3540 fs3 fs
7000 mm 9432 fs3 fs

Polarization can be controlled during laser frequency sweep, by max./min. intensity search or by error signal from polarimeter.