Document #: GP-UM-POD-001-13
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Section 2. Overview:
G
eneral Photonics’ in-line polarimeter (PolaDetect) is specially designed for high-speed,
low cost polarization monitoring without interrupting data traffic. It outputs four voltage
signals for calculating both the degree of polarization (DOP) and the state of polarization
(SOP) of the light passing through the device. The measurement applies to the state of the
light at the input end of the polarimeter. A calibration matrix is provided with every
device at a specific wavelength for the calculation.
PolaDetect is ideal for integrating into polarization monitoring and polarization
stabilization modules to increase their operation speeds. It can also be used in
polarization characterization instruments. An integrated preamplifier circuit board
provides analog signals for SOP/DOP calculation, feedback control, and computer
interface.
Section 3. Device description
General Photonics’ Polarimeter includes four photodetectors, which output four
photovoltages (or photocurrents) for polarization analysis. The SOP and DOP of an input
light signal can be readily calculated using the four photovoltages and a 4x4 calibration
matrix. In general, the calibration matrix is wavelength dependent, so calibration matrices
are provided at 10 nm intervals. For example, for the 1550 nm band, five calibration
matrices are provided: for 1520 nm, 1530 nm, 1540 nm, 1550 nm, and 1560 nm
operation, respectively. Each matrix is for a wavelength band of +/- 5 nm.
Fig. 1
Photograph of a PolaDetect
NOTE: the resulting SOP is that at the input entrance of the polarimeter.
As illustrated in Fig. 1, PolaDetect consists of two main parts: the optical module and the
electronic preamplifier board.
