Polarization-sensitive plug-in optical module for a Fourier-domain optical coherence tomography system

In this manuscript we communicate a theoretical study on a plug-in optical module to be used within a Fourier-domain optical coherence tomography system (FD-OCT). The module can be inserted between the object under investigation and any single-mode fiber based FD-OCT imaging instrument, enabling the latter to carry out polarization measurements on the former. Similarly to our previous communication this is an active module which requires two sequential steps to perform a polarization measurement. Alternating between the two steps is achieved by changing the value of the retardance produced by two electro-optic polarization modulators, which together behave as a polarization state rotator. By combining the rotation of the polarization state with a projection against a linear polarizer

it is possible to ensure that the polarization measurements are free from any undesirable polarization effects caused by the birefringence in the collecting fiber and diattenuation in the fiber-based couplers employed in the system. Unlike our previous work, though, this module adopts an in-line configuration, employing a Faraday rotator to ensure a non-reciprocal behavior between the forward and backward propagation paths.