A low optical-coherent-crosstalk thin-film filter-based 1x2 fiber-optic add-drop module in a double-reflection configuration

Abstract

This paper proposes and experimentally demonstrates the use of a quadruple fiber-optic collimator rather than a dual fiber-optic collimator to form a much improved low optical coherent crosstalk 1×2 fiber-optic add-drop filter. The use of the dual fiber-optic collimator together with a single fiber-optic collimator forms a passive noise rejector that eliminates unwanted optical noises at both output ports. Our experimental results show a much improved > 39.10 dB optical isolation at the Drop port. In addition, the measured average optical losses at the Drop and the Thru ports are 1.40 dB and 1.23 dB, respectively, when only the TF is in the opticap path. A low polarization dependent loss of < 0.17 dB is also determined. Furthermore, our design concept can be used to form a high optical-isolation fixed three-port add-drop filter and a high dynamic-range wavelength sensitive variable fiber-optic attenuator.