All-Fiber Image-Rejection Receiver Front-End for Optical Communication Systems Using High-Birefringence and Polarizing Fibers

Abstract

In this paper, we investigate in detail the conditions necessary for proper image-rejection operation and characterize the performance of a single detector, all-optical image-rejection mixer for use in heterodyne receivers. The principal component of the all-optical image-rejection receiver is a length of high-birefringence fiber. A polarizing fiber is also considered as an alternative to the high-birefringence fiber. The image-rejection performance is based on meeting certain required ideal conditions for polarization states of the desired and image channels. To study this, we examine, using the Stokes parameter approach, the evolution of certain figures of merit with distance in single-mode high-birefringence and polarizing fibers. Due to the nearness of the frequencies of the desired, image, and local oscillator (LO) signals, the mismatches from the ideal conditions are very small compared to the beat lengths. Therefore, there is negligible receiver error rate performance degradation. Our results indicate that this all-optical image-rejection receiver implementation is a robust device that is also highly insensitive to temperature variations.