Bi-directional comb-fiber architecture for resolution improvement of optical quantization employing soliton self-frequency shift and spectral compression

We demonstrate a high-resolution quantization scheme based on soliton self-frequency shift (SSFS) and spectral compression in a bi-directional comb-fiber architecture. Our scheme is composed of a Sagnac-loop-based mirror and a comblike combination of two sections of interleaved single-mode fibers (SMFs) and high nonlinear fibers (HNLFs). The Sagnac-loop-based mirror is placed at the terminal of the bus line to reflect the optical pulses back to the bus line to achieve single-stage SSFS and three-stage spectral compression. Quantization with a resolution of 6.2-bit is obtained in the experiment, which is 1.2-bit higher than that of its uni-directional counterpart. Our bidirectional scheme can achieve higher quantization resolution with a small volume and a low cost compared with its uni-directional counterpart.