Noninterferometric optical phase-shifter module in phase-shifted optical quantization

A noninterferometric configuration for an optical phase-shifter module (OPSM) is presented and demonstrated, which is a key component in phase-shifted optical quantization (PSOQ) systems. In a PSOQ system employing such an OPSM, the input electrical analog signal is applied on two LiNbO3 intensity modulators in parallel, and the OPSM takes the outputs of the intensity modulators as its input and yields N-channel optical outputs, which are thresholded to generate digitized values of the input analog signal. The feasibility of this OPSM configuration is demonstrated by a proof-of-principle PSOQ experiment, in which a 2.5-GHz single tone is applied to the modulators and 16 transmission curves are recorded. Based on these transmission curves, software sampling indicates that an effective number of bits equal to 4.17 is attainable for a frequency as high as 2.5 GHz. Benefits of such an OPSM are easier control and high precision of desired phase shifts. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3089884]