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Recently, a number of high-speed optical clock generation technologies have been developed due to their potential useful applications in different fields. Here, we propose a new terahertz optical clock generation technique with tunable repetition rate and central wavelength. The proposed optical clock generator consists of an frequency comb light source and a variable-bandwidth spectrum shaper (VBS). The VBS can generate arbitrary repetition rate pulse trains and waveform by controlling each spectral mode. We experimentally demonstrated optical clock generation with repetition rates of 1.28, 2.56, 3.0, and 4.0 THz.

Abstract:We performed a simulation of optical code generation and processing to determine the number of discriminable codes, which depends on the number of chips and the chip rate. Based on an actual optical binary phase shift keying (BPSK) code generation and processing system, the characteristics of devices in the code generation and processing with threshold processing were considered in this simulation. To handle variable BPSK codes, we used LiNbO 3 (LN) modulators as an optical code generator and a transversal filter (TVF) as an optical code processor. We found that BPSK codes with 2-6 chips, 10, 20, 40 Gchip/s had sufficient threshold margins for code discrimination in the simulation, and this result was in good agreement with experimental results. We performed experiments 4 chip, 10 Gchip/s code generation and processing, and we experimentally confirmed the number of discriminable codes is 8.

We demonstrated arbitrary optical pulse shaping and generation by spectral control and were able to control the phase and amplitude of the spectrum with 10 GHz resolution in the entire C-band, with rectangular pass-bands, using a variable bandwidth spectrum shaper. The experimental results of waveform generation were almost identical to the calculated results. We also experimentally demonstrated time-spread 200 Gchip/s, 10 Gbit/s, and 8-chip optical binary phase shift keying (BPSK) code generation and processing based on spectral control. To demonstrate applications of this spectrum controller to tunable optical label processing, we performed experiments and simulated label generation and processing by controlling the spectrum.