We present a tunable multi-channel optical true time delay (OTTD) using frequency interval tunable multiwavelength light source (MWLS). The frequency interval of MWLS can be flexibly tuned by programming a driving radio frequency (RF) signal. By using this tunable MWLS, the time delay difference (TDD) of multi-channel OTTD can be flexibly tuned with time in different function forms. The TDD of linear tuning with variation range of 61.84-119.71 ps and sinusoidal tuning with variation range of 60.97-87.76 ps with time are experimentally demonstrated.
We present a step-swept light source with high linearity and tunable frequency step based on the lightwave synthesized frequency sweeper (LSFS). Different from the traditional internal modulation, this light source can effectively avoid complex frequency-calibration and deduce the spectrum stitching error by using the external modulation and a time delayed spectrum stitching technique. Experimentally, a k-space swept with > -0.99997 swept linearity is achieved. The swept range are 5.135 nm with 10 GHz swept step and 3.902 nm with 7.5 GHz swept step. The spectrum stitching-error is less than 2.92% and 0.65% respectively.