Frequency Quasi-Linear Swept Light Source Based on Multi-Frequency Time-Matched Spectrum Stitching

A novel frequency quasi-linear swept light source based on multi-frequency time-matched spectrum stitching and recirculating frequency shifter loop (RFSL) is proposed and successfully demonstrated. The seed light with different frequencies enters RFSL in turn through optical delay line to complete the frequency sweep and spectrum stitching of each band. Spectrum stitching can effectively reset the noise, suppress the accumulation of amplified spontaneous emission (ASE) noise and the spectral sideband noise in RFSL, and expand the sweep range several times without affecting the sweep linearity. A swept range of 5.227 nm is experimentally achieved with the noise range of 7.78 dB. Compared with the single-frequency sweep scheme that the noise variation is 9.03 dB, the sweep range is extended by more than three times. The Pearson's correlation coefficients (r) of the output swept signal is higher than -0.99996.