A novel scheme for noise suppression in optical comb generation

A novel scheme by inserting an Asymmetry Mach-Zehnder Interferometer(AMZI)in Recirculating Frequency Shifter (RFS) loop is proposed. Using this scheme, tone-to-noise ratio(TNR)of Optical Frequency Comb can be enhanced by suppressing the accumulated amplified spontaneous emission (ASE) noise. An optical frequency comb with 49 tones based on this method was generated. The experimental results are in good accordance with the theoretical and numerical analyses. It is shown that TNR of the optical frequency comb generated by the improved scheme can be as high as 37.5dB.