Cascaded SSB comb generation using injection-locked seed lasers

We investigate a novel concept of cascaded single side band (SSB) comb generation for improving the carrier-to-noise ratio (CNR), which degrades when the bandwidth of the SSB comb becomes wider. Wavelength-multiplexed seed lasers are simultaneously modulated in a recirculating frequency shifter loop with an SSB modulator, an Er-doped fiber amplifier, and a fiber Bragg grating whose reflective notch filter nature enables seed lasers to be synchronized through the injection locking (IL). A maximum CNR improvement of 11.3 dB is experimentally demonstrated under the IL condition. The proposed technique effectively improves the CNR of wide-bandwidth SSB combs.