Optical frequency comb generation based on spectral broadening of a phase locked dual-wavelength microcavity laser

A highly coherent optical frequency comb (OFC) based on spectral broadening of a phase-locked dual-wavelength microcavity laser is presented. By directly modulating the microcavity laser to generate multiple sidebands, the cross-injection locking of the dual modes is achieved and the beat-signal linewidth is improved from 13.5 MHz to less than 100 Hz. Subsequently, 21 flat comb teeth in a +/- 3 dB power variation are achieved by combining a phase modulator. Finally, an OFC with a bandwidth of 16 nm is successfully realized by narrowing the optical pulse and spectral broadening in a commercial nonlinear optical fiber. The repetition rate has a low phase noise of -102 dBc Hz(-1) at 10 kHz offset, demonstrating the generated OFC has a high degree of coherence.