Relative intensity noise measurements of a widely tunable sampled-grating DBR laser

The intensity noise of a sampled-grating distributed Bragg reflector laser with 50-nm tuning range and 45-dB side-mode suppression ratio has been measured. The resonance frequency, damping factor, and modified Schawlow-Townes linewidth are extracted from the noise spectra. At high output power, the relative intensity noise (RIN) of the laser is below the photodiode shot noise limit, which is -160 dB/Hz. The laser has uniform shot noise limited RIN properties along the whole tuning range. The maximum resonance frequency is 5.4 GHz at a bias current of 120 mA and the K factor is 0.58 ns.