Simple and compact V-cavity semiconductor laser with 50×100 GHz wavelength tuning

We report simple and compact V-cavity semiconductor laser capable of full-band wavelength tuning. A half-wave coupler is used to obtain high side-mode suppression ratio (SMSR) without any grating or epitaxial regrowth. Temperature induced gain spectrum shift is employed in combination with the Vernier tuning mechanism to extend the wavelength tuning range beyond the free spectral range limit. Wavelength tuning of 50 channels at 100GHz spacing with SMSR up to 38 dB has been demonstrated. We show that with a temperature variation of 35°C, the tuning range can be extended by about 15 nm, in contrast to 0.1 nm/°C for thermo-optic tuning range in grating based lasers. At a fixed temperature, consecutive wavelength tuning of 31 channels was achieved. The response time of the channel switching under the current-tuning regime is measured to be about 20μs. The large tuning range that can cover the full C-band will enable such a simple, compact and potentially low-cost tunable laser to be used in wavelength-agile access and data center networks.