Design of Tuneable Laser With Interleaved Sampled Grating Rear Mirror

We present the design of a widely tunable laser diode which employs a coupled-cavity sampled grating rear reflector with interleaved connections for use as the wavelength discrimination and tuning enhancement element. Simulations show that this new reflector in conjunction with a cleaved output facet for the laser yields a source with a tuning range of >50 nm. Due to the absence of a front grating reflector a highly uniform output power can be obtained for a fixed gain current with a 0.35 dB variation achievable for an output power of +15 dBm across 195 modes on a 25 GHz spacing. The SMSR for all modes is close to 40 dB. The device can be integrated with a wideband front reflector at the expense of an increase in threshold current and a reduced tuning range.