Low-loss InP-based photonic crystal waveguides and resonators

Abstract

We report on low-loss light propagation at the communication wavelength of 1.55 µm through straight two-dimensional photonic crystal waveguides patterned into InGaAsP/InP heterostructures. The linear defect waveguides along the ΓK direction of a triangular lattice of air holes were etched deeply into the semiconductor by Cl₂/Ar electron cyclotron resonance reactive ion etching. Efficient waveguiding was observed for both polarization directions, although a photonic band gap exists for only one of the polarization states. Propagation losses, determined by the Fabry-Perot resonance method, are as low as 0.2 dB/mm and 1.5 dB/mm for waveguides based on seven and three missing rows of holes, respectively. Waveguide resonators with 100 GHz channel spacing and quality factors up to 15,000 have been realized by inserting photonic crystal mirrors into the waveguides. The dispersion of the resonators was measured using a phase shift technique. Values for the group velocity dispersion range from -250 ps/nm to +250 ps/nm at wavelengths around 1.55 μm, which is sufficient to compensate for the dispersion of 15 km standard single-mode fiber. Controlling the device temperature allows to tune the dispersive properties of the devices.