Abshract-Experimental results of a wideband heterodyne second-order optical phase-locked loop with 1.5 p m semiconductor lasers are presented. The loop has a bandwidth of 180 MHz, a gain ol' 181 dBHz, and a propagation delay of only 400 ps. A beat signal of 8 MHz linewidth is phase locked to become a replica of a microwave reference source close to carrier with a noise level of -125 dBc/Hz. The total phase variance of the locked carrier is 0.04 rad' and carriers can be generated in a continuous range from 3 to 18 GHz. The loop reliability is excellent with an average time to cycle slip of 10" s and an acquisition range of 640 MHz.

No abstract

We have measured the refractive index of InP and of liquid-phase-epitaxy–grown InGaAsP layers on InP in the transparent wavelength region using a Brewster-angle method. The dependence of the refractive index on material composition and light wavelength has been investigated for near-lattice-matched samples and compared with theoretical models. We show that both an interband transition model and a single effective oscillator model can be used to calculate the refractive index if the parameters used in the calculations are chosen properly. We have also studied the variation with lattice mismatch by varying the growth temperature. We found that a lattice mismatch variation of 10−3 corresponds to a change in the refractive index of approximately 0.02 for λg=1.20 μm layer band gap at λ=1.30 μm wavelength. Finally, we have measured the refractive index of doped InP substrates and found refractive index reductions, due to doping, of up to 0.05.

No abstract

No abstract