An integrated equivalent circuit model for relative intensity noise and frequency noise spectrum of a multimode semiconductor laser

Relative intensity noise (RIN) and the frequency/phase noise spectrum (FNS) equivalent circuit of a multimode semiconductor laser diode are derived from multimode rate equations with the inclusion of noise Langevin sources. FNS is an important parameter in optical communication systems, and its circuit model is presented, for the first time, in this paper. Both circuit models for RIN and FNS are integrated in one circuit. RIN and FNS are calculated as functions of frequency, output power, and mode number. It is shown that the RIN of the main mode is increased in the multimode lasers with higher mode numbers. Furthermore, we show that RIN and FNS are enhanced for higher output power. The dependency of a multimode laser diode linewidth on output power is also analyzed using the model.     

Low-loss CaxBa1−xNb2O6 ridge waveguide for electro-optic devices

Optical ridge waveguide using calcium barium niobate (CBN) on silicon substrate for the first time is designed, fabricated and characterized for future integrated electro-optic devices. To obtain single-mode propagation, the CBN thin strip is designed to be surrounded by thick silicon dioxide layer forming a ridge waveguide. Deposition of CBN film on profiled silicon dioxide introduces spatial separation which solves the CBN etching problem. Fabrication, edge polishing and near-field mode profile measurement of the waveguide are carried out. The measurement is in good agreement with the simulation and an exact loss as low as 2.15 dB/cm was obtained for the fabricated waveguide.