A novel optical ridge waveguide using calcium barium niobate (CBN) with a high electro-optic coefficient on silicon substrate is proposed for the design and realization of the next-generation hybrid modulators with short length and low driving voltage. To overcome the etching difficulty of CBN, the design of a waveguide, including an elevated CBN layer based on etched silicon dioxide, is presented. Fabrication of a thick 2.5-µm CBN layer is performed using pulsed laser deposition. Deposited silicon dioxide on the sides and top of the CBN reduces the waveguide loss as low as 3.44 dB/cm, measured using a cutback method. Good agreement between the mode profiles of the simulation and measurement is obtained.
Soliton generation in optical fibers has been generally studied through the launch of pulses with sufficient power. Also, soliton generation can take place through modulation instability and with the amplification of noise. In this paper we will derive the gain of modulation instability and show soliton evolution through the amplification of a seeded noisy signal, which describes the generation of amplified ultrashort solitons from weak-modulated CW laser source by normalized numerical simulations.
In this paper, we present the effect of grating structure on Relative Intensity Noise (RIN) in Distributed Feedback (DFB) laser diode. We analyze the noise in three types of grating shape including longitudinally uniform, concave and convex depth. It is shown that the concave grating against uniform and convex structure is suitable for reducing the Spatial Hole Burning (SHB) effect, but is not appropriate for low noise DFB lasers. According to the results of analysis, in uniform grating, RIN decreases when the corrugation depth increases. In concave and convex structure, grating depth is composed of fixed and variable parts. When fixed part of grating depth is constant, increasing variable amplitude of grating reduces RIN and when the variable part of grating is constant, increasing fixed part of grating reduces RIN. In all of the three type structures, RIN for the symmetric grating is lowest. Also with decreasing RIN, relaxation oscillation frequency decreases and when the SHB effect occurs, the rate of this decreasing is low. We conclude a special shape of grating that has low SHB effect and low noise in optical communication systems.