Study And Design Of Multi-carrier Light Source Integrated Chip

In order to increase the transmission capacity of optical fiber communication systems, multi-carries optical communications have been deeply researched by the scientists around the world. Multi-carries light source integrated chip is one of the key components in multi-carries optical communications system. There are many methods to generate a multi-carrier light source, wherein the scheme for multi-carries light source generation based on optical frequency comd has a simple structure, adjustable numble of carries, adjustable frequency interval, the carrier frequency stability, etc. become a hotspot. This article focuses on the generation of optical frequency comb based on a multimode interference coupler.Firstly, this paper describes the development of optical fiber communication, several typical schemes for multi-carrier light generation and the application of OFC in two areas, namely the multi-carrier light generation and the Nyquist pulse generation. And then, based on the theory of electro-optic modulator and multimode interference coupler, we propose two different schemes for optical frequency comb generation by using multimode interference coupler and verify the scheme through simulation. The major contents conclude that: we introduce a single-side-band(SSB) modulator based on a 1×3 multimode interference coupler, and propose a scheme for optical frequency comb generation by using a recirculating frequency shifter based on the SSB modulator. Through analyzing the working principle of the SSB modulator, and deriving theoretical expression formula. We using the VPI simulation software to verify the scheme. Theoretical and simulation results show that the SSB modulator implemented the carrier suppressed of SSB modulation with side-band suppression retio more than 20 d B. An OFC with more than 40 comb lines, and frequency interval of 5 GHz has been generated by the recirculating frequency shifter. We introduce a new MZ modulator based on a 1×4 multimode interference coupler, and propose a scheme for optical frequency comb generation by two cascaded the new modulator. Through analyzing the working principle of the modulator, and deriving theoretical expression formula. We also using the VPI simulation software to verify the scheme. Theoretical and simulation results show that by adjusting the bias voltages and the power of the microwave signal, we can achieve an OFC having 5 comb lines within a spectral flatness of 0.1 d B. When cascaded with another modulator, 25 comb lines with spectral power variation less than 0.2 d B are obtained. At the same time, we verify that the frequency spacing of the OFC generated by the program is adjustable. And through simulation, an OFC with frequency spacing 5 GHz and 8GHz can be generated respectively.