Fast Wavelength-tunable Laser Based On Silicon Substrate

As the rapid growth of communication network traffic,optical fiber communication technology has emerged because of its large bandwidth capacity and low transmission crosstalk,it has been rapidly applied to communication networks,and the communication network has a trend of all-optical networks.Optical switching is a key link in an all-optical network.Among them,optical packet switching technology has been widely concerned for its advantages such as high speed,large capacity,high bandwidth utilization,and high configurability.Optical packet switching technology requires the realization of nanosecond-level switching rates,so the wavelength-tunable lasers used in optical packet switching must also be able to switch wavelength in nanosecond-level,so as not to cause too long time delays in the network,which is effective reduce the congestion delay of the optical network and increase the transmission capacity.Silicon-based photon integration technology has the advantages of low cost,easy integration,and compatibility with CMOS technology.It is an important way to achieve future high-speed optical communications.So the main research purpose of the paper is to realize silicon-based high-speed wavelength-tunable lasers with wavelength switching rates in nanosecond.This research is based on two silicon-based materials.The first one is PIN junction forming from ion-doped silicon materials and using the plasma dispersion effect to change the refractive index of the silicon waveguide.The second one is based on thin silicon-based lithium niobate(LN)film,which uses its intensive electro-optic effect to make the refractive index of the material change linearly by voltage.The main researches are as follows:1.A silicon-based PIN junction high-speed wavelength tunable laser is designed.The external cavity of the laser is based on the insulator silicon platform composed of a dual-ring resonator and racetrack micro-ring resonator includes a rib waveguide modulation arm doped with ions at both sides.Mode selection of the external cavity is achieved by the vernier effect between the two rings,and the laser wavelength is tuned by the voltage applied to the electrodes on the micro-ring.2.A high-speed tunable wavelength laser based on thin silicon-based lithium niobate film is designed.The external cavity of the laser is based on a thin silicon-based lithium niobate film platform,which is composed of a double-ring resonator,and electrodes are made on both sides of the racetrack micro-ring.The laser stimulated light wavelength was tuned by the electro-optical effect of the lithium niobate material.The 14 nm tuning range was achieved in the simulation.3.Fabrication and test on thin silicon-based lithium niobate film waveguide devices.The etching process parameters of the silicon-based lithium niobate film were obtained by experiments.Directional couplers and single-ring resonators are fabricated and tested individually.The results show that the coupling coefficient of the directional coupler varies with the waveguide spacing and the coupling length;the transmission and the tuning rate of the single micro-ring resonator were obtained,the optimal tuning rate of the single micro-ring resonator reached 6.97pm/v.4.Gold wire bonding was performed on the thin silicon-based lithium niobate film chip,and the characteristics of the filter spectrum of the double-ring resonator and the spectral shift with voltage were tested separately.The dual-ring resonant external cavity was side-coupling with a semiconductor optical amplifier.After the alignments of optical paths,testing the spectrum of the laser and its tunable characteristics.Currently 3nm turntable range is measured in testing laser.