Application Of Waveguide Bragg Gratings In Passive Filters And Semiconductor Lasers

The global information technology is in an active period of innovation.Driven by new businesses and applications,the data flow is explosive growth,which presents a severe challenge to the bandwidth,capacity,cost and power consumption of the underlying interconnected systems and devices.In order to realize optical network operation with all-band,high-speed,high-capacity and intelligent,photonic technology is going integrated which called photonic integrated circuits?PICs?.Based on PICs,the volume,power consumption and cost of the photonic devices can be greatly reduced and the performance can be improved.At present,the PICs are mainly based on indium phosphide?In P?,silicon?Si?and silicon nitride?Si₃N₄?material system.Waveguide Bragg grating?WBG?is usually used as a filter device with the characteristics of small volume and high integration.Different spectral responses can be achieved by changing the period,index and phase of the WBG,which is widely applied to PICs.WBG has been used to different active/passive devices,like laser,modulator and mode converter etc.With the improvement of the device performance,it hopes that the WBG can be smaller in size,simpler in fabrication and better in performance.This paper introduce the application of the WBG in passive filters and semiconductor lasers.The method to simulate the WBG was introduced,and the paper gives the simulation results of different WBG according to the method.This paper also introduce the simulation model in time and frequency domain of the distributed feedback?DFB?laser,and give the simulation results of the DFB laser with different WBG structures according to the method.In addition,the fabrication of the semiconductor laser is also introduced.According to the previous research in this paper,we proposed two new passive device structure and active device model:1?This paper proposed an on-chip integrated narrowband reflector?NBR?based on antisymmetric Bragg grating.The NBR is made up of four parts:single mode waveguide?SM-WG?,taper,?phase shifted antisymmetric Bragg grating??-PS-ASBG?and uniform Bragg grating?UBG?.The?-PS-ASBG achieve the conversion between the TE0 and TE1 modes and light resonance,the reflected light is TE1 mode and the transmission light is TE0 mode.There is a transmission peek at the Bragg wavelength in the transmission spectrum.UBG is used as a mirror to reflect the TE0 mode that transmitted from?-PS-ASBG.SM-WG and taper are used to radiate the TE1 mode.Different from traditional NBR,the bandwidth of the proposed structure decreases when the grating coupling coefficients increases.The calculate3-d B bandwidth is 0.16 nm when the grating length is 400?m.In addition,the best parameters of the device are obtained through simulation of each parts,which lays a foundation for the follow-up research.2?This paper proposed a model of narrow linewidth semiconductor laser?NLSL?based on the new NBR.The NLSL is made up of a gain chip coupled with the NBR by spot size converter?SSC?.One facet of the gain chip is coated reflective film with a certain reflectivity and the other facet is coupled with the NBR.The NBR is a filter to choose a specific wavelength for resonance to achieve single mode operation.In addition,the NBR increases the effective cavity length of the laser,which delay the resonance time of the photonics,the linewidth of the laser can decrease.The traditional NLSL adopted NBR with week grating strength,which the size of the device up to millimeters.The size of the proposed NLSL reduce to micrometers,which is benefited to the integration and encapsulation.According to the simulation results,the NLSL has good performance in single-mode operation and power output.The calculated 3-d B linewidth of the NLSL is less than 10 KHz.The effects of the performance by the coupling efficiency between the NBR and gain chip and the reflectivity of the NBR are also analyzed in this paper.