Study On Tunable Laser Based On Reconstruction-Equivalent-Chirp Technique And Package Technique

With the development of Internet,the emergence of 5G,users'demand for multimedia and broadband new services is gradually increasing,which requires the support of high bandwidth and high efficiency optical switching network.Tunable laser is the core optoelectronic device in the high speed optical switching network.Besides,tunable laser plays an important role in sensing,laser radar and other fields.Although a variety of tunable laser sources have been developed,they all have disadvantages.Facing this huge demand,how to manufacture tunable laser with low cost and high efficiency and improve its tuning performance is of great research significance.In this paper,the innovative matrix laser array is designed and fabricated based on the reconstruction equivalent chirp(REC)technique,which solves existing distributed feedback lasers'some problems.In addition,we study the package method of the tunable laser.In particular,the approach of changing the tuning performance of the laser by using the submount is studied,which can reduce the cost of energy in the application.The main contents and findings of this paper are as follows.(1)A matrix laser array based on REC technique is proposed.This structure optimizes the traditional in-parallel and in-series structures to obtain higher output power and avoid the crosstalk of adjacent lasers.Under the condition of environment temperature as 293 K and injection current of 70 mA for each laser,the four-channel laser array can achieve the wavelength-spacings of 2.4 nm,and the wavelength control accuracy is within±0.12 nm.The channels have good single-mode characteristics and side-mode suppression ratio(SMSR)above 45.2dB.According to the measurement results of 40 in-series laser arrays(160 lasers),wavelength deviations of 93.1%lasers are within±0.2 nm,which proves that REC technique can accurately control the laser wavelength.(2)The packaging process of the laser and the influence of different submount on the tuning performance of the laser are studied.The impact of submount properties on laser performance is analyzed in detail by heat conduction theory and simulation software,and the conclusion is verified by welding chips on a AlN submount and a SiO₂submount respectively,comparing the experimental results.The DFB-MLA(Multi-wavelength distributed feedback laser array)chip achieves a better tunable effect as the lasers can be tuned at 3.5-3.7 nm per channel from 50 to 120 mA with stable output power of over 7 mW as contrasted with the laser on the AlN submount being tuned at1.4-1.5 nm per channel.And the chip has a side-mode suppressing ratio(SMSR)of over35 dB and strong stability of wavelength in the repeated experiments.Compared with the traditional scheme of tuning the laser wavelength by changing the temperature of the semiconductor cooler,this method can change the wavelength faster,saves a lot of energy and reduces device cost.