Near-infrared Tunable Distributed Feedback Bragg Semiconductor Laser Based On Surface Isolation Grooves Structure

Tunable DFB semiconductor lasers have the advantages of small size,light weight,easily be integrated and great tunability.Distributed Feedback Bragg(DFB)lasers are used as the core light sources in the fields of quantum communication,Big Data network,Biomedical instruments,life-detection equipments and Laser defense.Gratings are introduced into traditional fabry perot cavity(FP)semiconductor lasers to form periodic perturbation,which leads to the refractive index or gain modulation in the DFB semiconductor laser for modulating mode of output laser.Refractive index and gain modulation correspond to refractive index-coupled and gain-coupled DFB semiconductor lasers.The index-coupled DFB laser usually introduce phase shift gratings for realized index-coupled mechanism,and the fabrication process requires re-growth epistaxial technology.The cost of the fabrication process is high,and due to its structural properties,The index-coupled DFB lasers are difficult to achieve wide tunable lasers.Traditional gain-coupled DFB lasers need introduce periodic absorption for realizing single-longitudinal mode ouput,However,They are still depend on preparation technology and secondary epitaxy technique.At the same time,The introduced periodic absorption reduce the output power of gain-coupled DFB lasers and other important performance parameters such as electro-optic conversion efficiency,The traditional gain-coupled DFB laser are lack of commercial attributes.In this paper,First time,780 nm and 905 nm tunable DFB semiconductor lasers based on the structure of the surface grooves are fabricated successfully by I-line lithography technology.The tunable DFB lasers achieved super wide tuning range and single-longitudinal mode ouput.The lasers in this paper have broaden the definition of tuning range for DFB lasers.The process of fabrication is relatively simple and it needn't to introduce re-growth technique,The DFB lasers can realize the mass production and the lasers have great market potential.(1)The theory of semiconductor laser is briefly expounded,the optical waveguide mechanism of single-longitudinal mode DFB semiconductor laser is modeled and analyzed by using the theory of transmission matrix to realize the surface isolation grooves,and the conclusions are theoretically supported for the design of the coupled optical waveguides of DFB semiconductor lasers in this paper.The theory of semiconductor laser is described in this paper,and the mechanism that how to realizing single-longitudinal mode is modeled and analyzed by using the theory of transmission matrix,and the conclusion provides theoretical support for the Distributed Feedback Bragg Semiconductor Laser Based on Surface Isolation Grooves Structure.(2)Design 780 nm tunable DFB semiconductor lasers based on the surface of the isolation grooves structure whose cavity length is 1 mm,peak wavelength is about 780 nm.Both facets of the device cleavage was coated optical thin-films,the transmission rate was 95% and 5% respectively.The tunable DFB semiconductor lasers realize stable single-mode laser phenomenon and high tunability when the operating temperature is at room temperature,the laser output power is up to 148.2 mW,the slope efficiency is about 0.28 mA/mW,the Side-Mode Suppression Ratio is up to36.25 d B,when the injection currents are between 90 mA and 400 mA,operating temperature within the range of 10 ? to 45 ?,the tuning range of the laser is up to17.5 nm.(3)Design and fabricated a tunable DFB semiconductor lasers based on surface grooves structure,whose cavity length is 1 micron,lasing wavelength near 905 nm,the threshold is about 85 mA at room temperature.The uncoated tunable DFB semiconductor laser's output power is up to 145.3 mW,the slope efficiency is 0.28 mA/mW,conversion efficiency was over 27%.The uncoated DFB semiconductor laser Side-Mode Suppression Ratio is up to 37 d B,and the device's 3 db line width was about 23 nm.With the increase of temperature and injection current,the red-shift is stable.(4)Design and fabricated a four-channel tunable DFB semiconductor laser array based on surface grooves structure,whose peak wavelength is round 905 nm,and the cavity length were 1 microns.Different channel versus different surface isolation grooves structure and it results in different lasing wavelengths.Each uncoated channel DFB semiconductor laser's out power was about 100 mW,and the peak wavelength red-shift phenomenon was stable,single channel of tunable range for 19 nm.Side-Mode Suppression Ratio of one uncoated channel was up to 44.25 d B,the four-channel array is in the injection current between 130 mA and 400 mA,the wavelengths tuning range is up to 48 nm at 10 ? and 45 ? temperature range,The photolithography processes of tunable DFB semiconductor lasers mentioned in this paper adopt I-line photolithography technology and related preparation.The fabrication processes were relatively simple,the processes tolerance space is large,the experimental results can be reproduced,the processes are highly controllable,and the mass production can be realized.The performance parameters of tunable DFB semiconductor laser designed and fabricated in this paper can meet the needs of industrial requirement with relatively low cost and short production cycle.It has great commercial value for industry and there are prospects in the fields of atomic clock,li DAR,optical integration,space optical communication and spectral detection.