Study On 770 Nm And 795 Nm Gain-coupled DFB Semiconductor Lasers Based On Surface Periodic Electrical Injection

With the rapid development of 5G communications,big data,cloud computing,Internet of Things,etc.,semiconductor lasers with the advantages of long service life,low cost,small size,light weight,high reliability,and low power consumption have been widely used.Especially the distributed feedback(DFB)semiconductor laser with high stability,good single-frequency characteristics,narrow line width and tunable wavelength.On the basis of Fabry-Perot(FP)lasers,periodic refractive index perturbation is introduced to periodically modulate the real part(index coupling type)or imaginary part(gain coupling type)of the refractive index to adjust longitudinal mode lasing mode,this is the DFB semiconductor laser.Index-coupled DFB semiconductor lasers have inherent dual-mode lasing problems,which need to be resolved by introducing additional 1/4 wavelength phase shift gratings to achieve single longitudinal mode lasing.In addition,a high-quality cavity coated needs to be evaporated to solve the mode crosstalk problem caused by natural cleavage,and precision techniques such as secondary epitaxial growth are also required.Although the traditional gain-coupled DFB laser can also obtain single longitudinal mode lasing,it still requires precision techniques such as secondary epitaxy and nano-scale grating preparation.In this paper,i-line lithography technology is used to fabricate gain-coupled DFB semiconductor lasers,which do not require precision technologies such as secondary epitaxy and nano-size gratings.The cost is greatly reduced,and the single-mode tunable range of the fabricated device is generally more The DFB laser is several times larger.This thesis mainly studies the structure design,device preparation,and structure analysis of gain-coupled DFB semiconductor lasers.The specific research contents and results are as follows;(1)The optical characteristics of the waveguide structure of the surface high-order grating DFB semiconductor laser are analyzed using the transmission matrix and coupled wave theory method.Combined with the simulation calculation of PICS3 D,COMSOL Multiphysics and other software,it provides a solid theoretical basis for the design and optimization of device structural parameters.(2)Using the surface high-order grating,the single longitudinal mode lasing near770 nm of the Al Ga As double quantum well gain coupled DFB semiconductor laser is realized.Using surface grating technology and i-line lithography technology,without using expensive secondary epitaxy and nano-scale lithography technology,the cost is low.Using periodic current injection technology,a gain coupling mechanism is formed,and a DFB laser with a lasing wavelength near 770 nm is obtained.After the device is cleaved into bar strips,a high-reflection film and an antireflection film(HR>99%,AR<0.5%)are respectively plated,and then cleaved into a single-tube device.Through the test at 20℃,the maximum output power of our device can reach 116.8 m W,the maximum SMSR can reach 36 d B,and the 3d B line width is 0.26 pm(128 MHz).(3)Without etching the grating,using surface periodic injection current technology,an Al In Ga As single quantum well gain-coupled DFB device with a lasing wavelength of 770 nm was fabricated,with a maximum output power of 116.3 m W,a maximum SMSR of 33 d B,and the 3d B line width is 1.78 pm.(4)Using surface periodic current injection technology,the single longitudinal mode lasing at 795 nm of the Al In Ga As double quantum well gain coupled DFB semiconductor laser is realized.Using periodic surface grating technology and i-line lithography technology,a gain coupling mechanism is formed,and expensive secondary epitaxy and nano-level lithography technologies are not used,and the cost is low.At 20 ℃,the maximum output power of the device is 50.89 m W,and the maximum side mode suppression ratio is 34.56 d B.And the single-mode tunable range of the device is large,and the tuning range reaches 12.792 nm.The slope of wavelength change with temperature is 0.401 nm/℃(generally the slope of DFB laser is less than 0.1 nm/℃),which is equivalent to FP laser,that is,the device has the single-mode lasing performance of DFB laser and the unit temperature width of FP laser tuning performance.