| Vertical cavity surface emitting laser(VCSEL) is widely used in the fields of optical communication and optical interconnection due to its small size,low threshold current,single longitudinal mode operation and easy integration,etc.At this stage,with the application of the 3D recognition function of the mobile phone camera,the 940 nm VCSEL,as an ideal light source,has received more and more attention in the field of electronic consumer.For the VCSEL device structure,people have done a lot of research in theory and experiment at this stage,but most of their research is directed to lasers used in the field of optical communication.In the field of electronic consumer,there is still little research on the structure optimization design of 940 nm VCSEL.With the rapid development of 5G and the Internet,the data traffic brought about by explosive growth,people have put forward higher requirements for 940 nm VCSEL devices used for 3D recognition of mobile phones.Battery energy consumption,beam quality and eye safety are main issues that need to be paid attention to in daily applications such as mobile phones and other electronic devices.These problem are closely related to the threshold current and beam quality of VCSEL.Therefore,improving the photoelectric characteristics and optical mode of VCSELs is currently the main research work.This paper mainly studies the relationship between the photoelectric characteristics and optical mode selectivity of the 940 nm vertical cavity surface emitting laser with mode filter and half-wavelength cavity for 3D recognition and the structural parameters of the device.Not only the threshold current and the optical confinement factor of the vertical cavity surface emitting laser under two cavity lengths are investigated,but also the influence of the thickness and the diameter of the mode filter on the output of the fundamental transverse mode.According to different structural parameters,the calculated threshold current,output power,light field distribution,reflectivity,etc.are analyzed and compared,and an optimal device structural parameter is finally obtained to make it more meet the requirements of practical applications.The specific research content and results are as follows:(1)The threshold current of VCSEL devices with resonator lengths of?/2 and X is studied.The results show that compared with the VCSEL with the cavity length ?,the threshold current corresponding to the cavity length ?/2 is reduced by 30.8%,and the output power is increased by 14.3%.(2)When the cavity length is ?/2 and ?,the optical field distribution along the cavity length direction in the active region is studied.When the cavity length is ?/2,the peak value of the optical intensity in the center of peak of the active region is higher than that of the adjacent peaks on both sides;when the cavity length is ?,the peak value of the optical intensity in the center peak of the active region is lower than that of the adjacent peaks on both sides.The calculation results show that the optical confinement factors corresponding to the two cavity lengths are 3.44%and 3.01%,respectively.Compared with the ? cavity VCSEL,the ?/2 cavity VCSEL has an increased optical confinement factor of 12.5%.(3)The influence of the thickness and etched diameter of the mode filter on the output of the fundamental transverse mode is studied.The mode filter realizes mode control by increasing the mirror loss of higher-order transverse modes.When the thickness of the filter increases from 10 nm to 160 nm,the reflectivity of all transverse mode on the p-type DBR first decreases and then increases,and it is the minimum value at 80 nm,so the filter thickness is optimized to 80 nm.When the diameter of the filter is increased from 0.5 ?m to 5.5 ?m,the difference between the reflectance of the fundamental transverse mode and higher-order transverse mode on the p-type DBR increases first and then decreases.The maximum value is obtained when the diameter is 2.5 ?m.So,the optimized diameter of the filter is 2.5 ?m. |
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