Vertical Cavity Surface Emitting Laser Which Is Used To Produce Terahertz (THZ)

Vertical cavity surface emitting laser(Vertical-Cavity Surface-Emitting Laser,referred to as VCSEL)has many advantages compared with edge emitting laser: easy to be integrated monolithicly on two-dimensional,low threshold current,operationing under dynamic single mode can maintain a high degree of stability,high frequency modulation bandwidth and low manufacturing cost.With these advantages,the vertical cavity surface emitting lasers has received widespread attention from the beginning,and rapidly applied in the fields of optical communication,laser printing and photonic computer,therefore has attracted more and more researchers and research institutions all over the world..In the process of VCSELs' development,the wave of terahertz frequency range were few touched,from the side of wavelength,terahertz is between millimeter wave and infrared spectrum,that range is quite wide,occupying a special position in the electromagnetic spectrum,in the transition area from electronics to photonics.Because of the lack of effective methods of radiation generation and detection,the electromagnetic wave in this band has not been fully studied and utilized.In the range of terahertz and microwave,laser research is also relatively few,the lack of the method that effectively generating and detecting terahertz wave,called “THz Gap”,which is the last frequency window to conduct a comprehensive and in-depth study of the spectrum.The generation of THz wave is the key to the development of THz science and technology.In the existing THz wave radiation source technology,the method of using electronic method to extend the frequency of electromagnetic radiation to high frequency can produce high power THz wave,but the frequency is low,generally below 1THz.The other method is extending the laser frequency to the low frequency by using the photonic method can produce the THz wave with good directivity and coherence,but the output power is low.At present,the main problem is the lack of method to produce THz radiation which contains the characteristic that high power,high energy,broadband tunably,low-cost,portable,and stable operation at room temperature.We think up of an idea that change the length of resonant cavity of vertical cavity surface emitting laser to produce multi longitudinal mode,from which select two longitudinal modes,if their frequency difference is in the range of terahertz frequency,then the two lasing wave can produce terahertz wave by the way of difference frequency.The main contents of this paper are summarized as follows: 1.Calculation of the reflection spectrum of DBR starting from the transfer matrix,and analyzed the influence factors of DBR reflection spectrum,using MATLABto simulate and analysis the overall transmission spectrum of VCSEL devices with different pairs of DBR,based on that,analysised the transmission spectrum of the VCSELs that have inserted layer.At the same time,MATLAB is used to simulate the phase spectrum and the standing wave spectrum of the VCSEL.2.On the basis of the structure of IQE 980 nm VCSEDL,inserting Al Ga As with different aluminum components,different optical thickness in different positions.Simulating and analysising the characteristics.3.Based on the thickness of the inserted layer,the relationship between the frequency and the frequency difference of the inserted layer and the lasing wavelength,the lasing wavelength and the frequency difference is analyzed.4.Dual wavelength vertical cavity surface emitting lasers were fabricated by photolithography,selective corrosion and selective oxidation,and their I-V curves,P-I-V curves,spectra,and near field images were analyzed.The results show that there are a number of longitudinal modes in the near field image of the VCSEL with the insert layer.It also can be seen that there are many wavelengths in the spectral image.However,the difference of the two wavelength intensity of the devices with different sizes of the Oxidized aperture differs greatly.