Study Of Antiguide Vertical Cavity Surface Emitting Laser And Its Two Dimensional Coherently Coupled Array

The vertical cavity surface emitting laser (VCSEL) is an attractive light sourcesince they have the characteristics of low cost manufacturing, low threshold, lowpower consumption, single longitudinal mode, high modulation bandwidth and easyfor array integration. Therefore, they have a high potential for various applications inoptical communication, short-distance optical interconnects and optical storage.However, in many high-end areas such as laser radar and medical testing, the VCSELshould have a stable single fundamental mode and a small beam divergence angleoutput, nearly diffraction-limited.The antiguide structure VCSEL can ensure the single mode operation in a largeraperture, having a better beam quality characteristic. Moreover, the antiguide structureVCSEL array exhibits a strong global leaky mode coherence feature. Thus possess abenefit of modal discrimination and stability. The in-phase mode output array is oneof the development trend of high-performance phase-locked VCSEL due to the neardiffraction-limited beam quality.The antiguide structure VCSEL and two-dimensional in-phase coherent arrayswere systematically studied in this dissertation supported by the Nation NaturalFoundation of China. The theoretical models, simulation, structure design, fabricationand testing techniques of cavity-induced antiguide VCSEL and proton implantedantiguide arrays were discussed. The main research works are as follows:1) The antiguide VCSEL theoretical model was established based on the basicVCSEL model, the effective index method and fiber mode theory. The thickness ofspacer layer was determined and resonance wavelength shift were analyzed. So thecavity induced index step can be calculated. The leaky mode loss of the antiguidestructure was analyzed and the lateral dimensions were designed using the accuratecylindrical transfer matrix method. Dielectric films Distributed Bragg Reflector (DBR)and the second epitaxy technology of MOCVD was also studied in order to fabricatethe device. At last, we have gotten a lasing output of0.28mW successfully bycreatively using the internal cavity contact method and the dielectric film.2) The principle of insulating layer formed by proton implantation was discussedcomprehensively. We demonstrate the key parameters of proton implantation VCSELsuch as the injection energy and dose. Secondary ion mass spectroscopy (SIMS)testing method was used to examine the process. The effects of proton implant energyon threshold and output power of vertical cavity surface emitting lasers were alsodiscussed. We make a thorough inquiry to the actual current injection aperture andoptimize the injection energy according to the actual structure. The output power andthreshold current obtained under the10μm aperture are1.7mW and4.3mA (Acta Physica Sinica, Vol61, No.21pp2142071-5), respectively. The proton implantationwas performed at a dose and energy of1E15/cm2and315kev, respectively.3) Two dimensional coherently coupled VCSEL array was fabricated usingproton implantation. The weak antiguide effect model was established to analysis theperformance of the array when consider the thermal effect and carrier injection. Weexplored the influence of inter-element on the device performance and solved thedifficulty of small aperture mask. A2×2array with the far field beamwidth of3.6degree, up to1.18×D.L.(diffraction-limited) and the output power of0.45mW wasachieved (IEEE Photonics Technology Letters, Vol26, No4,pp395-397）forcontinuous wave operation at room temperature. Compared to the reference solitaryVCSEL, it showed an excellent beam quality due to the in-phase coupling among theelements in the array.4) Since the traditional square frame electrode suffers ununiformity of currentinjection and the grid electrode suppress the in-phase mode, Indium-tin-oxide (ITO)current spreading layer was employed to improve the uniformity of the injectioncurrent when the array scale is become larger. We discussed the effect of variousthicknesses ITO layer on surface current spreading. A3×3in-phase coherentlycoupled array was achieved (IEEE Photonics Journal Vol.5, No.6, pp15026061-6).The far field divergence was lower to2.4degree and the output power up to4.3mW atpulse wave operation. While other research group employed bottom emitting designto achieve the in-phase coherently output. It is definitely a more complicated methodin larger scale proton implantation array.5) In order to exploring the influence of nearest number of the element on arraycoupling, a1×7array with hexagonal arrangement was performed. The in-phase andout-of-phase output mode was discussed theoretically and the near field images werealso obtained. Both of them are showed the unique characteristics of its specialarrangement.