Mode control in VCSELs using patterned dielectric anti-phase filters

Anti-phase reflection;Dielectric filter;Mode control;Single mode;Vertical-cavity surface-emitting laser (VCSEL)

Kesler, Benjamin A

关键词: Anti-phase reflection;    Dielectric filter;    Mode control;    Single mode;    Vertical-cavity surface-emitting laser (VCSEL);   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/97656/KESLER-DISSERTATION-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

A novel transverse mode control method to achieve single-fundamental-mode lasing and higher-order-mode suppression using a multi-layer, patterned, dielectric anti-phase (DAP) filter is employed on the top of oxide-confined and proton-implanted vertical-cavity surface-emitting lasers (VCSELs). Dielectric layers are deposited and patterned on individual VCSELs in a wafer-scale process to modify (increase/decrease) the mirror reflectivity across the oxide aperture via anti-phase reflections, creating spatially-dependent threshold material gain and VCSEL lasing mode control. A one-dimensional (1D) plane-wave propagation method is used to calculate the dielectric layer thicknesses in each spatial region needed to facilitate or suppress lasing. A Quasi-3D oxide-confined VCSEL model is formulated using a combination of variations of the propagation matrix method, the weighted effective index method, and the step-index fiber mode dispersion (BV) curves to properly calculate the effect of the DAP filter on the calculated cavity modes as well as determine the optimal radial proportions of the filter. A single-fundamental-mode, continuous-wave output power greater than 4.0 mW is achieved on an oxide-confined VCSEL at a lasing wavelength of 850 nm with a side-mode suppression ratio (SMSR) greater than 25 dBm. Proton-implanted VCSELs achieve a single-fundamental-mode, continuous-wave output power of up to 3.5 mW with a SMSR of 25 dBm. The behavior of the proton-implanted devices both with and without the DAP filter illuminates an unobserved annular thermal guiding mechanism even in smaller device sizes, contrary to historical models which have calculated or assumed a parabolic refractive index or gain-guided profile. A finite difference, self-consistent thermal, electrical, and optical model is developed and agrees well with the observed results both with and without the DAP filter. The dielectric anti-phase filter is an additive, non-destructive method that allows for mode selection at any lasing wavelength and for any VCSEL layer structure or design without the need for destructive etching techniques or epitaxial regrowth. It also offers the capability of a tailored filter design based on available materials and deposition methods.