Qfactor improvement by capsule-shaped metallic cavity structure for subwavelength lasers

Abstract

A series of wavelength‐scale capsule‐shaped metallic cavity structures with InGaAs/InGaAsP multiple quantum wells are fabricated and characterized by photoluminescence measurement for the first time. By introducing cylindrical facets with optimal curvature to a conventional rectangular cavity, the electric field of the resonant mode is pushed effectively into the center of the mesa. As a result, the mode distribution at the metallic sidewalls and the plasmonic losses are reduced dramatically. We experimentally confirm up to fourfold enhancement in the Q factor of the fabricated capsule‐shaped cavity compared with that of a rectangular structure with same dimension. The measured results are consistent with the 3D finite‐difference time‐domain simulation, and validate the effectiveness of the scheme.

Waveguide-coupled metal-clad cavity with integrated feedback stub

“…3, similar to the ones reported in previous works. 20,26,29) The cavity has length L = 1.1 µm and width W = 0.84 µm. The bottom InP cladding is intentionally reduced to 250 nm to investigate the effect of Q-factor tuning more clearly.…”

“…Such capsule-shaped cavity is proved to reduce corner scattering and improve the optical confinement as compared to rectangular cavities of the same dimensions. 19,20) We first investigate the case where the cavity is evanescently coupled to SOI waveguide with outputs on both ends, as shown in Fig. 4(a).…”

“…[1][2][3][4][5][6][7] With the use of metallic cladding, optical mode can be confined tightly inside a wavelength-scale cavity, resulting in reduced footprint and energy consumption as well as enhanced lightmatter interaction through Purcell effect. 8) Various types of metal-clad lasers have been demonstrated experimentally by using cylindrical, [9][10][11][12][13][14][15] narrow waveguide, 16) rectangular, 17,18) and capsule-shaped 19,20) geometries. The first demonstration of electrically pumped wavelength-scale lasing under room temperature has been reported by using InP=InGaAs rectangular laser structure capped with metal.…”

Optimization and far-field characteristic of metal/dielectric coated circular semiconductor nano-lasers

“…Since then, significant progress has been made in this field. To further miniaturize the lasers and realize energy-efficient and integrable of the lasers, researchers have been exploring various shapes of metal-coated semiconductor microcavity lasers, including circular [2][3][4][5] , rectangular [6][7][8][9] , and capsule-shaped [10][11][12][13] cavities. Lasing has been successfully demonstrated under different conditions, such as continuous wave pumping, pulsed optical pumping at room temperature and so on.…”

Design and Analysis of Asymmetric Capsule-Shaped Metallic Cavities for Unidirectional Waveguide Coupling

“…Besides, optimizing the geometry of the cavity structure for a low-loss resonant mode can also increase the Q value effectively. For example, capsule-shaped cavity (CSC) structure [14][15][16] and Gaussian-shaped cavity (GSC) structure [17], which take advantage of Gaussian-like mode by introducing cylindrical facets to conventional metallic cavity, are proposed to confine the resonant mode tightly in the center of cavity with reduced metallic losses.…”