Design of a surface-emitting, subwavelength metal-clad disk laser in the visible spectrum

Abstract

We analyze metal-clad disk cavities designed for nanolasers in the visible red spectrum with subwavelength device size and mode volume. Metal cladding suppresses radiation loss and supports low order modes with room temperature Q of 200 to 300. Non-degenerate single-mode operation with enhanced spontaneous emission coupling factor β is expected with the TE 011 mode that has a 0.46(λ 0 /n) 3 mode volume and Q = 210 in a device of size 0.12λ 3 0 . Threshold gain calculations show that room temperature lasing is possible using multiple GaInP/AlGaInP quantum wells as the gain medium. Placing a planar metal reflector under the cavity can enhance radiation and extraction efficiencies or increase the Q, without incurring additional metallic absorption loss. We show that the far-field radiation characteristics are strongly affected by the devices' immediate surroundings, such as changes in metal cladding thickness, even as the resonant mode profile, frequency, and Q remain the same. When the metal cladding is 1 µm thick, light radiates upward with a distinct intensity maximum at 45 • ; when the cladding is 100 nm thick, the emitted light spreads in a near-horizontal direction. Karouta, Y.-S. Oei, R. N otzel, C.-Z. Ning, and M. K. Smit, "Lasing in metal-insulator-metal sub-wavelength plasmonic waveguides," Opt.

Plasmonic distributed feedback lasers at telecommunications wavelengths

“…Reducing the grating periods on one side of the quarter wavelength shift would allow for out coupling of some light into a waveguide. However, with the base threshold gain being ~1200 cm 1 at room temperature, there is likely only potential for extraction of a few tens percent of the light in the cavity [9,10].…”

“…Most devices are optically pumped and use dye or semiconductor gain medium, however some semiconductor devices are electrically pumped, which brings them closer to applications. Furthermore, there has also been work looking at the theory behind such devices [9,10], showing that some designs have the potential for useful devices.…”

Metallic subwavelength-cavity semiconductor nanolasers

“…Theoretical studies 3,[41][42][43][44][45] have predicted many appealing features of metallic nanolasers such as small volume, high density integration and good thermal dissipation. Such small lasers potentially can operate at high modulation speed.…”

Surface-Emitting Metal Nanocavity Lasers

“…Considering that semiconductor gains can reach several thousands per centimeter, there is room to make devices where a large proportion of the lasing mode energy is coupled out. Others have also indicated that for both lasers and LEDs, such pillar structures can in theory have quite acceptable efficiencies, in the order of 50% [16,21]. For the propagating mode devices, controllable out coupling is achieved by adjusting the transmission characteristic of one of the mirrors, which with a metal mirror means controlling its thickness [17].…”

“…However, the light exiting the cavity will in principle have to pass through some subwavelength aperture, which can lead to the light emitted over a wide solid angle. Some simulation studies have been done of these emission properties [21]. In many applications, a low divergence beam would be desired.…”