Continuous-wave operation of 1550 nm low-threshold triple-lattice photonic-crystal surface-emitting lasers

Abstract

Benefitting from narrow beam divergence, photonic crystal surface-emitting lasers are expected to play an essential role in the ever-growing fields of optical communication and light detection and ranging. Lasers operating with 1.55 μm wavelengths have attracted particular attention due to their minimum fiber loss and high eye-safe threshold. However, high interband absorption significantly decreases their performance at this 1.55 μm wavelength. Therefore, stronger optical feedback is needed to reduce their threshold and thus improve the output power. Toward this goal, photonic-crystal resonators with deep holes and high dielectric contrast are often used. Nevertheless, the relevant techniques for high-contrast photonic crystals inevitably complicate fabrication and reduce the final yield. In this paper, we demonstrate the first continuous-wave operation of 1.55 μm photonic-crystal surface-emitting lasers by using a ‘triple-lattice photonic-crystal resonator’, which superimposes three lattice point groups to increase the strength of in-plane optical feedback. Using this geometry, the in-plane 180° coupling can be enhanced threefold compared to the normal single-lattice structure. Detailed theoretical and experimental investigations demonstrate the much lower threshold current density of this structure compared to ‘single-lattice’ and ‘double-lattice’ photonic-crystal resonators, verifying our design principles. Our findings provide a new strategy for photonic crystal laser miniaturization, which is crucial for realizing their use in future high-speed applications.

High-power, stable single-mode CW operation of 1550 nm wavelength InP-based photonic-crystal surface-emitting lasers

“…By employing the double-lattice PC structure in GaAs-based PCSELs operating at wavelengths in the range of 900-1000 nm, [8][9][10][11][12][13] CW singlemode lasing with large emission areas up to a 3 mm diameter has been demonstrated, with an output power of up to 50 W with a narrowly diverging beam. 10) PCSELs operating at various other wavelengths have been also reported using different material systems including GaN-based PCSELs (400-550 nm), 14,15) InP-based PCSELs (1300-1600 nm), [16][17][18][19][20] as well as far-infrared (terahertz) quantum cascade PCSELs. 21) Among these wavelengths, 1550 nm is particularly important for fiber-based optical communications for the purpose of minimizing transmission loss.…”