Very-low-threshold photonic band-edge lasers from free-standing triangular photonic crystal slabs

Photonic band-edge lasers are realized in the free-standing triangular photonic crystal slab with InGaAsP quantum wells at 80 K. Surface-emitting lasing actions are observed from the samples whose wavelengths correspond to the second or the third photonic band edge near the Γ point of the band structure, which is confirmed by the three-dimensional finite-different time-domain calculation. A very low threshold of 35 μW (incident pump power) is achieved from the laser operating near the third transverse-electric-mode band edge. This low threshold is benefited from low optical losses near the Γ point as well as reduced surface recombination carrier losses and enhanced material gain at low temperature. It is interesting to note that this two-dimensional distributed feedback lasing action is observed from a surprisingly small pump area of 6 μm in diameter.