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Efficient power extraction in surface-emitting semiconductor lasers using graded photonic heterostructures

AGD-2: Efficient optical power extraction is a challenge for any semiconductor laser, and particularly for surface-emitting lasers with photonic crystal resonators. Drawing inspiration from the spatial wavefunction profiles in type-II semiconductor quantum wells, we demonstrated a generic technique to improve output efficiency by spatially separating the optical modes in the laser cavity, and selectively dampening the less efficient ones. Experimental work was underpinned by theoretical analysis, and was collaborative with Paris South, Lyon, and Cambridge (part-funded through French national grant, ‘Hi-Teq’, and our ERC Advanced Grants ‘NOTES’ and ‘TOSCA’). Record power, low-divergence, single-mode surface-emission was demonstrated in terahertz cascade lasers.