Pressure tuning of high-power laser diodes

We demonstrate wide-range wavelength tunability of high-power laser diodes emitting at 660 nm, 808 nm, and 980 nm. Pressure shifts of the emission wavelength are due to the increase of bandgaps of III-V semiconductors under pressure with the rate of about 10 meV per kbar. For the 980 nm InGaAs/GaAs laser the threshold currents and the quantum efficiencies remain constant with pressure which allows for the constant operating current and the emitted power in the full tuning range. For 808 nm GaAs/AlGaAs and 660 nm InGaP/AlGaInP lasers there is an increase of threshold currents with pressure related to the direct-indirect crossover in the conduction band of AlGaAs and AlGaInP. This limits the tuning range unless we operate the laser at lower temperature. We designed the pressure cell with Peltier cooling allowing for independent control of temperature down to 0 Celsius and pressure up to 20 kbar. This device allows for the tuning of 980 nm laser down to 840 nm, 808 run laser down to 720 nm, 660 nm laser down to 620 nm.