Pressure tuning of high-power laser diodes

Wide-range wavelength tunability is demonstrated for commercial high-power laser diodes emitting at 980 nm, 830 nm, and at 808 nm. High pressure shifts the emission wavelength of the lasers due to the increase of bandgaps in the active layers with the rate of about 10 meV per kbar. For the 980 nm InGaAs/GaAs laser the threshold currents and the differential efficiencies remain constant with pressure which allows for the constant operating current and the emitted power in the full tuning range. For 830 nm and 808 nm GaAs/AlGaAs lasers there is an increase of threshold currents with pressure related to the leakage through X minima in the conduction band of AlGaAs. 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. The laser beam passes through the sapphire window or through the multi-mode fiber. Our device allows for the tuning of 980 nm laser down to 840 nm, 830 nm laser down to 745 nm, and 808 nm laser down to 720 nm. We were able to keep the output power fixed in the full tuning range: 300 mW for the 980 nm laser and 400 mW for the 830 nm and 808 nm lasers.