Wavelength tuning of laser diodes using hydrostatic pressure

Direct bandgap of most III-V semiconductors (AIGaAs, InGaAs, InGaP, InAs) increases with hydrostatic pressure at the rate of about 10 meV per kbar. Thus the emission wavelength of semiconductor lasers shifts to the blue under the application of high pressure. We demonstrate that this effect can be used for wavelength tuning of laser diodes in a very wide spectral range. Using the specially.. designed liquid pressure cell working up to 20 kbar the 1550 nm laser was tuned down to 1270 nm, the 1300 run laser was tuned down to 1100 nm, and the 980 nm laser was tuned down to 840 nn. The emitted light passes through the sapphire window or through the fiber directly coupled to the laser. The threshold current and the quantum efficiency for the 980 nm laser remained constant with pressure, for the two other lasers the thresholds decreased with pressure. Thus we obtained the constant emission power in the full tuning range. We hope that this compact device will find applications as a tool for characterization of some optical network devices or parts of optical transmission lines.