We demonstrate efficient wavelength tuning by means of hydrostatic pressure of an InGaN/GaN laser diode grown on bulk GaN crystal. Energy shifts of the emitted light with pressure have been found to be about 36 meV/GPa, which are high magnitudes for nitride-based device structures. This result is interpreted as being indicative of efficient screening of built-in electric fields in the studied device. Furthermore, the threshold current of the laser diode was found to be independent of applied pressure. The high magnitude of the pressure coefficient allowed for the achievement of a laser tuning range of up to 10 nm in the blue/violet region, using compact pressure equipment.

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Photoluminescence (PL) from GaAs quantum wells with widths from 50 to 300 A and AI,Ga,.,As barriers ( x = 0.3 and 1) was studied under pressure up to 35 kbar at two temperatures (300 K and 77 K). We used (and compared) three types of pressure devices: gas cells, liquid cells and the diamond-anvil cell. Accurate values for the pressure variation of the PL energy were obtained. They reveal the small dependence on the parameters of the well, in agreement with the envelope-function calculation. Pressure shift of the PL lines is the same at 77 K and at 300 K. In several samples we found the change of the pressure coefficient of the direct (r) line at the T-X crossover pressure. We interpret this as the resonance effect due to the mixing of the r state in t h e well with the X continuum in the barriers. This means that the pressure dependence of the quantum-well pressure. From our results we obtain the linear pressure coefficient of the GaAs energy gap equal to 11.6 meV kbar-'. The deformation potential of the gap seems to be almost independent of pressure u p to 15 kbar. shouIci noi be iiiied Wiih a singie Cur".e 'irelow and above ihe r-x CiosBOvei

In Ga As Sb ∕ Al Ga As Sb type-I midinfrared diode lasers emitting continuous wave at 2.4μm at room temperature have been studied under high hydrostatic pressure. When the pressure was increased up to 19kbar, the threshold current varied from 240to400A∕cm2, showing a minimum of 200A∕cm2 close to 8kbar, and the emission spectra shifted to shorter wavelengths by up to 700nm (i.e., from 2.4μmto1.7μm). This exceptional tuning range could be very useful in tunable diode laser absorption spectroscopy.

Optical transitions between quantum well subbands have large oscillator strengths and narrow linewidths so that they can be used for the detection of infrared light. Here we show that the intersubband separation can be varied over a wide energy range by depositing a thin barrier layer of AlGaAs in the middle of a GaAs well. In a sufficiently narrow well it should be possible to push the subbands out of the well, i.e., perform the transition from the quasi-two-dimensional case to the quasi-three-dimensional case.

Photocurrent spectroscopy and hydrostatic-pressure-dependent electroluminescence are used to show that heavy 1×1019cm−3 Si doping of quantum barriers is sufficient to achieve full screening of polarization-induced electric fields (PIEFs) in nitride light emitting diodes (LEDs) and laser diodes (LDs) with InGaN quantum wells. Furthermore, it is shown that at currents close to lasing threshold in nitride LDs injected charge alone is sufficient to achieve full screening of PIEFs. In contrast, full screening at low currents can only be accomplished via Si doping of quantum barriers.

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The emission wavelength of broad-area AlGaInP/InGaP quantum-well lasers is tuned by the application of high hydrostatic pressure and low temperature from 645 down to 575 nm, i.e., from the red through the orange to yellow spectral range. Emission powers up to 300 mW are obtained in the full tuning range. The pressure and temperature dependence of threshold currents indicates that leakage occurs into the L and X minima in the barriers.