Gain spectra in GaAs double−heterostructure injection lasers

Abstract

Gain spectra for GaAs double−heterostructure junction lasers have been obtained with high resolution. This is accomplished by using an automated data aquisition system to analyze the Fabry−Perot resonance modulation in the spontaneous emission spectra. For active regions doped with Ge at a level of 4×1017 cm−3, the gain in the TE polarization at a fixed wavelength increases linearly with current, below lasing threshold. However, the peak gain (at a variable wavelength) increases slightly faster than linearly with current. The photon energy at which gain is a maximum increases logarithmically with current. Gain in the TM polarization depicts the same general behavior as that for the TE case, except that it is slightly less than the TE gain. It is concluded that for this particular doping the spectral gain characteristics are intermediate between those for undoped and heavily doped active regions. Above the threshold for lasing in the TE mode the TE gain spectra are well saturated, with new fine details revealed in the saturated spectra. On the other hand, gain in the nonlasing TM polarization is not well saturated above threshold, with marked differences in gain between high and low photon energies relative to the TE lasing energy.

Optical gain measurements based on fundamental properties and comparison with many-body theory

“…The gain is then calculated using the HakkiPaoli method, in which the ratio of intensity maxima and minima of the Fabry-Perot modes is related to the gain. 1 As mentioned earlier, this technique relies on a good signal to noise ratio, which may be insufficient for wavelengths near the band edge where the ASE intensity is extremely low. In the peak gain region for currents near threshold, the modes are almost lasing and may not be completely resolved by the spectrometer.…”

Effects of the current distribution on the characteristics of the semiconductor laser with a channeled-substrate planar structure

“…This linear gain-current assumption is based on theoretical and experimental results [9,10). An experimental setup for this measurement is shown in It is also Interesting to note that the profile tailed off more slowly on one side than the other.…”

GaAs Quantum Cascade Lasers: Fundamentals and Performance

“…where J is the current density and g(λ) the gain coefficient as a function of the wavelength) is extracted from the fringe contrast using numerical Fourier analysis of the subthreshold spectra in a modified version of the Hakki-Paoli technique [24]. In Figure 5 the peak net modal gain (= J g(λ peak )Γ AR − α W ) is plotted versus drive current density.…”