Major features of frequency sweeping of emission from heterojunction quantum lasers |
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Authors: | B F Kuntsevich V K Kononenko |
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Institution: | (1) B. I. Stepanov Institute of Physics, National Academy of Belarus, 68 prosp. Nezavisimosti, Minsk, 220072 |
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Abstract: | We have used numerical modeling to establish the major features of the variation (sweeping) of the “ instantaneous” laser
frequency of heterojunction quantum lasers as a function of the pump current modulation frequency and tuning of the lasing
frequency within the gain band. The active medium is described within a two-band model with identical distribution of levels
for the electron and hole subbands, assuming transitions with no selection rule between the ground-state subbands. Sweeping
of the laser frequency occurs due to variation of the refractive index of the active medium, as a result of the variation
in the concentration of nonequilibrium charge carriers. Laser frequency sweeping does not occur for low current modulation
frequencies, corresponding to realization of the quasisteady-state lasing regime. In the other limiting case of relatively
high current modulation frequencies, the modulation depth of the laser output also tends toward zero. The magnitude of the
sweep is greatest in the intermediate current modulation frequency region. For a specified current modulation frequency, the
dynamic shift of the laser mode depends on the position of the lasing frequency within the gain band.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 223–229, March–April, 2007. |
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Keywords: | heterojunction quantum laser pump current modulation dynamic shift of the laser frequency (sweeping) |
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