GENERATION OF OPTICAL PULSES FROM A PHASE-MODULATED WAVE AMPLIFIED IN A CYLINDRICAL WAVEGUIDE BY A TRAVELING SPACE CHARGE WAVE
A. S. Abramov1, I. O. Zolotovskii1, V. A. Lapin1, S. G. Moiseev1,2, D. G. Sannikov1
1Ulyanovsk State University, Ulyanovsk, Russia
2Kotelnikov Institute of Radioengineering and Electronics, Ulyanovsk Branch, Russian Academy of Sciences, Ulyanovsk, Russia
Keywords: semiconductor waveguide, space charge wave, phase modulation, ultrashort pulse generation
Abstract
In this study, we consider the dynamics of interaction of near-IR electromagnetic radiation with a space charge wave (SCW) propagating in the volume of a cylindrical n - GaAs waveguide. A possibility of phase modulation of a slow electromagnetic wave (like the whispering gallery mode) with a depth of 10 to 30 radians is demonstrated. It is found that the phase-modulated radiation splits into a sequence of ultrashort pulses during further propagation in the optical waveguide. The repetition rate of the formed pulses coincides with the frequency of the SCW realized in the waveguide. The peak power of the generated pulses exceeds the average power of the radiation introduced into the waveguide approximately by three orders of magnitude and can reach values of 20-50 W. The numerical analysis shows that the optimal length at which optical pulses are formed outside the waveguide depends on the amplitude and frequency of the modulation of the concentration of free charge carriers associated with the propagating SCW.
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