Magnetic field dependence of second harmonic generation, coherence lengths, and second order susceptibilities near the band edge in InSb

Abstract

Resonant effects in second harmonic generation (shg) in InSb near the energy gap have been studied by radiating with a high power Q-switched CO2 laser at 10.6 mu m and tuning the energy gap by applying magnetic fields up to 55 kG in samples of carrier concentrations from 8*1014 to 5*1016 cm-3 at a temperature of 12 K. Absolute, independent measurements of the coherence lengths lc+- were made as a function of magnetic field, using circularly polarized radiation and wedge shaped samples, by a modification of the original 'Maker' experiment. These results, together with measurements of SHG +- and absorption coefficients alpha +- have yielded the magnetic field dependence of the second order nonlinear susceptibilities chi +- at 5.3 mu m. Virtual transition processes have been used to formulate the theory for the resonant behaviour of chi and lc and the effect of blocking by conduction band population is demonstrated experimentally.

On New Non-linear Magneto-optical Phenomena in Crystals and Liquids

“…As a particular case of magneto-electric frequency mixing (4) we have, at w 1 = w 2 = w and w 3 = k 3 = 0, second harmonic generation in a d .c . magnetic field [8,9] . At w 1 = w, k 1 = k and w 2 = w 3 = k 2 = k 3 = 0, the polarization (4) leads to the following second-order variation of the electric permittivity tensor D Eij(2)(w, k) = 4, TXij kleeem( -w,w,0,0, k)Ek(0)HI(0) (5) due to the simultaneous action of a d .c .…”

“…In particular, equipment is now available for the study of d .c . magnetic field-induced second-harmonic generation of laser beams [6,8,9] as well as for the observation of large enhancements in higher harmonics due to resonance at high magnetic fields [10,11], as in fact has been shown with regard to the third harmonic of CO 2 laser light in semiconductors [12] . Possibilities also exist for the observation of non-linear variations in magneto-optical rotation (Faraday effect) under the influence of laser light [13,14], and of other magneto-optical cross effects [15] .…”