Broadband second harmonic generation in a tapered isotropic semiconductor slab using total internal reflection quasi phase matching

Broadband second-harmonic generation in a double-tapered gallium arsenide slab using total internal reflection quasiphase matching

“…Fig. 2 shows the variation of the bounce lengths with respect to the number of bounces inside the slab corresponding to the fundamental centre wavelength of 9.146 m. As explained in our earlier work [11], the present scheme also corresponds mainly to non-resonant QPM since the interaction lengths between successive bounces cannot be optimized to be equal to an odd multiple of the coherence length for all the frequencies available in the input band of fundamental laser radiations. But a situation may arise wherein one length may coincide with an odd multiple of the coherence length of a particular frequency in the input band of fundamentals, whereas another length may coincide with an odd multiple of the coherence length of another frequency in the band and so may not give rise to resonant QPM scenario.…”

“…The expression for generated SH field after the first bounce inside the slab can be written as [6,11,13] E 2 (L 1 ) = JS 1 L 1 1 − e i2 1 2 1 where 2 1 = kL 1 , L 1 is given by Eq. (1), J = (16 2 ω 2 /n 2 1 c 2 )d eff (in cgs), S 1 is the fundamental beam intensity and d eff is the effective value of the d-coefficient corresponding to the slab material.…”

“…The value of d 14 is considered to be 107 pm/V for GaAs compound [11]. In the proposed scheme, since the angle of incidence changes at each reflection bounce, the effective dcoefficient (d ppp ) also undergoes change in its value at each reflection bounce.…”

“…This technique has been demonstrated in transparent (ZnSe) [9] as well as opaque [gallium phosphide (GaP)] [10] semiconductors and can indeed make the nonlinear optical technology accessible to a much wider range of potential users. Broadband SHG has also been theoretically reported in single-crystal tapered isotropic configuration (GaAs, ZnSe) using TIR-QPM technique [11]. Since a tapered slab has been considered, the length between successive bounces goes on increasing as the input collimated fundamental laser radiation propagates through the tapered slab, thereby ensuring the possibility of both non-resonant and resonant QPM.…”

Quasi-phase matched broadband difference frequency generation in the mid-infrared region using total internal reflection in a tapered gallium arsenide (GaAs) slab

“…A c c e p t e d M a n u s c r i p t converter is affected by optical beam walk-off which was absent in case of broadband SHG proposed by Saha et al using a similar configuration [24]. In a tapered slab, the interaction length between the successive bounces are all unequal which ensures the possibility of resonant as well as non-resonant QPM.…”