Effect of Phase-Shifter Domains in Quasi-Phase Matching Devices

Abstract

With the inception of Quasi-Phase Matching (QPM) technique, there has been a wide interest by the researchers to utilize the concept of domain engineered superlattices structures in optical networking. We present a theoretical approach to study the effect of phase-shifter (PS) domains in engineered optical superlattice structures and analyze the second harmonic spectral response. QPM device with PSs is the easiest approach to generate multiple and tunable second harmonic spectrum to utilize the same in optical communication system. IntroductionThe development of Quasi-Phase Matching (QPM) technique is significantly important due to the advantages of the process non-linear optical frequency conversion or mixing. This approach has been successfully acquired in ferroelectric crystal such as lithium niobate (LiNbO 3 ), lithium tantalate (LiTaO 3 ) etc., by various methods of domain reversals like electric field poling, caliographic poling and UV irradiation. Using the electric field poling method, various domain structures of QPM has been fabricated for desired applications. The engineered domain structures of QPM are designed to compensate the mismatch among the wave vectors of the interactive waves which is concluded in generating higher harmonics. In this operation, the non-linear optical coefficient (d eff ) of the ferroelectric crystal is polarized periodically or aperiodically by applying high electric field resulting into a grating structure of period Λ = 2l c , where l c is the coherence length and L is the

Engineering phase shifter domains for multiple QPM using simulated annealing algorithm

“…Figure 3(a) shows the dual peak SHG spectrum with a device length of 0.8 cm containing 1000 domains in its length. With the SA algorithm, the position of the phase shifter was identified as the 500 th domain [22]. For the triple peak SHG spectrum, the position of the phase shifters was identified as 419 and 631.…”