Exploring a photonic quasi-crystal fiber for enhancing the efficiency of second harmonic generation: Modeling and analysis

Abstract

In this paper, we explore the possibility of using a new type of microstructured optical fiber called photonic quasi-crystal fiber (PQF) for enhancing the efficiency of second harmonic generation (SHG). We model a six-fold, index guided, silica core PQF with a relative air hole diameter ranging from 0.1–0.5. We compute the various factors related to SHG, namely, phase mismatch factor, wave-vector mismatch, coherence length, quasi-phase matching length and overlap area. Of the various factors, we focus more on the role of wave-vector mismatch and overlap area as these parameters are highly sensitive to the variations in the geometrical arrangement of air holes in the cladding. Further, these parameters are required to be as minimum as possible for enhancing the efficiency of SHG. We find that the wave-vector mismatch factor does decrease for higher values of pitch and for lower values of relative air hole diameter. However, the overlap area increases for higher values of pitch and for lower values of relative air hole diameter. Therefore, we optimize the hitherto mentioned parameters such that the wave-vector mismatch is 0.145μm−1 and the overlap area is 3.48μm2. With these values, we demonstrate a relative efficiency of 62.96%W−1cm−2 with the proposed PQF.