Second-harmonic generation from thermally-poled twin-hole silica-glass optical fiber and enhancement by quasi phase matching

• Published in: Thin solid films 2008-07, Vol.516 (17), p.5890-5893
• Main Authors: Mizunami, Toru, Sadakane, Yasukazu, Tatsumoto, Yuhei
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Fiber optics; Frequency conversion; harmonic generation, including high-order harmonic generation; Fundamental areas of phenomenology (including applications); Germanosilicate glass; Nonlinear optics; Optical fiber; Optics; Physics; Poling; Quasi phase matching; Second-harmonic generation; Second-order nonlinearity; Silica glass; Space charge layer
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2007.10.030

The second-harmonic generation from optical fibers was studied using a twin-hole fiber. Metal wire electrodes were inserted into the holes of 35 μm ϕ, and the poling voltage was applied to a 20-μm-thick layer including the germanosilicate core. Q-switched Nd:YAG laser pulses were coupled to the core of the fiber, and the second-harmonic wave was measured with a photomultiplier. The quasi phase matching was performed by periodic erasure of nonlinearity. The poled fiber was irradiated with a KrF excimer laser through a silica mask patterned with a 40-μm pitch chromium stripe. By changing the angle of the fiber with respect to the mask pattern the optimum period was found to be 41.1 μm, then the second-harmonic power increased by a factor of up to 15. Mechanisms of thermal poling and ultraviolet depoling were discussed.