Abstract

Periodic thermal poling of fibers is a promising technique for efficient quasi-phase-matched second-harmonic generation.¹ An initial value of 1 pm/V was reported by Myers et al. for the second-order nonlinearity in thermally poled silica.² The main difficulty associated with thermal poling is the spreading out that appears when patterned electrodes are used to create the χ⁽²⁾ grating structure. Recently, we discovered that poling in vacuo avoids the electrical breakdown in air that gives rise to this spreading out.³ In a previous paper⁴ we deserve creating a χ⁽²⁾ structure in a multimode fiber by poling in a vacuum evaporator using one periodic and one uniform electrode. The pitch of the mask was 20 μm, and a tilt between the fiber and the electrode pattern of about 45° was therefore necessary in order to achieve the pitch necessary (~28 μm) for quasi phase matching (QPM) at 830 nm.

© 1995 Optical Society of America