Efficient second-harmonic generation into the UV by using optically encoded silicate glasses

Silicate glasses have been optically encoded to produce quasi-phase-matched second-harmonic generation with wavelengths as short as 340 nm. The effect is shown to be insensitive to the preparation wavelength over the range 686 to 766 nm. Readout of the encoded second-harmonic generation as a function of the fundamental wavelength detuning confirms that a periodic χ(2) grating is encoded into the glass. Experimental results show that the peak conversion efficiency occurs for readout wavelengths detuned slightly from the encoding wavelength. This is explained by absorption-induced index changes during the encoding process.