Large photo-induced index variations in chalcogenide-on-silicon waveguides

Abstract

The postfabrication modification of the group delay in silicon-photonic waveguides is proposed, simulated and demonstrated experimentally. Group delay variations of 2% are achieved through photo-induced changes to an upper cladding layer of photosensitive As₁₀Se₉₀ chalcogenide glass. The illumination of the cladding layer by intense green light for a few seconds leads to mass transfer and removal of material, away from irradiated regions. The phenomenon is employed in the localized removal of the cladding layer from above the core region of a silicon-on-insulator waveguide, thereby modifying its phase and group delays. Using the proposed method, the free spectral range of a chalcogenide-on-silicon Mach-Zehnder interferometer was modified by 1%. The technique is applicable to the postfabrication adjustment of the frequency response of silicon-photonic filters, comprised of several cascaded elements.

Selective light-induced mass transport in amorphous As x Se 100−x films driven by the composition tuning: Effect of temperature on maximum acceleration

“…The studies were performed on approximately 1 m thick films of AsxSe100-x with the value of x = 0, 2, 3,4,5,8,12,15,20,30, and 40 at%. The films were obtained by thermal evaporation of bulk ChG on glass substrates in vacuum 10 -3 Pa with relatively low deposition rates (3 -5 nm/s).…”

All‐optical wavelet‐based orthogonal frequency division multiplexing system based on silicon photonic integrated components

“…The resulting temperature gradient causes a fast lateral flow of the liquid layer from the hot regions to the cold ones [36]. We have been employing this effect in the selective photo-removal of the upper chalcogenide cladding layer from above regions of interest in the SOI PIC [37]. The photo-removal is permanent and provides the necessary tuning in device response.…”

“…The intermediate layer was required to reduce propagation losses due to the interface between Si and the chalcogenide layer. Finally, a 600-700 nm thick layer of As 10 Se 90 glass was deposited by thermal evaporation of a bulk target, in 0.5 μPa vacuum at 0.5 nm/s rate [37]. The The upper cladding was selectively removed from regions of interest by a 532 nm laser beam, coupled through a ×50 microscope objective lens.…”

Matrices pattern using FIB; ‘Out‐of‐the‐box’ way of thinking

“…Optical devices may be generally divided into two categories: single devices, such as an optical fibre (waveguide) (Bozhevolnyi, 2006;Califa, 2014) or logic circuits (Cohen, 2013(Cohen, , 2014; and an array of closely spaced structures (large matrices of circles, bowties, and others) that serve as a plasmonic platform (Fu, 2011, Salomon, 2013. Fabricating large matrices of nanostructures, including in plasmonics, poses multiple challenges -from maintaining high resolution over a large field of view (FOV; nanostructures that spread over hundreds microns) (Morrissey, 2005;Yao, 2010;Atiqah, 2012;Wilhelmi, 2012;Joshi-Imre, 2014), through reproducibility and accuracy of hundreds of structures at a time (Tseng, 2005;Yvonne, Xu, 2009Xu, , 2014, to system stability for extended writing.…”