Ultraviolet transparent silicon oxynitride waveguides for biochemical microsystems

Abstract

The UV wavelength region is of great interest in absorption spectroscopy, which is employed for chemical analysis, since many organic compounds absorb in only this region. Germanium-doped silica, which is often preferred as the waveguide core material in optical devices for telecommunication, cannot accommodate guidance below 400 nm, owing to the presence of UV-absorbing centers. We show that silicon oxynitride (SiO(x) N(y)) waveguides exhibit very good UV performance. The propagation loss for 24-microm -wide SiO(x)N (y) waveguides was found to be ~1.0dB/cm in the wavelength range 220-550 nm. The applicability of these waveguides was demonstrated in a biochemical microsystem consisting of multimode buried-channel SiO(x)N (y) waveguides that were monolithically integrated with microfluidic channels. Absorption measurements of a beta -blocking agent, propranolol, at 212-215 nm were performed. The detection limit was reached at a concentration of 13microM , with an optical path length of 500microm (signal/noise ratio, 2).

Femtosecond laser microstructuring: an enabling tool for optofluidic lab‐on‐chips

“…Propagation losses at 543 nm, measured using the cut-back technique, were found to be 0.9 dB/cm. This value is very promising as compared to those obtained at similar wavelengths in other kinds of waveguides integrated on LOCs and fabricated with SU-8 polymer (2.5 dB/cm) [21] and with SiON technology (1 dB/cm) [17].…”

“…Depending on the substrate of choice, different methods can be used. Approaches reported in the literature include waveguide fabrication by silica on silicon [14][15][16][17], ion exchange in soda-lime glasses [18,19], photolithography in polymers [20,21] and liquid-core waveguides [22][23][24][25]. All these methods suffer, when applied to LOCs, from several limitations: (i) they are inherently planar techniques, i. e. they are able to define optical guiding structures only in two dimensions, close to the sample surface; (ii) they are multistep methods, involving multiple masking with critical alignments; (iii) they require cleanroom environment, and (iv) they typically create uneven surfaces which make sealing of the microfluidic channels problematic.…”

Pure‐silica optical waveguides, fiber couplers, and high‐aspect ratio submicrometer channels for electrokinetic separation devices

“…The total coupling loss between the fibers and the planar waveguides was measured to 11 6 2 dB. This is higher than in our previous devices where the fiber coupling loss was around 8 dB [33]. …”

“…The wavelength dependence is expected, since scattering generally is more pronounced at shorter wavelengths [32]. Still, the propagation loss is lower than for the silicon oxynitride (SiON) waveguides previously published by our group [33], where 1.0 dB/cm was achieved between 230 and 550 nm. These SiON waveguides are furthermore no longer transparent at 200 nm due to absorption centers associated with the nitrogen dopant.…”

Monolithic integration of optical waveguides for absorbance detection in microfabricated electrophoresis devices

“…l eff is the effective * For more details on waveguides, their structure and the terminology used please refer to Section 2, Figs. 2-4, and [7,8,9,17,20,28]. length of the detection window and is defined as the length in absence of channel narrowing.…”