Abstract
We report low-loss, single-mode rib optical waveguides on-chip, fabricated using hot-embossing for the first time of radio-frequency sputtered \(\hbox {As}_{2}\hbox {Se}_{3}\) chalcogenide-glass thin films on a chalcogenide-glass substrate. Waveguides 4–6 \(\upmu \hbox {m}\) wide and \(1.9 \pm 0.1~\upmu \hbox {m}\) high are fabricated. Waveguide optical loss, using the Fabry–Perot technique, which is known to over-estimate loss, is found to be \(<\)0.78\(\hbox { dB cm}^{-1}\) for the TE mode, and \(<\)0.81 \(\hbox {dB cm}^{-1}\) for the TM mode, at 1,550 nm wavelength. Glass stability of the chalcogenide rib waveguides is excellent and is discussed in relation to the results of others.
Highlights
Molecular species exhibit characteristic vibrational absorption bands in the mid-infrared (IR) region of the electromagnetic spectrum (3–25 μm wavelength) (Seddon 2011)
Chalcogenide glasses exhibit transparent windows occurring within the range from the visible (e.g. from 500 nm for As40S60 to the mid-IR and passive mono-mode rib waveguides of high numerical aperture (NA) have been demonstrated
We present hot embossing of rib waveguides for the first time in a radiofrequency (RF)-magnetron sputter-deposited As40Se60 glass thin film on a Ge17As18Se65 glass substrate
Summary
Molecular species exhibit characteristic vibrational absorption bands in the mid-infrared (IR) region of the electromagnetic spectrum (3–25 μm wavelength) (Seddon 2011). Sonication in acetone lifted the photoresist beneath the undesired parts of the chalcogenide film, removing these; a second chalcogenide thermal deposition was made sequentially to produce rib waveguides (comprising: overclad./core/underclad.: air/Ge23Sb7Se70 rib: 1.2 μm wide and 100 nm high, sitting on a 400 nm Ge23Sb7Se70 slab waveguide/oxide coated Si wafer; waveguide optical loss: 0.5 dB cm−1 at 1,550 nm) In their later work (Hu et al 2010), strip waveguides (800 nm wide, 400 nm deep) of thermally-evaporated As2S3 were prepared by the same lift-off processing. It is shown here that waveguide loss in the sputter-deposited thin film is lowered as compared to that of a hot-embossed monomode rib waveguide in a thermally-evaporated As40Se60 glass thin film on a Ge17As18Se65 glass substrate (Lian et al 2009). Both of these sets of waveguides exhibited excellent glass stability; the glass stability of chalcogenide glass waveguides in general is briefly discussed
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