Understanding aging in chalcogenide glass thin films using precision resonant cavity refractometry

Abstract

Chalcogenide glass (ChG) thin films have a wide range of applications in planar photonics that rely on the stability of their optical properties. However, most methods do not provide quantitative optical property data at sufficiently high resolution. We have employed a resonant cavity refractometry technique capable of detecting refractive index changes down to 10 −6 refractive index unit (RIU) to study the aging, or sub-T g structural relaxation kinetics, of Ge 23 Sb 7 S 70 ChG. Our study reveals that the refractive index (RI) change due to aging tends to follow stretched exponential behavior, with stretch exponents and rate of index change dependent on initial glass treatment. Thermally annealed devices show the best stability, suggesting that thermal annealing is the appropriate post-deposition treatment method for obtaining stable ChG films.

3D integrated photonics platform with deterministic geometry control

“…To achieve the target high sensitivity, the stress-induced resonant peak shift must be quantified and isolated from other interfering effects which also result in resonance drift, in particular temperature-dependent wavelength shift (TDWS) due to the thermal-optic effect and thermal expansion of the resonator materials. The TDWS in our resonator devices was measured to be 72 pm/°C [47]. The thermally induced resonance drift is thus much larger than our resonant wavelength measurement accuracy (below 1 pm [48]) even with small temperature fluctuations.…”

Filling in the missing link: monolithic optical isolators on silicon with high performance, broadband operation, and polarization diversity

“…The chemical stability and optical transparency of GeSbSe glasses have also been experimentally established [44][45][46][47] . Moreover, we have already matured fabrication protocols for low-loss ChG photonic devices including on-chip resonators with quality factors (Q-factors) exceeding one million 48 and applied the technique to realize a wide array of functional photonic components and systems [49][50][51][52][53][54][55] . The low deposition and processing temperatures of ChG further mitigates the risk of film cracking or delamination due to thermal stress accumulation 56,57 .…”

Role of annealing temperature on optimizing the linear and nonlinear optical properties of As40Se50Ge10 films

“…17,18 The aging process brings changes to the structural, mechanical, thermal and optical properties of glassy lms thus understanding the aging process is essential to both fundamental glass science and practical applications involving glassy materials. 19 The phenomenon of physical aging in chalcogenide glasses has attracted a substantial attention because of new prospects for chalcogenide-based optoelectronics. 20 The reason is that chalcogenide obtained in thermodynamically nonequilibrium state as frozen supercooled liquid owing to conventional meltquenching route 21 aspire with time to a more energetically favourable state, changing their exploitation parameters.…”