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- ItemHigh-Resolution Arrayed-Waveguide-Gratings in Astronomy: Design and Fabrication Challenges(Basel : MDPI, 2017) Stoll, Andreas; Zhang, Ziyang; Haynes, Roger; Roth, MartinA comprehensive design of a folded-architecture arrayed-waveguide-grating (AWG)-device, targeted at applications as integrated photonic spectrographs (IPS) in near-infrared astronomy, is presented. The AWG structure is designed for the astronomical H-band (1500 nm-1800 nm) with a theoretical maximum resolving power R = 60,000 at 1630 nm. The geometry of the device is optimized for a compact structure with a footprint of 5.5 cm × 3.93 cm on SiO2 platform. To evaluate the fabrication challenges of such high-resolution AWGs, effects of random perturbations of the effective refractive index (RI) distribution in the free propagation region (FPR), as well as small variations of the array waveguide optical lengths are numerically investigated. The results of the investigation show a dramatic degradation of the point spread function (PSF) for a random effective RI distribution with variance values above ~10-4 for both the FPR and the waveguide array. Based on the results, requirements on the fabrication technology for high-resolution AWG-based spectrographs are given in the end.
- ItemSilicon-organic hybrid photonics: Overview of recent advances, electro-optical effects and CMOS-integration concepts(Bristol : IOP Publishing, 2021) Steglich, Patrick; Mai, Christian; Villringer, Claus; Dietzel, Birgit; Bondarenko, Siegfried; Ksianzou, Viachaslau; Villasmunta, Francesco; Zesch, Christoph; Pulwer, Silvio; Burger, Martin; Bauer, Joachim; Heinrich, Friedhelm; Schrader, Sigurd; Vitale, Francesco; De Matteis, Fabio; Prosposito, Paolo; Casalboni, Mauro; Mai, AndreasIn recent decades, much research effort has been invested in the development of photonic integrated circuits, and silicon-on-insulator technology has been established as a reliable platform for highly scalable silicon-based electro-optical modulators. However, the performance of such devices is restricted by the inherent material properties of silicon. An approach to overcoming these deficiencies is to integrate organic materials with exceptionally high optical nonlinearities into a silicon-on-insulator photonic platform. Silicon–organic hybrid photonics has been shown to overcome the drawbacks of silicon-based modulators in terms of operating speed, bandwidth, and energy consumption. This work reviews recent advances in silicon–organic hybrid photonics and covers the latest improvements to single components and device concepts. Special emphasis is given to the in-device performance of novel electro-optical polymers and the use of different electro-optical effects, such as the linear and quadratic electro-optical effect, as well as the electric-field-induced linear electro-optical effect. Finally, the inherent challenges of implementing non-linear optical polymers on a silicon photonic platform are discussed and a perspective for future directions is given.
- ItemFrom Lab-on-chip to Lab-in-App: Challenges towards silicon photonic biosensors product developments(Amsterdam : Elsevier, 2022) Mai, Andreas; Mai, Christian; Steglich, PatrickThis work presents and evaluates different approaches of integrated optical sensors based on photonic integrated circuit (PIC) technologies for refractive index sensing. Bottlenecks in the fabrication flow towards an applicable system are discussed that hinder a cost-effective mass-production for disposable sensor chips. As sensor device, a waveguide coupled micro-ring based approach is chosen which is manufactured in an 8” wafer level process. We will show that the co-integration with a reproducible, scalable and low-cost microfluidic interface is the main challenge which needs to be overcome for future application of silicon technology based PIC sensor chips.