Silicon Photonic Components: Characterization and Optimization of Fabrication

Photonics is the science of manipulating photons, and silicon photonics is the application of silicon as the optical medium. It leverages the vast body of knowledge about semiconductor manufacturing and the established use of infrared wavelengths in telecommunications to simplify design, manufacture and testing. It also promises a relatively smooth integration of electronics and photonics. This work lays the foundation for further work with silicon photonics at NTNU. Starting with the bare silicon wafer, it explores the processing from scratch of the necessary materials and the nanostructuring of them to create devices. The entire process flow from the empty wafer to a device in the characterization lab is documented. Silicon-on-insulator wafers are grown using PECVD, and the film quality is evaluated. The wafers are patterned using EBL and etched with ICP-RIE. The bulk of the work is the development of etching recipes that minimize sidewall roughness. Simultaneously, the lithographic parameters of dose and spatial dimensions are optimized. Two candidate etch recipes are identified and their weaknesses and strengths relative to each other are discussed. Several mm long waveguides without discontinuities are fabricated, with features such as S-curves and racetrack resonators. These are characterized in an optical setup based on butt coupling with micrometer control of in- and out-coupling fibers, infrared imaging and a photodetector for quantitative measurement. The setup has been characterized and verified to work, however no coupling has been achieved. Suggestions for further work are outlined for the benefit of later researchers

Thick waveguides of low-stress stoichiometric silicon nitride on sapphire (SiNOS)

Low-stress stoichiometric silicon nitride (Si3N4) waveguides with an unprecedented thickness of up to 1350 nm and a width in the range of 2.2 - 2.7 µm are fabricated using a single LPCVD step on sapphire substrates (SiNOS). Optical characterization of proof-of-concept ∼1.35 µm thick waveguides show propagation losses in the order of 0.30 ± 0.01 dB/cm at 1600 nm. The proposed process offers a simple route to high confinement Si3N4 waveguides, enabling applications in nonlinear and mid-IR integrated photonics

En søppelvogn til begjær? Om sammenhengen mellom bruk av markedsmekanismer og innbyggertilfredshet med kommunale renovasjonstjenester.

Norske kommuner benytter i varierende grad konkurranse og markedsmekanismer til å organisere renovasjonstjenestene. De vanligste begrunnelsene for å innføre slike reformer er ønsket om å øke effektiviteten og redusere kostnadene. Det finnes imidlertid begrenset litteratur om hvordan kommunal organisering av tjenester påvirker brukertilfredshet, og de få unntakene som eksisterer, har hovedsakelig fokusert på sosialtjenestene. I denne artikkelen undersøker vi om innbyggere i kommuner som har innført konkurranseutsetting, benchmarking og offentlig–privat samarbeid, er mer fornøyd med renovasjonstjenestene, og vi bruker muligheten til å sortere søppel for gjenvinning og innhenting av husholdningsavfall som mål på tilfredshet. Analysen er basert på flernivåanalyse, som gir oss muligheten til å avdekke sammenhenger både på individ- og kommunenivå, i tillegg til å gi oss en bedre forståelse av variasjonen i tilfredshet mellom kommunene. Resultatene viser at det er ingen statistisk signifikante forskjeller mellom kommunene som bruker markedselementer i renovasjonstjenestene, og de som ikke bruker det

Redeposition-Free Deep Etching in Small KY(WO4)2 Samples

KY(WO4)2 is a promising material for on-chip laser sources. Deep etching of small KY(WO4)2 samples in combination with various thin film deposition techniques is desirable for the manufacturing of such devices. There are, however, several difficulties that need to be overcome before deep etching of KY(WO4)2 can be realized in small samples in a reproducible manner. In this paper, we address the problems of (i) edge bead formation when using thick resist on small samples, (ii) sample damage during lithography mask touchdown, (iii) resist reticulation during prolonged argon-based inductively coupled plasma reactive ion etching (ICP-RIE), and (iv) redeposited material on the feature sidewalls. We demonstrate the etching of 6.5 µm deep features and the removal of redeposited material using a wet etch procedure. This process will enable the realization of waveguides both in ion-irradiated KY(WO4)2 as well as thin KY(WO4)2 membranes transferred onto glass substrate by bonding and subsequent polishing

Residual Stress Analysis of Thin Film Materials for Fabricating Suspended Low Stress Si₃N₄ Waveguides on Sapphire

In this work the residual stress of various low temperature chemical vapor deposited (LPCVD) thin films on sapphire, viz. poly-silicon (poly-Si), stoichiometric silicon nitride (Si3N4) and silicon dioxide (SiO2), is analyzed using profilometric curvature measurements and stress diagnostic microstructures of as-deposited as well as annealed films. The found data is used to fabricate single deposition run, 1.35 μm thick, suspended low stress Si3N4 waveguide on sapphire. We foresee that this platform opens the way towards new photonic systems.</p

Light source, mems optical switch, sensor and methods for manufacturing the same

The present invention relates to a light source for generating an optical frequency comb. The present invention further relates to a method for manufacturing the optical resonator used in this light source. The present invention additionally relates to microelectromechanical systems, MEMS, optical switch and system comprising the same. The present invention also relates to a sensor and to a method for manufacturing a suspended silicon nitride structure comprised in the sensor. According to the present invention, a single-step LPCVD deposited monolithic stoichiometric Si3N4 layer is used on a mono-crystalline aluminum oxide substrate such as sapphire. The thickness of the Si3N4 layer exceeds 500 nm. This layer can be realized with relatively low residual stress