Design and simulation of integrated photonic devices based on tilted Bragg gratings

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In traditional optics, instruments are made out of bulk components (mirrors, lenses, etc.) that are used to manipulate light. Unfortunately, it is very difficult and time consuming to align these components precisely and such devices tend to be large and heavy.The solution is to integrate the entire apparatus in a single optical chip. Light is routed around the chip in what are known as waveguides that confine light in a finite number of optical "states", which we call modes of the waveguide. The components that are used to process the light signals are themselves integrated into the chip. This is known as integrated photonics.One such component is the Bragg grating which consists of a periodic modulation of the refractive index of the material along a waveguide. The grating is able to couple light between different modes of the waveguide, for example between forward and backward propagating light in the same waveguide like a mirror operating at a certain frequency. A Bragg grating can also couple light between the waveguide and the surrounding material.A newly developed fabrication technology allows us to introduce a tilt angle to the planes of this periodic refractive index modulation. This gives rise to a new class of integrated photonic devices with higher efficiency, a wider range of design parameters, and completely new functionality.The aim of this project is to develop and simulate new devices based on tilted Bragg gratings for use in integrated photonic chips. We have already derived an equation quantifying the reflection of light by a grating to the surrounding material and have designed a new device that can transfer light between two waveguides with 100% efficiency. Other potential applications are in polarizing beam splitters, beam focusing, spectrometry, and quantum information processing.