Generation of Complex Quantum States Via Integrated Frequency Combs

The generation of optical quantum states on an integrated platform will enable low cost and accessible advances for quantum technologies such as secure communications and quantum computation. We demonstrate that integrated quantum frequency combs (based on high-Q microring resonators made from a CMOS-compatible, high refractive-index glass platform) can enable, among others, the generation of heralded single photons, cross-polarized photon pairs, as well as bi- and multi-photon entangled qubit states over a broad frequency comb covering the S, C, L telecommunications band, constituting an important cornerstone for future practical implementations of photonic quantum information processing

Hydex Glass and Amorphous Silicon for Integrated Nonlinear Optical Signal Processing

Photonic integrated circuits that exploit nonlinear optics in order to generate and process signals all-optically have achieved performance far superior to that possible electronically - particularly with respect to speed. Although silicon-on-insulator has been the leading platform for nonlinear optics for some time, its high two-photon absorption at telecommunications wavelengths poses a fundamental limitation. We review the recent achievements based in new CMOS-compatible platforms that are better suited than SOI for nonlinear optics, focusing on amorphous silicon and Hydex glass. We highlight their potential as well as the challenges to achieving practical solutions for many key applications. These material systems have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement.Comment: 8 pages, 7 figures, 80 references in SPIE Volume 9516 Optics and Optoelectronics Photonics Europe 2015 pages 951606-951606-8. arXiv admin note: substantial text overlap with arXiv:1410.104

Discrete Optical Solitons

Discreteness is a basic property of nature itself. For example energy transport through polarons, excitons or defects depends critically on the internal molecular structure. Also complex macroscopic systems as waveguide arrays or discrete electrical lattices can be understood by an effective discretisation. This allows for the identification of basic principles and effects of discreteness, which are much more general than the model from which they are derived. One of the most interesting features of all these systems is the existence of robust solitary states, or discrete solitons: in this thesis we report the first experimental observation of discrete spatial optical solitons in arrays of waveguides. Light was coupled in the central waveguide. At low power, the propagating light widened its distribution as it coupled to more distant waveguides. When sufficient power was injected, light was localised close to the input waveguides and its distribution was successfully described by the discrete non-linear Schrodinger equation. By using a non-linear waveguide array we also demonstrate the distinct dynamical properties of discrete solitons, which are not found in the corresponding continuous systems. We observed non-linearly induced locking of initially moving solitons as well as the acceleration of resting solitons. These abrupt changes of the propagation angle with respect to the waveguide direction are a result of the lack of momentum conservation in discrete systems. Our work on optical arrays was concluded by the experimental investigation of the linear and non-linear optical response of a non-uniform waveguide array. By reducing the width of a single waveguide we decreased its effective index and induce waveguiding along the defect. Due to the positive non-linearity the index difference was reduced for increasing power levels with the result that the field escaped. Finally, with the aim of fabricating regions with different non-linearities in a same chip, we performed a comparison between the relevant non-resonant non-linear optical properties of an AlGaAs multiple quantum well heterostructure before and after intermixing. In particular, we experimentally investigated the wavelength dependence of the non-linear refractive index, two-and three-photon absorption and the ratio between self-phase modulation and cross phase modulation

Decoupling frequencies, amplitudes and phases in nonlinear optics

In linear optics, light fields do not mutually interact in a medium. However, they do mix when their field strength becomes comparable to electron binding energies in the so-called nonlinear optical regime. Such high fields are typically achieved with ultra-short laser pulses containing very broad frequency spectra where their amplitudes and phases are mutually coupled in a convolution process. Here, we describe a regime of nonlinear interactions without mixing of different frequencies. We demonstrate both in theory and experiment how frequency domain nonlinear optics overcomes the shortcomings arising from the convolution in conventional time domain interactions. We generate light fields with previously inaccessible properties by avoiding these uncontrolled couplings. Consequently, arbitrary phase functions are transferred linearly to other frequencies while preserving the general shape of the input spectrum. As a powerful application, we introduce deep UV phase control at 207 nm by using a conventional NIR pulse shaper