Ben Haylock

Single-Crystalline 3C-SiC anodically Bonded onto Glass: An Excellent Platform for High-Temperature Electronics and Bioapplications

Single-crystal cubic silicon carbide has attracted great attention for MEMS and electronic devices. However, current leakage at the SiC/Si junction at high temperatures and visible-light absorption of the Si substrate are main obstacles hindering the use of the platform in a broad range of applications. To solve these bottlenecks, we present a new platform of single crystal SiC on an electrically insulating and transparent substrate using an anodic bonding process. The SiC thin film was prepared on a 150 mm Si with a surface roughness of 7 nm using LPCVD. The SiC/Si wafer was bonded to a glass substrate and then the Si layer was completely removed through wafer polishing and wet etching. The bonded SiC/glass samples show a sharp bonding interface of less than 15 nm characterized using deep profile X-ray photoelectron spectroscopy, a strong bonding strength of approximately 20 MPa measured from the pulling test, and relatively high optical transparency in the visible range. The transferred SiC film also exhibited good conductivity and a relatively high temperature coefficient of resistance varying from -12 000 to -20 000 ppm/K, which is desirable for thermal sensors. The biocompatibility of SiC/glass was also confirmed through mouse 3T3 fibroblasts cell-culturing experiments. Taking advantage of the superior electrical properties and biocompatibility of SiC, the developed SiC-on-glass platform offers unprecedented potentials for high-temperature electronics as well as bioapplications.

Anisotropic model for the fabrication of annealed and reverse proton exchanged waveguides in congruent lithium niobate.

An anisotropic model for the fabrication of annealed and reverse proton exchange waveguides in lithium niobate is presented. We characterized the anisotropic diffusion properties of proton exchange, annealing and reverse proton exchange in Z-cut and X-cut substrates using planar waveguides. Using this model we fabricated high quality channel waveguides with propagation losses as low as 0.086 dB/cm and a coupling efficiency with optical fiber of 90% at 1550 nm. The splitting ratio of a set of directional couplers is predicted with an accuracy of ± 0.06.

Frequency conversion between UV and telecom wavelengths in a lithium niobate waveguide for quantum communication with Yb+ trapped ions

We study and demonstrate the frequency conversion of UV radiation, resonant with 369.5 nm transition in Yb+ ions to the C-band wavelength 1580.3 nm and vice-versa using a reverse proton-exchanged waveguide in periodically poled lithium niobate. Our integrated device can interface trapped Yb+ ions with telecom infrastructure for the realization of an Yb+ based quantum repeater protocol and to efficiently distribute entanglement over long distances. We analyse the single photon frequency conversion efficiency from the 369.525 nm to the telecom wavelength and its dependence on pump power, device length and temperature. The single-photon noise generated by spontaneous Raman scattering of the pump is also measured. From this analysis we estimate a single photon conversion efficiency of 9% is achievable with our technology with almost complete suppression of the Raman noise.

Active demultiplexing of single photons from a solid-state source

A scheme for active temporal-to-spatial demultiplexing of single photons generated by a solid-state source is introduced. The scheme scales quasi-polynomially with photon number, providing a viable technological path for routing n photons in the one temporal stream from a single emitter to n different spatial modes. Active demultiplexing is demonstrated using a state-of-the-art photon source—a quantum-dot deterministically coupled to a micropillar cavity—and a custom-built demultiplexer—a network of electro-optically reconfigurable waveguides monolithically integrated in a lithium niobate chip. The measured demultiplexer performance can enable a six-photon rate three orders of magnitude higher than the equivalent heralded SPDC source, providing a platform for intermediate quantum computation protocols. (Figure presented.).

Nine-channel mid-power bipolar pulse generator based on a field programmable gate array

Many channel arbitrary pulse sequence generation is required for the electro-optic reconfiguration of optical waveguide networks in Lithium Niobate. Here we describe a scalable solution to the requirement for mid-power bipolar parallel outputs, based on pulse patterns generated by an externally clocked field programmable gate array. Positive and negative pulses can be generated at repetition rates up to 80 MHz with pulse width adjustable in increments of 1.6 ns across nine independent outputs. Each channel can provide 1.5 W of RF power and can be synchronised with the operation of other components in an optical network such as light sources and detectors through an external clock with adjustable delay.

Direct characterization of a nonlinear photonic circuit’s wave function with laser light

Integrated photonics is a leading platform for quantum technologies including nonclassical state generation1, 2, 3, 4, demonstration of quantum computational complexity5 and secure quantum communications6. As photonic circuits grow in complexity, full quantum tomography becomes impractical, and therefore an efficient method for their characterization7, 8 is essential. Here we propose and demonstrate a fast, reliable method for reconstructing the two-photon state produced by an arbitrary quadratically nonlinear optical circuit. By establishing a rigorous correspondence between the generated quantum state and classical sum-frequency generation measurements from laser light, we overcome the limitations of previous approaches for lossy multi-mode devices9, 10. We applied this protocol to a multi-channel nonlinear waveguide network and measured a 99.28±0.31% fidelity between classical and quantum characterization. This technique enables fast and precise evaluation of nonlinear quantum photonic networks, a crucial step towards complex, large-scale, device production.

Quantum tomography of a nonlinear photonic circuit by classical sum-frequency generation measurements

We propose and demonstrate a new method for the characterization of nonlinear multimode integrated devices that reconstruct the biphoton state produced trough spontaneous parametric down-conversion (SPDC) using classical sum-frequency generation measurements. The proposed method is experimentally demonstrated by predicting the state generated from a multi-channel integrated nonlinear waveguide device.