A review of advances in pixel detectors for experiments with high rate and radiation

The Large Hadron Collider (LHC) experiments ATLAS and CMS have established hybrid pixel detectors as the instrument of choice for particle tracking and vertexing in high rate and radiation environments, as they operate close to the LHC interaction points. With the High Luminosity-LHC upgrade now in sight, for which the tracking detectors will be completely replaced, new generations of pixel detectors are being devised. They have to address enormous challenges in terms of data throughput and radiation levels, ionizing and non-ionizing, that harm the sensing and readout parts of pixel detectors alike. Advances in microelectronics and microprocessing technologies now enable large scale detector designs with unprecedented performance in measurement precision (space and time), radiation hard sensors and readout chips, hybridization techniques, lightweight supports, and fully monolithic approaches to meet these challenges. This paper reviews the world-wide effort on these developments.Comment: 84 pages with 46 figures. Review article.For submission to Rep. Prog. Phy

Integrated nanophotonic waveguide-based devices for IR and Raman gas spectroscopy

On-chip devices for absorption spectroscopy and Raman spectroscopy have been developing rapidly in the last few years, triggered by the growing availability of compact and affordable tunable lasers, detectors, and on-chip spectrometers. Material processing that is compatible with mass production has been proven to be capable of long low-loss waveguides of sophisticated designs, which are indispensable for high-light–analyte interactions. Sensitivity and selectivity have been further improved by the development of sorbent cladding. In this review, we discuss the latest advances and challenges in the field of waveguide-enhanced Raman spectroscopy (WERS) and waveguide infrared absorption spectroscopy (WIRAS). The development of integrated light sources and detectors toward miniaturization will be presented, together with the recent advances on waveguides and cladding to improve sensitivity. The latest reports on gas-sensing applications and main configurations for WERS and WIRAS will be described, and the most relevant figures of merit and limitations of different sensor realizations summarized

Chalcogenide Glass-on-Graphene Photonics

Two-dimensional (2-D) materials are of tremendous interest to integrated photonics given their singular optical characteristics spanning light emission, modulation, saturable absorption, and nonlinear optics. To harness their optical properties, these atomically thin materials are usually attached onto prefabricated devices via a transfer process. In this paper, we present a new route for 2-D material integration with planar photonics. Central to this approach is the use of chalcogenide glass, a multifunctional material which can be directly deposited and patterned on a wide variety of 2-D materials and can simultaneously function as the light guiding medium, a gate dielectric, and a passivation layer for 2-D materials. Besides claiming improved fabrication yield and throughput compared to the traditional transfer process, our technique also enables unconventional multilayer device geometries optimally designed for enhancing light-matter interactions in the 2-D layers. Capitalizing on this facile integration method, we demonstrate a series of high-performance glass-on-graphene devices including ultra-broadband on-chip polarizers, energy-efficient thermo-optic switches, as well as graphene-based mid-infrared (mid-IR) waveguide-integrated photodetectors and modulators

Micro-assembly of integrated photonic devices using a high accuracy transfer printing process

This thesis was previously held under moratorium from 03/12/19 to 03/12/21The overall objective of this thesis is the development and implementation of a high accuracy transfer printing (TP) technique for the micro-assembly of integrated photonic devices. The method has particular relevance for the integration of hybrid photonic waveguides, and enables the production of passive/active photonic circuit technologies in a parallel and scalable manner. The initial work involves the design of an optical microscopy based absolute crosscorrelation alignment technique utilised within a custom-built TP system. Following this, the statistical characterisation of the method, with the measured absolute positional accuracy of fully fabricated devices integrated across multiple substrates is achieved. An absolute lateral alignment accuracy of ±385 nm (3σ) and rotational accuracy of ±4.8 mrad (3σ) are demonstrated. This is reported as the highest lateral alignment accuracy to date for transfer printing, lending itself a significant advantage for the micro-assembly of optical waveguiding components. Utilising the high alignment TP system, the micro-assembly of fully fabricated single-mode Si membrane micro-ring resonators on a target silicon-on-insulator (SOI) substrate is presented. The ultra-thin membrane resonators are vertically integrated with Si bus waveguides situated on a receiver SOI chip in a highly controllable manner, demonstrating variation in resonant coupling conditions with respect to the lateral coupling offset. Further to this, the TP method provides a means to produce 3D device architectures without any limiting multi-step full wafer bonding methods. By vertical assembling 3D stacked membrane devices, a 100 µm2 SOI distributed Bragg reflector (DBR) is produced taking advantage of high lateral and rotation placement accuracy. The structure exhibits a visible wavelength reflectance band in agreement with theoretical simulations. The micro-assembly of hybrid AlGaAs-on-SOI micro-disk resonators is also presented, demonstrating the highly controlled integration of pre-fabricated waveguide devices across multiple material platforms. Control over the integrated resonator's vertical and lateral coupling to the bus waveguides enables the precise and selective excitation of different mode families within the resonator cavity. By using the high accuracy TP method, the vertical micro-assembly of hybrid micro-disk resonators also allows selective mode coupling, with loaded Q-factors reaching ~40,000. The unique advantage of the assembled devices however come from the ability to perform (3) nonlinear processes on SOI without being limited by two-photon absorption and free-carrier losses. Four-wave mixing is shown with efficiency levels of -25 dB at a low input power of 2.5 mW, with a nonlinear coeffcient of 325 (Wm)-1 demonstrated. The measured nonlinearity is comparable to its monolithic silicon counterpart, whilst also detailing a clear reduction in the nonlinear losses inherent to this material platform.The overall objective of this thesis is the development and implementation of a high accuracy transfer printing (TP) technique for the micro-assembly of integrated photonic devices. The method has particular relevance for the integration of hybrid photonic waveguides, and enables the production of passive/active photonic circuit technologies in a parallel and scalable manner. The initial work involves the design of an optical microscopy based absolute crosscorrelation alignment technique utilised within a custom-built TP system. Following this, the statistical characterisation of the method, with the measured absolute positional accuracy of fully fabricated devices integrated across multiple substrates is achieved. An absolute lateral alignment accuracy of ±385 nm (3σ) and rotational accuracy of ±4.8 mrad (3σ) are demonstrated. This is reported as the highest lateral alignment accuracy to date for transfer printing, lending itself a significant advantage for the micro-assembly of optical waveguiding components. Utilising the high alignment TP system, the micro-assembly of fully fabricated single-mode Si membrane micro-ring resonators on a target silicon-on-insulator (SOI) substrate is presented. The ultra-thin membrane resonators are vertically integrated with Si bus waveguides situated on a receiver SOI chip in a highly controllable manner, demonstrating variation in resonant coupling conditions with respect to the lateral coupling offset. Further to this, the TP method provides a means to produce 3D device architectures without any limiting multi-step full wafer bonding methods. By vertical assembling 3D stacked membrane devices, a 100 µm2 SOI distributed Bragg reflector (DBR) is produced taking advantage of high lateral and rotation placement accuracy. The structure exhibits a visible wavelength reflectance band in agreement with theoretical simulations. The micro-assembly of hybrid AlGaAs-on-SOI micro-disk resonators is also presented, demonstrating the highly controlled integration of pre-fabricated waveguide devices across multiple material platforms. Control over the integrated resonator's vertical and lateral coupling to the bus waveguides enables the precise and selective excitation of different mode families within the resonator cavity. By using the high accuracy TP method, the vertical micro-assembly of hybrid micro-disk resonators also allows selective mode coupling, with loaded Q-factors reaching ~40,000. The unique advantage of the assembled devices however come from the ability to perform (3) nonlinear processes on SOI without being limited by two-photon absorption and free-carrier losses. Four-wave mixing is shown with efficiency levels of -25 dB at a low input power of 2.5 mW, with a nonlinear coeffcient of 325 (Wm)-1 demonstrated. The measured nonlinearity is comparable to its monolithic silicon counterpart, whilst also detailing a clear reduction in the nonlinear losses inherent to this material platform

Transfer print techniques for heterogeneous integration of photonic components

The essential functionality of photonic and electronic devices is contained in thin surface layers leaving the substrate often to play primarily a mechanical role. Layer transfer of optimised devices or materials and their heterogeneous integration is thus a very attractive strategy to realise high performance, low-cost circuits for a wide variety of new applications. Additionally, new device configurations can be achieved that could not otherwise be realised. A range of layer transfer methods have been developed over the years including epitaxial lift-off and wafer bonding with substrate removal. Recently, a new technique called transfer printing has been introduced which allows manipulation of small and thin materials along with devices on a massively parallel scale with micron scale placement accuracies to a wide choice of substrates such as silicon, glass, ceramic, metal and polymer. Thus, the co-integration of electronics with photonic devices made from compound semiconductors, silicon, polymer and new 2D materials is now achievable in a practical and scalable method. This is leading to exciting possibilities in microassembly. We review some of the recent developments in layer transfer and particularly the use of the transfer print technology for enabling active photonic devices on rigid and flexible foreign substrates

Electronic Photonic Integrated Circuits and Control Systems

Photonic systems can operate at frequencies several orders of magnitude higher than electronics, whereas electronics offers extremely high density and easily built memories. Integrated photonic-electronic systems promise to combine advantage of both, leading to advantages in accuracy, reconfigurability and energy efficiency. This work concerns of hybrid and monolithic electronic-photonic system design. First, a high resolution voltage supply to control the thermooptic photonic chip for time-bin entanglement is described, in which the electronics system controller can be scaled with more number of power channels and the ability to daisy-chain the devices. Second, a system identification technique embedded with feedback control for wavelength stabilization and control model in silicon nitride photonic integrated circuits is proposed. Using the system, the wavelength in thermooptic device can be stabilized in dynamic environment. Third, the generation of more deterministic photon sources with temporal multiplexing established using field programmable gate arrays (FPGAs) as controller photonic device is demonstrated for the first time. The result shows an enhancement to the single photon output probability without introducing additional multi-photon noise. Fourth, multiple-input and multiple-output (MIMO) control of a silicon nitride thermooptic photonic circuits incorporating Mach Zehnder interferometers (MZIs) is demonstrated for the first time using a dual proportional integral reference tracking technique. The system exhibits improved performance in term of control accuracy by reducing wavelength peak drift due to internal and external disturbances. Finally, a monolithically integrated complementary metal oxide semiconductor (CMOS) nanophotonic segmented transmitter is characterized. With segmented design, the monolithic Mach Zehnder modulator (MZM) shows a low link sensitivity and low insertion loss with driver flexibility

Miniaturized Silicon Photodetectors

Silicon (Si) technologies provide an excellent platform for the design of microsystems where photonic and microelectronic functionalities are monolithically integrated on the same substrate. In recent years, a variety of passive and active Si photonic devices have been developed, and among them, photodetectors have attracted particular interest from the scientific community. Si photodiodes are typically designed to operate at visible wavelengths, but, unfortunately, their employment in the infrared (IR) range is limited due to the neglectable Si absorption over 1100 nm, even though the use of germanium (Ge) grown on Si has historically allowed operations to be extended up to 1550 nm. In recent years, significant progress has been achieved both by improving the performance of Si-based photodetectors in the visible range and by extending their operation to infrared wavelengths. Near-infrared (NIR) SiGe photodetectors have been demonstrated to have a “zero change” CMOS process flow, while the investigation of new effects and structures has shown that an all-Si approach could be a viable option to construct devices comparable with Ge technology. In addition, the capability to integrate new emerging 2D and 3D materials with Si, together with the capability of manufacturing devices at the nanometric scale, has led to the development of new device families with unexpected performance. Accordingly, this Special Issue of Micromachines seeks to showcase research papers, short communications, and review articles that show the most recent advances in the field of silicon photodetectors and their respective applications