High-speed Photo Research Articles

(Invited) Optical Biosensors in Photonic Integrated Circuits for Smart System Integration

Photonic integrated circuits (PIC) are like electronic integrated circuits drivers of communication systems. Moreover, state-of-the-art technologies enable the fabrication of electronic-photonic integrated circuits (ePIC), which allows for example the cointegration of ultra-fast BiCMOS devices with high speed photo detectors. Besides that, this technology provides an attractive platform for biosensors. They open the door for label-free detection of various analytes with high specificity and in real-time. This gives perspective to highly scalable and cost effective technologies for smart system integration of biosensors and electronic readouts to realize a true lab-on-a-chip application.We present the integration of optical biosensors in a Si-based PIC-technology. This comprises a front-end of line with optical waveguides, an integrated Ge-photodiode and a complete back-end of line consisting of three thin and two thick aluminum metal layers. The optical biosensor is integrated by opening the optical waveguide from the backside of the chip. In particular, we released a Si-based slot waveguide, which provides an enhanced evanescent field to interact with the analyte and hence to increase the sensitivity. The slot waveguide is incorporated in a ring resonator and we analyzed the wafer-level performance using the full width at half maximum, which allows us to assess the optical losses. Thermal sensing in a wide temperature range is investigated. In addition, a simple and cost-effective microfluidic is realized and we show initial results of the surface functionalization. Our work demonstrates the compatibility of a photonic biosensor with a photonic integrated circuit technology without any restriction to the standard FEOL and BEOL processing on the wafer front-side, while it keeps the inherent high sensitivity of evanescent-field sensing and opens a route towards smart system integration. Figure 1

CHARACTERISTICS OF PROCESSES SUBJECT TO VIDEO-PHOTOGRAPHY DURING TESTS OF ARMAMENT AND MILITARY EQUIPMENT OF THE GROUND FORCES AND DETERMINATION OF GENERAL REQUIREMENTS FOR PROSPECTIVE SAMPLES OF VIDEO-PHOTO EQUIPMENT FOR TESTING

Currently, during the period of active equipping and provision of the needs of the Armed Forces of Ukraine with new and modernized samples of armament and military equipment, there is an urgent need to conduct photo- video registration of the process during the testing of experimental samples with the help of photo and video equipment (cameras, video cameras, thermal imagers, etc.).
 The main problematic issue is that most of the systems and complexes of photo-video registration of information, which are operated in research laboratories of information and measurement systems of the Armed Forces and industrial enterprises of Ukraine, are outdated and have low technical characteristics.
 One of the possible ways to solve this issue is the analysis of physical processes that are subject to registration during tests, in order to determine the technical characteristics of photos and video equipment for their purchase for the operation of video surveillance test laboratories.
 The purpose of the research was to study the technical characteristics of modern photo and video equipment and the possibility of its use in testing weapons and military equipment for various functional purposes, primarily ground.
 This article analyzes the requirements for modern photo and video equipment, its technical characteristics and principles of operation. Domestic and foreign products were subject to analysis. The study of domestic and foreign experience in the use of such equipment shows that special attention should be paid to high-speed and television photo and video cameras when drawing up general requirements as they are the most complex in terms of construction.
 Thus, in order to improve the quality of tests of new and modernized samples of armament and military equipment, the technical characteristics of modern photo and video equipment and the possibility of their use during tests were investigated. The use of promising samples of on-board photo and video equipment during tests of armament and military equipment of the ground forces is possible with a wide range of applications.

Vertical organic phototransistors realized by femtosecond laser ablation patterned metal/insulator bilayer source electrodes: Performance and numerical modeling

Compared with their conventional lateral counter parts, vertical organic phototransistors (VOPTs) have the advantage of fast response speed due to short channel lengths, and may find wide applications in the field of high speed photo detection. By operation of VOPTs, the source electrode plays the vital role. We report on fabrication, characterization and analysis of VOPTs with pulsed laser ablation patterned Al/LiF bilayer source electrode. A maximal photoresponsivity of 760 mA/W, external quantum efficiency ( EQE ) of 145%, specific detectivity of 1.6 × 10 11 Jones were obtained for un-optimized devices. For describing the output characteristics of the devices, a rough numerical model was developed by combining the theory of thermionic emission at metal/organic interface and space charge limited current conduction. • We innovatively achieved the manufacture of vertical channel field-effect transistors by using a porous metal/insulator bilayer source electrode. • We patterned the porous electrode by femtosecond laser ablation. • We proposed a phenomenological device model to getting quantitative insight into the working mechanism of VOPTs. • The un-optimized device in this work showed a maximal photoresponsivity of 760 mA/W, EQE of 145%, specific detectivity of 1.6 × 10 11 Jones.

Effect of Si Doping on the Performance of GaN Schottky Barrier Ultraviolet Photodetector Grown on Si Substrate

GaN Schottky barrier ultraviolet photodetectors with unintentionally doped GaN and lightly Si-doped n−-GaN absorption layers were successfully fabricated, respectively. The high-quality GaN films on the Si substrate both have a fairly low dislocation density and point defect concentration. More importantly, the effect of Si doping on the performance of the GaN-on-Si Schottky barrier ultraviolet photodetector was studied. It was found that light Si doping in the absorption layer can significantly increase the responsivity under reverse bias, which might be attributed to the persistent photoconductivity that originates from the lowering of the Schottky barrier height. In addition, the devices with unintentionally doped GaN demonstrated a relatively high-speed photo response. We briefly studied the mechanism of changes in Schottky barrier, dark current and the characteristic of response time.

(Invited) Germanium-Tin Based Nano-Electronic and Photonic Devices

1. Introduction Germanium-Tin (Ge1-x Sn x ) alloy has many attractive properties that make it promising for many applications in nano-electronic and photonic devices and systems. GeSn has both higher hole and electron mobilities than Ge and Si to possibly enable scaling of the supply voltage for future high performance field-effect transistors (FETs). In addition, the tunable bandgap of GeSn by changing Sn compositions helps to extend the photo detection range beyond what can be achieved by Ge, covering wavelength larger than 1.55 µm.In this paper, we discuss the research and development of utilizing GeSn for various applications in nano-electronic and photonic devices. This includes multi-gate GeSn p-channel FETs (pFETs) on GeSn-on-insulator (GeSnOI) substrates, realization of ultra-low contact resistivity by incorporation Sn into Ge for the metal/GeSn S/D contact, and GeSn photodetectors for applications at 2 µm wavelength range. 2. GeSn pFinFETs with Sub-10 nm Fin Width on GeSnOI Substrates Large-area GeSnOI substrates were fabricated using direct wafer bonding (DWB) and layer transfer techniques at a 200 mm wafer scale [1]. This GeSnOI substrate, together with the multi-gate architecture, enabled the realization of high performance Ge1-x Sn x p-FETs with ultra-scaled channel length down to 50 nm [2]. An optimized try etch process was developed to fabricate GeSn FinFETs with fin width less than 10 nm. Excellent electrical characteristics were achieved with subthreshold swing of 63 mV/decade, intrinsic transconductance of 900 µS/µm at VDS of -0.5 V, and high-field effective mobility of 275 cm2/V·s. 3. Metal/ GeSn p-type Contact with Ultra-low Contact Resistivity. GeSn has a smaller hole Schottky barrier and a hole effective mass (mh ) as compared to Ge. These advantages make GeSn attractive for low-resistance p-type contacts. In-situ Ga doping was introduced during the epitaxial growth of GeSn using molecular-beam epitaxy (MBE) and more than 50% reduction of specific contact resistivity ρc has been observed by incorporation of 5% Sn into Ge [3]. Further optimization of GeSn doping process by surface segregation or cold implantation reduces ρc of Ti/p+-GeSn to sub-10-9 Ω-cm2 regime [4]. The ultra-low ρc of Ti/p+-GeSn is retained after anneal at 420 oC for 1 hour, showing adequate thermal stability for BEOL process in current CMOS technology [5]. 4. GeSn Photo-detectors for Applications at 2 µm Wavelength Range High-speed photo detection was demonstrated beyond traditional telecommunication bands and reaching at 2 μm band, realized by GeSn/Ge multiple-quantum-well (MQW) photodiode on Si substrate [6]. GeSn/Ge MQW structure was employed to increase the critical thickness (hc ) of epitaxial GeSn on Ge virtual substrate. A decent responsivity of 15 mA/W was obtained at 2 μm. A low leakage current density of 44 mA/cm2 was achieved at reverse bias of 1 V, which is among the lowest reported values for all GeSn photodiodes. A 3-dB bandwidth (f 3-dB) larger than 10 GHz was experimentally demonstrated directly at 2 μm. Acknowledgment We would like to acknowledge the funding support from Singapore Ministry of Education Tier 2 grants (R-MOE2018-T2-1-137 and MOE2018-T2-2-154).[1] D. Lei et al., Appl. Phys. Lett., 109, 022106, 2016.[2] D. Lei et al., VLSI Symposia, 2018, 197-198.[3] Y. Wu et al., J. Appl. Phys., 122, 224503, 2017.[4] Y. Wu et al., VLSI Symposia, 2018, 77-78.[5] Y. Wu et al., IEEE Electron Device Lett., 40, 1575-1578, 2019.[6] S. Xu et al., IEDM, 2018, 544-547.

The prototype of equipment protection system based on Ethernet POWERLINK for HALS

Abstract The Hefei Advanced Light Source (HALS) is brought forward to be a new diffraction limited storage ring (DLSR) light source. The technical pre-research project for the HALS is in progress. As an critical part of the project, a prototype of the equipment protection system (EPS) is developed to study the interlock protection for components of the light source. The prototype of the EPS is a distributed system based on Gigabit Ethernet POWERLINK (EPL) under EPICS architecture. A PC is used as the master managing node (MN), and 10 FPGA-based controllers is employed for the slave controlled nodes (CNs). EPL is used for the communication between the MN and CNs. This paper reports the design and results of a series of performance tests of the prototype system. The test results indicate that the prototype system can run stably with a communication cycle time 275 μ s , and the maximum global response time is about 870 μ s . This system is a feasible solution for the EPS of large-scale scientific facilities. In the further studies, the response time is expected to be further reduced by choosing high-speed photo couplers and properly arranged input signals.

High-speed photo detection at two-micron-wavelength: technology enablement by GeSn/Ge multiple-quantum-well photodiode on 300 mm Si substrate.

We report high-speed photo detection at two-micron-wavelength achieved by a GeSn/Ge multiple-quantum-well (MQW) p-i-n photodiode, exhibiting a 3-dB bandwidth (f3-dB) above 10 GHz for the first time. The epitaxy of device layer stacks was performed on a standard (001)-oriented 300 mm Si substrate by using reduced pressure chemical vapor deposition (RPCVD). The results showed promise for large-scale manufacturing. To our knowledge, this is also the first photodiodes-on-Si with direct radio-frequency (RF) measurement to quantitatively confirm high-speed functionality with tens of GHz f3-dB at 2 µm, which is considered as a promising candidate for the next data communication window. This work illustrates the potential for using GeSn to extend the utility of Si photonics in 2 µm band integrated optical transceivers for communication applications.

The dynamics of vocal onset

Vocal onset is the process occurring between the first detectable oscillatory glottal movement and the steady state vibration of the vocal folds. To some extent, the voice onset mirrors the voice offset. High speed imaging, photo-, electro-, flow- and ultrasonoglottography and sound analysis have been used in combinations to allow detailed qualitative insight into the phenomenon. Moreover, the instantaneous intraglottal pressure can be computed from the combined records of transglottal airflow and glottal area. A large number of vocal onsets of different types were analysed in various conditions of modal healthy phonation. Vocal folds (VF) vibration can start either from a closed glottis (hard onset) or from an open glottis (soft/breathy onset). In a soft onset, the amplitude of oscillations progressively increases over 2 to more than 30 cycles, before the first clear closed plateau is achieved. It is not possible to define whether the first movement of VF is towards medial or lateral. Hard, soft and breathy onsets can be clearly identified. Flow- and photoglottography are the most sensitive signals in detecting the first glottal movements in soft and breathy onsets. The shape of the EGG signal depends on the contact of the VF edges. The duration of the onset phase is to some extent related to VF adduction speed and peak expiratory flow. The ultrasound technique is sensitive, but lacks physiological interpretation. From the first onset-cycles on, the intraglottal pressure during the opening phase of the glottis exceeds that during the closing phase. During soft/breathy onsets with a sufficiently large number of cycles, when the vibrating mass increases, a trend appears toward a slight progressive decrease of the fundamental frequency of the oscillations, likely related to the increasing vibrating mass.

An Investigation of Regular Patterns of the Anode Spot Glow in a High-Current Vacuum Arc by the Method of High-Speed Photography

The evolution of an anode spot is investigated in the course of burning of a high-current vacuum arc. The evolution process is recorded with a high-speed video camera at a rate of 180 thousand frames per second and with a high-speed 4-channel photo camera, which is equipped with a set of interference filters to register the distribution of Cr I (428 nm), Cu II (625 nm) and Cr I + Cu II (500 nm) in the gap. The arc is ignited between two CuCr-electrodes measuring 20 mm in diameter in a vacuum arc chute imitating the operation of a vacuum circuit breaker by switch opening at a constant rate.

Microwave head imaging system using analogue fibre‐optic link for improved detection and localisation

The use of microwave photonics in the form of an optical link to transmit and receive microwave signals in microwave biomedical imaging systems is proposed. A single fibre is used to replace coaxial cables connecting the antenna array to the transceiver. The optical link, which is lightweight and offers an almost zero insertion loss, improves the signal-to-noise ratio and sensitivity, and thus offers better detection and localisation. As a proof of concept, an optical link that consists of a vertical-cavity surface-emitting laser, a multimode fibre and a high speed photo detector was built and tested. Experiments were performed using a 1–4 GHz microwave imaging system to scan a head phantom, which consists of accurately emulated brain tissues and embedded stroke. The head was imaged and the results were compared with those obtained using the traditional all-microwave link. The results demonstrate that the optical link increases the signal-to-noise ratio of the system and thus improves the quality of the obtained images and accuracy of the detection and localisation.

An experimental study of freezing of supercooled water droplet on solid surface

Results of experimental investigations of the freezing of immobile water droplet on an aluminum plate are presented. The process was studied with the aid of a high-speed photo camera. The freezing of supercooled water contained in the surface droplet proceeds in a few stages: (i) preliminary heating of water and nucleation of ice microcrystals, (ii) relatively fast formation of the ice–liquid system with a transition to the state of thermodynamic equilibrium near the freezing temperature, and (iii) slow process of complete freezing. The rate and duration of each stage and the time of delay between the moment of action upon the supercooled droplet and the onset of freezing are estimated. Processes of supercooled and nonsupercooled water solidification are compared.

A novel PWM power amplifier of magnetic suspension spindle control system for micro EDM

Considering the traditional power amplifier has the disadvantage of poor reliability and flexibility, a three-level pulse-width modulation (PWM) power amplifier which is based on a novel field-programmable logic gate array (FPGA) algorithm and hardware solution is proposed. The power amplifier can provide various signals flexibly and realize rapid response of the magnetic suspension spindle in micro-electrical discharge machining (EDM). In this paper, the principle of three-level PWM amplifier with half bridge and full bridge power circuit is introduced. According to different functions, the amplifier is divided into four function modules which include PWM signal generator module, voltage signal convert module, bootstrap drive module, and power bridge module. PWM signal generator module is also divided into four sub-modules in term of a new FPGA algorithm. Voltage signals are converted by high-speed photo coupler HCPL-2630. IR2110S chips are applied to drive the half bridge and full bridge power circuits. According to Kirchhoff voltage law, when the period of PWM signals is 50 μs and the duty cycles are larger than 0.76 and 0.665, the average current of half bridge and full bridge are more than 3 and 4 A; however, the ripple of the half bridge and full bridge are still less than 0.25 and 0.2 A, this advantage is suitable for the control system of magnetic suspension spindle. Test results of the average current and ripple are close to theoretical value. The axial response frequency of the spindle can reach 125 Hz, using this power amplifier and the magnetic suspension spindle, micro EDM can be achieved in Z axis with 1.2 mm stroke.

Image monitoring of pharmaceutical blending processes and the determination of an end point by using a portable near-infrared imaging device based on a polychromator-type near-infrared spectrometer with a high-speed and high-resolution photo diode array detector.

In the present study we have developed a new version (ND-NIRs) of a polychromator-type near-infrared (NIR) spectrometer with a high-resolution photo diode array detector, which we built before (D-NIRs). The new version has four 5 W halogen lamps compared with the three lamps for the older version. The new version also has a condenser lens with a shorter focal point length. The increase in the number of the lamps and the shortening of the focal point of the condenser lens realize high signal-to-noise ratio and high-speed NIR imaging measurement. By using the ND-NIRs we carried out the in-line monitoring of pharmaceutical blending and determined an end point of the blending process. Moreover, to determinate a more accurate end point, a NIR image of the blending sample was acquired by means of a portable NIR imaging device based on ND-NIRs. The imaging result has demonstrated that the mixing time of 8 min is enough for homogeneous mixing. In this way the present study has demonstrated that ND-NIRs and the imaging system based on a ND-NIRs hold considerable promise for process analysis.

Tunable ultra-narrow linewidth microwave generation from a double-loop Brillouin fiber laser

A simple photonic approach to generate an ultra-narrow linewidth microwave signal is proposed and experimentally demonstrated. In this scheme, a multi-wavelength Brillouin fiber laser (BFL) with a double-loop and un-pumped polarization maintaining erbium doped fiber (PM-EDF) is used. The double-loop configuration includes a 50 m long single-mode fiber (SMF) and a 10 m long SMF as Brillouin gain. The threshold and linewidth of the microwave source can be improved by using a double loop, while a 4 m long un-pumped PM-EDF is used to suppress unwanted side-modes. A dual-wavelength optical signal is heterodyned at the high-speed photo detector to produce a microwave signal by adjusting the polarization controller and the wavelength of the Brillouin pump. As a result, a tunable microwave signal from 10.605 to 10.887 GHz can be obtained. The linewidth of the microwave signal is about 14.4 kHz, and the side-mode suppression ratio is about 30 dB.

TU‐F‐BRE‐01: A High Resolution Micro Fiber Scintillator Detector Optimized for SRS and SBRT in Vivo Real Time Treatment Verification

Purpose:We have built a high resolution real time scintillating fiber detector prototype to determine in real time the accuracy of stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) treatments when only a fraction of the planned dose was delivered. The motivation of this work is to enhance dose delivery accuracy and to achieve error free radiosurgery.Methods:A high density array of scintillating fibers and a high speed photo detectors array were integrated to implement a high resolution real time dosimeter that can sample with high resolution pulsed SRS and SBRT beams cross sections. The high efficiency of the developed system allows to read each linac pulse in real time and to compute the accumulated dose and dose errors when only a fraction of the beam was delivered. The fibers are highly packed in a substrate that is directly coupled to two 128 pixel arrays with a pitch matching the fiber spacing to achieve accurate spatial localization. The small cross section of the fiber array allows stacking multiple fiber arrays to measure independent angular profiles that are digitally processed in parallel for real time dosimetry.Results:We implemented a high density array detector prototype with a pitch of 0.5 mm, readout speed of 1.2 msec, and a response time of 0.5 usec. The fast reading speed has the capability to determining the dose in flattening free filter beams. The detector can be installed in transmission mode at the output port of a micro‐MLC. Treatment deviations smaller than 3% are detected when less than 1/100 of the planned dose was delivered.Conclusions:We built a prototype of a high resolution fiber scintillator array detector for SRS and SBRT in vivo dosimetry. Results show that the developed detector has the potential to assure error free SRS and SBRT treatments.

Monolithic polarization diversity coherent receiver based on 120-degree optical hybrids on silicon

We present a monolithic polarization diversity coherent receiver by employing 120-degree optical hybrids on a silicon photonic integrated circuit (PIC). This PIC monolithically integrates silicon inverse tapers for fiber coupling, silicon polarization splitters, germanium high-speed photo detectors, and 120-degree optical hybrids based on 3x3 multimode interferometers (MMI). We demonstrate that 112-Gb/s polarization-division-multiplexed quadrature phase-shift keyed signals are detected in the wavelength range of 1530-1580 nm with comparable performance to commercial receivers.

Millimeter wave carrier generation based on Brillouin fiber laser with improved tuning capability

An all-optically generated millimeter wave carrier at 21.7GHz, 43GHz and 64.45GHz are experimentally achieved. These frequencies are realized by generating two consecutively laser wavelengths and are detecting on the 70GHz high-speed photo detector (HSPD). The initial mixing between the Brillouin pump and the second-order Stokes wavelengths is spaced by 0.178nm. This spacing, which is doubled from an inherently generated Stokes shift, is accomplished through an isolated circulation of the first order Stokes wave in the double Brillouin Stokes shifter (DSBS) built with 25-km single mode fiber. The generated millimeter carrier is measured at 21.7GHz, 43GHz and 64.4GHz achieved with BP power of 11mW, 30mW and 47mW, respectively.

High-Resolution 3D Laser Imaging Advances to Subcentimeter Precision

This article, written by Editorial Manager Adam Wilson, contains highlights of paper OTC 23006, ’SS MTS: Subsea Monitoring - High-Resolution 3D Laser Imaging for Inspection, Maintenance, Repair, and Operations,’ by C. Embry, M. Hardy, and B. Nickerson, 3D at Depth; N. Manning, CDL; D. Goodyear, UTEC Survey; and D. Richardson, SPE, and J. Pappas, SPE, RPSEA, prepared for the 2012 Offshore Technology Conference, Houston, 30 April-3 May. The paper has not been peer reviewed. 3D laser imaging is a powerful data-collection system that provides 3D information for a specific region of interest. Developing the technology to provide high-definition subsea laser imaging enables the deepwater industry to use the current state of the art in 3D metrology and related best practices developed for the terrestrial market. Terrestrial laser scanners commonly produce centimeter spatial and range accuracy at the several-hundred-meter range. Because of the absorption of water, realizable deepwater systems are limited to tens-of-meters range, depending on the target and water conditions. Here, subcentimeter accuracy from greater than 6 m is demonstrated for an underwater laser system. Introduction Sonar systems have been the main tools for measurement and survey for many years and have become very sophisticated. Many companies have developed high-resolution multibeam sonar systems that can produce angular resolutions as small as 0.2°. However, the resolution of these systems is fundamentally limited by the underlying physics; a wave-length of light is more than 108 times smaller than ultrasonic wavelengths and can achieve angular resolutions of less than 100 Μrad (0.006°). Therefore, light-based sensors inherently have higher spatial resolutions than sonar systems. The underwater 3D laser sensor presented here has the fundamental advantage of providing subcentimeter precision from greater than 7 m, a capability that, to the authors’ knowledge, has not been demonstrated previously. The Sensor The optical head [laser imaging unit (LIU)] consists of the transmitter subsystem (laser and accompanying optics), the receiver subsystem (detector and accompanying optics), and the scanner. These subsystems can be optimized for different operational scenarios and environ-mental conditions. For this prototype system, we used a diode-pumped, passively Q-switched, Nd:YAG laser with an external nonlinear crystal to perform the frequency doubling to 532-nm laser light. The receiver is a high-speed silicon photo diode, and the scanning subsystem is a two-axis galvanometer scanner to allow programmable scanning in two orthogonal directions. Along with the LIU are multiple electronic control systems. These include the control subsystem for controlling the LIU and monitoring-system health; the central processing unit and bus for general system control and operation; the data subsystem for data collection, transformation, and processing; the data-storage system for housing data locally; the power and environmental monitoring system to convert the host-vehicle power to the various voltages required by the sensor; and the input/output (communication) subsystem. All of these systems are housed within the subsea sensor (Fig. 1). The prototype sensor is 8.2 in. in diameter and 28 in. long and weighs 76.1 lbm in air.

Design on Large Power Traction Battery Formation Testing System of Electric Vehicle

Aiming at the current design research status on large power traction battery formation testing system of electric vehicle, this paper presents a system design method based on the management computer, the control computer and the output computer which is 3 layers construction including superior middle and inferior. In the hardware design, high-performance microcomputer is adopted as the main controller, high speed photo electricity coupling separated circuit is employed as the input and output interface, and pulse width modulation control method is used in control algorithm. In the software design, modular design is used to divide the software system into four function parts: data calculating and processing, data displaying, data storing, parameter setting and regulating.. At last, the data analysis of the system experimental results indicates that this kind of design method has a good application foreground.

A single InP-on-SOI microdisk for high-speed half-duplex on-chip optical links

We demonstrate for the first time that a single compact, electrically contacted indium phosphide based microdisk heterogeneously integrated on a silicon-on-insulator waveguide can be used as both a high-speed modulator and photo detector. We demonstrate high-speed operation up to 10 Gb/s and present bit-error rate results of both operation modes.