Components for an Inexpensive CW-ODMR NV-Based Magnetometer

The false count rate of a single-photon-sensitive photoreceiver consisting of a high-gain, low-excess-noise linear-mode InGaAs avalanche photodiode (APD) and a high-bandwidth transimpedance amplifier (TIA) is fit to a statistical model. The peak height distribution of the APD's multiplied dark current is approximated by the weighted sum of McIntyre distributions, each characterizing dark current generated at a different location within the APD's junction. The peak height distribution approximated in this way is convolved with a Gaussian distribution representing the input-referred noise of the TIA to generate the statistical distribution of the uncorrelated sum. The cumulative distribution function (CDF) representing count probability as a function of detection threshold is computed, and the CDF model fit to empirical false count data. It is found that only k=0 McIntyre distributions fit the empirically measured CDF at high detection threshold, and that false count rate drops faster than photon count rate as detection threshold is raised. Once fit to empirical false count data, the model predicts the improvement of the false count rate to be expected from reductions in TIA noise and APD dark current. Improvement by at least three orders of magnitude is thought feasible with further manufacturing development and a capacitive-feedback TIA (CTIA).

A transimpedance amplifier (TIA) in the front-end of a radiation detector is required to convert the current pulse produced by a light-detector to a voltage pulse with amplitude and shape suitable for the subsequent processing. We consider in this paper the specifications of a positron emission tomography (PET) scanner for medical imaging. The conventional approach is to use an avalanche photo-diode (APD) as the light-detector and a feedback TIA. We point out here that, when the APD is replaced by the more recent silicon photomultiplier (SiPM), a feedback TIA is not suitable, and we propose the use of a regulated common-gate (RC-G) TIA. We derive the transimpedance function of the RC-G TIA considering the parasitic capacitances that have a dominant effect on the pulse shaping. We use the result obtained to establish TIA design guidelines, and we show that these should be different with an APD and with a SiPM at the input. We identify the dominant noise source in the RC-G TIA, and we derive a closed form equation for the output noise rms voltage. A prototype TIA was designed for UMC 130 nm CMOS technology. We present simulation and experimental results that confirm that the RC-G circuit is suitable for implementation of the TIAs in the front-end of a PET scanner using SiPMs at the input.

We create a working model of a magnetometer of a new type that is based on using cross-relaxation resonances in ensembles of NV-centers in diamond. This type of magnetometer does not require microwave radiation. For a sensor made out of a 300 micron diamond we demonstrate the magnetic field sensitivity of around 18 nT/Hz1/2. Keywords: cross-relaxation, NV-center, quantum magnetometer.

This paper focuses on designing dichroic filters for changing the color of light-emitting diode (LED) lamps. Dichroic filters are composed of multiple dielectric layers on a substrate. By applying a dichroic filter, some of the LED’s spectral energy is reflected and some is transmitted, which changes the lamp’s color. Conventional methods to obtain spectral transmittance curves have shortcomings. The design criteria for the transmittance curves are incompatible with the metrics used in lighting applications, such as correlated color temperature (CCT) and color rendering index (CRI). Thus, the color rendering performance and the optical transmission of a lighting system are not optimized. This observation leads to the development of a proposed method for designing dichroic filter transmittance curves to provide accurate color shift, high CRI, and sufficient optical transmission. The method initially uses the transmittance curve of an existing color filter that provides a roughly close color shift for the LED lamp to calculate the transmittance curve that causes an accurate color shift by polynomial approximation. Based on the approximated curve, a preliminary transmittance curve without the effect of the LED lamp’s secondary optics is derived and verified in thin-film design and optical design software tools. Further, the derived preliminary transmittance curve is optimized by applying an algorithm to loop through a large amount of representative curves fluctuating near the preliminary curve. The resulting dichroic filter provides an accurate color shift (ΔCCT = –800±50K, Duv = ±0.003), high CRI (Ra and R9 <= 95), and sufficient luminous flux transmission (<= 70%).

The U.S. Naval Research Laboratory (NRL) is characterizing InGaAs avalanche photodiodes (APDs) with internal structures engineered to reduce dark counts and ionization coefficient ratio (keff). Recently, much progress has been made in the use of APDs in linear mode for photon counting applications.1 However, the best results in linear mode single photon counting in InGaAs devices have been obtained by cooling the devices well below 200 K to reduce dark current. The single photon counting capability is due to the high gain available in the tail of the APD gain distribution, and this high gain tail is enhanced by reducing the ionization ratio (keff) and dark noise.2 Since recent promising results in linear mode APD photon counting have involved engineering the APDs to reduce keff, it is likely that these devices will also perform much better than standard APDs in free space lasercomm applications at temperatures which can easily be reached by thermoelectric coolers, or even uncooled, due to the keff reduction. NRL has obtained several InGaAs APDs of both the standard design and of a new design using impact ionization engineering from OptoGration, Inc. of Wilmington, MA. Some results of characterization of these APDs will be presented.

We report the design, fabrication, and test of a new InGaAs avalanche photodiode (APD) for short-wavelength infrared (SWIR) sensing applications at 950–1650 nm. The APD is grown by molecular beam epitaxy (MBE) on InP substrates from lattice-matched InGaAs and InAlAs alloys. Avalanche multiplication inside the APD occurs in a series of asymmetric gain stages whose layer ordering acts to enhance the rate of electron-initiated impact-ionization and suppress the rate of hole-initiated ionization when operated at low gain. Measurements have verified much lower excess multiplication noise and much higher avalanche gain than is characteristic of APDs fabricated from the same semiconductor alloys in bulk. At room temperature, multipli cation-enhanced APDs (MAPDs) of this design were found to have excess noise characterized by an effective ionization coefficient ratio of k = 0.02 to a gain of M = 100. The impulse response duration of a 75- m-diameter APD was measured to be less th an 1 ns when operated at a gain of M = 50, with a rise time of 225 ps and a fall time of 550 ps. High-rate single photon counting at 1064 nm was demonstrated with multiple 10-stage APDs operated below their breakdown voltage, using a commercial 2-GHz transimpedance amplifier (TIA) chip. Single photon detection efficiencies as high as 70% were measured for signal photon rates of 50 MHz. Keywords: avalanche photodiode, APD, single photon counting, laser communications, lasercomm, laser radar, LADAR

A novel equivalent circuit for separate absorption grading charge multiplication (SAGCM) APDs composed of basic circuit components is developed. The model is applied to simulate the frequency performance of APDs, and the simulating results show a well-reasonable agreement with the physical model calculation and experimental data. The influence of three important factors on frequency performance, including carrier transit time, avalanche buildup time, and parasitic elements (consisted of resistance, inductance, and capacitance of APDs) are investigated. Using this model, the cosimulation of the packaged APD\transimpedance amplifier (TIA)-module is also carried out. We found that the resonance of parasitic inductance and capacitance can be utilized to compensate the attenuation of high-speed APD\ TIA circuit board.

18 - Bias voltage and current sense circuits for avalanche photodiodes: Feeding and reading the APD

Body: III-Nitride (AlInGaN) avalanche photodiodes (APDs) have merits such as high breakdown field, high electron drift velocity, high thermal conductivity, and low dark current. The III-nitride material bandgap is tunable from 0.7 (1772nm) to 6.2eV (200nm), offering good UV sensitivity in both visible blind and solar blind UV regions. The Geiger-mode operation of III-Nitride APDs have numerous applications in UV single-photon detection, such as quantum-key distribution, optical time-domain reflectometry, positron-emission tomography, biomedical research, and UV communications. In this work, we report low-temperature Geiger mode measurements of GaN p-i-n APDs by using a thermoelectric cooling system. The GaN p-i-n APD structures were grown on c-plane hydride-vapor-phase-epitaxy (HVPE) free-standing (FS) GaN or ammonothermal bulk GaN. The epitaxially grown structure consists of a 0.6 mm unintentionally doped GaN, followed by a 2.3mm thick Si-doped GaN n-layer with a free-electron concentration of 4×1018 cm-3. The i-layer of 280nm thickness is grown on top of the n-layer, with a background Si doping of 2×1016 cm-3, targeting breakdown voltage of 96V. The p-layer stack consists of two layers of 100nm Mg-doped GaN and 15nm of highly Mg-doped GaN as the contact layer. The Mg-doped p-layer has a free-hole concentration of 1×1018 cm-3, and the highly Mg-doped p-layer has Mg concentration of 1×1020 cm-3. The fabrication of APD was performed in the following sequence: 1) mesa etching, 2) n-type metal deposition, 3) p-type metal deposition, 4) passivation and via-hole, and 5) metal interconnect deposition. A gated quenching circuit was used in the Geiger-mode measurement. In detail, a noninverting amplifier with gain of 2 and a transimpedance amplifier are inserted before and after the GaN APD in order to isolate the GaN APD and prevent reflection. An oscilloscope measures and collects the avalanche signals. A computer is utilized to perform signal data processing. For spectral response evaluation, the APD device is illuminated with the UV light from a UV LED with the peak wavelength of 375nm. The UV light is split by a bifurcated fiber: one end is fed to GaN APD, and the other end goes to an attenuator before being fed to a silicon photon counter for reference. For the low-temperature control, the thermoelectric cooler is installed directly under the GaN APD. The thermoelectric cooler is installed in an aluminum cage which serves as water-cooled heat sink. To prevent icing, the aluminum cage is sealed and filled with nitrogen. The Geiger-mode setup is installed in a optically isolated dark box. The method of measurement employed is the Δt method based on Poisson statistics. From the collected avalanche signal, the computer determines time interval between the rising edge of each pulse and its corresponding avalanche signal for 10,000 pulse events, then processes these time interval data into one histogram. Finally, by fitting the exponential function to the histogram, the dark count rate R is obtained. With this low-temperature Geiger-mode measurement system, the breakdown voltage was measured at various temperature from -10°C to 10°C with an increment step of 5°C. The breakdown voltage is proportional to the temperature, monotonically varying from 96.9V to 97.25V when the temperature increases from -10°C to 10°C. From this data, we obtained a temperature coefficient of the breakdown voltage of 0.0177±0.0005V/K. Based on the breakdown voltage vs. temperature, the dark count rate of various temperatures at 1V overvoltage above breakdown was measured. The dark count rate decreases as the temperature decreases from 19MHz to 11MHz when temperature decreases from 10°C to -10°C. By fitting Arrhenius equation, the obtained activation energy is . More detailed description will be presented in the conference. This work is funded by Support from ARO, DoE, NASA, Georgia Tech IEN, and the NSF National Nanotechnology Coordinated Infrastructure (NNCI)

A Transimpedance Amplifier (TIA) is a device commonly used in applications that require current-voltage conversion as well as the possibility of signal shaping. The most commonly used solution is to use an Avalanche Photo-Diode (APD) as radiation detector with a feedback TIA, but since the upcoming of the most recent Silicon Photo-Multiplier (SiPM), other TIA topologies have proven to be good alternatives. Our main objective in this paper is to show, evaluate and compare the behavior of a regulated common-gate (RCG) TIA when the light sensitive device is an APD or a SiPM. We will also study the usage of this circuit in a RF front-end, providing there is a passive mixer at the TIA's input. The proposed circuit is simulated with standard CMOS technology (UMC 130 nm), using 1.2 V power supply.

A high-performance InAlAs avalanche photodiode (APD) with a vertical-illumination structure for 50-Gbit/s applications is presented. The vertical-illumination structure we employed is advantageous for large optical tolerance and thus enables easier optical coupling than waveguide structures. Although the vertical illumination structure generally has disadvantages in terms of both responsivity and bandwidth, our fabricated APD exhibits a high responsivity of 0.69 A/W with a large 3-dB bandwidth of over 30 GHz at a multiplication factor (M) of 4.6 and a large gain-bandwidth product of 270 GHz, thanks to an unique hybrid absorption layer of p-doped/undoped InGaAs and a thin InAlAs avalanche layer. Furthermore, an optical receiver assembled with the APD and a trans-impedance amplifier (TIA) successfully demonstrates 50-Gbit/s error-free operation for the first time. The receiver sensitivity of -10.8 dBm at a BER of 10-12 is obtained against non-return-to-zero optical input signals at a wavelength of 1310 nm. In these operating conditions, the power consumption of the APD receiver module is less than 500 mW, where more than 98 % of the power is consumed by the TIA. The obtained minimum receiver sensitivity is enough for 20-km transmission at 50 Gbit/s when we assume a launch power of 0 dBm and transmission loss in the optical fiber of 0.5 dB/km. These results indicate our APD is promising for the systems with a serial baud rate of 50 Gbit/s such as 400-Gbit/s Ethernet systems.

Single-photon detectors (SPDs) play important roles in highly sensitive detection applications, such as fluorescence spectroscopy, remote sensing and ranging, deep space optical communications, elementary particle detection, and quantum communications. However, the adverse conditions in space, such as the increased radiation flux and thermal vacuum, severely limit their noise performances, reliability, and lifetime. Herein, we present the example of spaceborne, low-noise, high reliability SPDs, based on commercial off-the-shelf (COTS) silicon avalanche photodiodes (APD). Based on the high noise-radiation sensitivity of silicon APD, we have developed special shielding structures, multistage cooling technologies, and configurable driver electronics that significantly improved the COTS APD reliability and mitigated the SPD noise-radiation sensitivity. This led to a reduction of the expected in-orbit radiation-induced dark count rate (DCR) increment rate from ∼219 counts per second (cps) per day to ∼0.76 cps/day. During a continuous period of continuous operations in orbit which spanned of 1029 days, the SPD DCR was maintained below 1000 cps, i.e., the actual in-orbit radiation-induced DCR increment rate was ∼0.54 cps/day, i.e., two orders of magnitude lower than those evoked by previous technologies, while its photon detection efficiency was > 45%. Our spaceborne, low-noise SPDs established a feasible satellite-based up-link quantum communication that was validated on the quantum experiment science satellite platform. Moreover, our SPDs open new windows of opportunities for space research and applications in deep-space optical communications, single-photon laser ranging, as well as for testing the fundamental principles of physics in space.

본 논문에서는 3차원 영상을 위한 LADAR(LAser Detection And Ranging)용 광검출기 모듈을 설계-제작하고 그 특성을 측정한 결과를 보고한다. 광검출기 모듈은 광파이버 어레이와 접속될 수 있도록 200 um 직경을 갖는 InGaAs APD(Avalanche Photodiode)로 설계-제작하였으며, 선형모드 동작 특성을 만족하도록 TIA(Trans-impedance Amplifier)를 설계-제작하였다. 광검출기 모듈을 구성하는 핵심부품들은 12개의 lead pin을 갖는 TO8 상에 집적되었으며, 집적에 필요한 APD 서브마운트 및 TIA 회로 등을 자체적으로 설계-제작하여 사용하였다. 제작한 광검출기 모듈은 450 ps의 rising time과 780 MHz의 대역폭 특성을 보였으며, 0.8 mV 이하의 잡음 특성과, 150 nW의 MDS(Minimum Detectable Signal) 신호 크기에 대해 15 이상의 신호대 잡음비(SNR)를 보임으로써 설계한 모든 특성을 만족하였는데, 이는 저자들이 아는 한 200 um 직경의 대면적 InGaAs APD를 이용한 광수신기에서 가장 우수한 특성을 나타낸 것이다. In this paper, we report design, fabrication and characterization of the WBRM (Wide Band Receiver Module) for LADAR (LAser Detection And Ranging) application. The WBRM has been designed and fabricated using self-made APD (Avalanche Photodiode) and TIA (Trans-impedance Amplifier). The APD and TIA chips have been integrated on 12-pin TO8 header using self-made ceramic submount and circuit. The WBRM module showed 450 ps of rise time, and corresponding 780 MHz bandwidth. Furthermore, it showed very low output noise less than 0.8 mV, and higher SNR than 15 for 150 nW of MDS(Minimum Detectable Signal). To the author's knowledge, this is the best performance of an optical receiver module for LIDAR fabricated by 200 um InGaAs APD.

In any quantum communication system, such as a quantum key distribution (QKD) system, data rates are mainly limited by the system clock rate and the various link losses. While the transmission clock rate is limited by the temporal resolution of the single-photon detectors, losses in a fiber-based quantum communication system can be minimized by operating in the near infrared range (NIR), at 1310 nm or 1550 nm. Commercially available InGaAs-based avalanche photo-diodes (APDs) can be operated as single-photon detectors in this wavelength range [Hadfield, 2009]. Due to the severe after-pulsing, InGaAs APDs are typically used in a gated mode and this can limit their application in high-speed quantum communications systems. Superconducting single-photon detectors (SSPDs) can work in the NIR wavelength range with good performance [Gol’tsman et al. 2001; Hadfield, 2009]. However, SSPDs require cryogenic temperatures, and are not widely available on the commercial market at present. In addition, InGaAs/InP based photomultiplier tubes (PMT) can operate in the NIR range, but its performance is limited by very low detection efficiency (1 % at 1600 nm) and large timing jitter (1.5 ns) [Hamamatsu, 2005]. Microchannel plates (MCP) are micro-capillary electron multipliers coated with an electron-emissive material and multiply photon-excited electrons from a photon cathode [Wiza, 1979]. MCPs usually have faster rise times and lower timing jitter than is achievable with PMTs. InGaAs MCPs can work in the NIR range. These MCPs, but are limited by low detection efficiency (~1 %) [Martin, J. & Hink P. 2003]. On the other hand, silicon based avalanche photo-diodes (Si APDs) are compact, relatively inexpensive, and can be operated at ambient temperatures with high detection efficiency and low noise in the visible or near-visible range. Unfortunately they do not work at wavelengths longer than 1000 nm. For those wavelengths, an up-conversion technique has been developed that uses sum-frequency generation (SFG) in a non-linear optical medium to convert the signal photons to a higher frequency (shorter wavelength) in the visible or near visible range. The up-converted photons can then be detected by a Si APD. Up-conversion detectors use commercially available components and devices, and are a practical solution for many applications in quantum communications. To date, several groups have successfully developed highly efficient up-conversion single-photon detectors in the nearinfrared range using periodically poled lithium niobate (PPLN) waveguides [Diamanti et al., 2005; Langrock et al., 2005; Thew et al., 2006; Tanzilli et al., 2005; Xu et al., 2007;] and bulk crystals [Vandevender & Kwiat, 2004].

A gated InGaAs/InP single-photon detector based on a novel capacitance balancing technique was demonstrated. The single-photon detector is based on a gated InGaAs/InP avalanche photodioe. A quantum efficiency of 10% at 1550nm was obtained with a dark count probability per gate of 1.82×10 and an afterpulsing probability of 3.6% at a detection rate of 100 MHz. Moreover, compared with traditional capacitance balancing technique, our scheme can reduce dark count probability obviously. Introduction Near infrared single-photon detectors (SPDs) are widely used in many fields, such as quantum secure communication, astronomy, and ultrasensitive spectroscopy. The InGaAs/InP avalanche photodiode (APD) has been the most practical device for SPDs at telecommunication wavelength[1]. Since a photo-excited carrier grows into a macroscopic current output via the carrier avalanche multiplication in an APD operated in the Geiger mode, a single photon can be detected efficiently. However, some carriers trapped in the APD are subsequently emitted, and trigger additional avalanches that cause erroneous events. The InGaAs/InP APD in Geiger mode has a particular high probability that these so called “afterpulses” occur. Therefore, the InGaAs/InP APD is usually operated in the gated mode in which the gate duration (gate-on time) is generally set to a few nanoseconds. Then the interval between two consecutive gates is set to more than the lifetime (in orders of microseconds) of the trapped carriers so that the afterpulse is suppressed. The alternative SPDs at telecommunication wavelengths are frequency-upconversion-assisted Si-APD (upconversion detector) and a superconducting single-photon detectors (SSPD). Although these SPDs can be operated with greater voltages than gigahertz clock systems, they have drawbacks that make them difficult to apply to practical QKD systems. The upconversion detectors suffers from background noise counts with high detection efficiency, while the SSPD requires cryogenic below 4K. Thus far,several techniques, such as self-differencing technique[2], and sinusoidal gating technique[3], have been invented for InGaAs/InP single-photon avalanche photodioses(SPADs) in the gated Geiger mode, increasing the working speed over GHz. With these methods, SPADs can sense much weaker photon-induced avalanches at a high speed with good performance. However, it is quite difficult to change the gating frequencies of these SPADs, limiting their applications. Here, we propose the capacitance-balancing technique to solve the problem, easily tuning the gating frequencies without changing any state of the SPAD. At a detection rate of 200 MHz, we obtained a single photon detection efficiency of 10% with an afterpulse probability of 3.6% and a low dark count rate (1.82×10 per pulse). These make the device suitable for quantum secure communication, which requires that the bit error rate is less than 5%. 4th International Conference on Machinery, Materials and Computing Technology (ICMMCT 2016) © 2016. The authors Published by Atlantis Press 726