Characterization and estimated performance of commercial n+-p Ge APDs for long-wavelength optical receivers

For two commercial shallow-junction n⁺-p Ge APDs, it is shown empirically that the photocurrent multiplication and shot noise can be described over a wide range of wavelengths using expressions derived for single-carrier-type injection. Multiplied bulk leakage current and its associated shot noise may be similarly described, the closest agreement following from the use of photocurrent parameters applying at the longest wavelengths, 1.8m. These empirical relationships simplify the estimation of optical receiver sensitivity using Ge APDs. For bit rates up to several hundred megabaud, the performance of Ge APD receivers is expected to be inferior to that demonstrated by the high-impedance InGaAs pin—FET hybrid, particularly where operation in the range 40–60° C is specified. The two alternatives become competitive at 1 Gbaud, but the bias voltage for the Ge APD must be stable within several hundred millivolts and must be compensated for variations in temperature. Where unbounded disparity coding systems are employed, a hybrid receiver comprising a pin photodiode with a transimpedance preamplifier should still outperform the Ge APD for bit rates up to several hundred megabaud.     

A proposed ultra low-noise optical receiver for 1.55 μm applications

A high-sensitivity optical receiver based on InP/InGaAs superlattice avalanche photodiode (SL-APD) followed by an InGaAs MESFET transimpedance pre-amplifier has been proposed for operation in 1.55 m wavelength region. The proposed optical receiver may be realised in the hybrid integrated circuit form. The low excess-noise factor of the SL-APD significantly reduces the value of minimum detectable optical power and improves the sensitivity of the over all receiver. The proposed receiver has been analysed theoretically. The results of computation show that the device has a high transimpedance gain (60 dB-ohm) with a bandwidth of 11 GHz for a photodetector capacitance of 110 fF. The sensitivity of the receiver has been found to be (–27.3d Bm) at operating bit rate of 15 Gb/s for a bit-error-rate of 10^–9. The performance of the receiver can be optimised in respect of transimpedance gain, bandwidth and sensitivity by following guidelines provided in this paper. The proposed photoreceiver outperforms the existing receivers based on p-i-n/FET or conventional APD/FET photoreceivers.     

Noise performance of an InP/InGaAs superlattice avalanche photodiode

The noise performance of an InP/InGaAs Superlattice Avalanche Photodiode (SL-APD) has been studied theoretically to examine its suitability as a detector in optical receiver units. The results indicate that the device which has a very large gain-bandwidth product (450 GHz) provides a high receiver sensitivity compared to conventional APD. The device also exhibits a very low value of excess noise factor which results in a high value of signal-to-noise ratio. The SL-APD is expected to find useful applications as a high sensitivity photodetector in long-haul fibre optic communication systems. For a digital system, the device exhibits a very low value of bit-error rate (BER) even at moderate gain.     

Random response time of thin avalanche photodiodes

The avalanche built-up time using random response time model for avalanche photodiode (APD) is presented. A random response time model considers the randomness of times at which the primary and secondary carriers exit the multiplication region. The dead-space effect is included in our model to demonstrate its effect on response time of APDs especially for the thin devices. Our results show that feedback impact ionisation process and dead-space prolong the response time in APDs. The time response of homojunction InP p⁺-i-n⁺ diodes with the multiplication region of 0.281, 0.582 and 1.243 m are calculated.     

A high-speed optical receiver

The design and performance of a high-speed optical receiver for the 1.3m and 1.5m wavelength regions is described. The receiver comprises an InGaAs PIN photodiode feeding into a bipolar transimpedance preamplifier. Measured receiver characteristics are found to compare favourably with theoretical predictions.     

Simple approach to predict APD/PMT lidar detector performance under sky background using dimensionless parametrization

In this paper, we developed a simple approach to predict the APD/PMT (avalanche photodiode/photomultiplier) lidar detector performance in the presence of residual skylight background. By normalizing all relevant photodetector noise sources to the quantum noise, we obtain quantitative expressions for the degradation of the signal-to-noise ratio (SNR), the increasing threshold sensitivity of and decreasing lidar operation range. To apply the formalism to any lidar photodetectors operating in the ultra violet, visible and near-infrared spectral regions and to perform a comparative analysis of PMT and APD capabilities as the best photodetectors for ultra-violet (UV), visible (Vis) and near infra-red (NIR) lidar, we utilize a set of spectral characteristics that are built from an envelope of individual PMT and APD component responses. On this basis, the general analysis of system performance under intense background conditions is developed, and practical recommendations on detector use for each spectral region are given. The dimensionless formalism and the generalized detector spectral models used allows our analysis to be applied to nearly any lidar receiver operating over very different signal/background situations.     

红外通信波段SAGM APD单光子探测应用技术研究

研究采用由过度层间隔吸收区与倍增区的InGaAs/InP雪崩光电二极管(SAGM APD)在红外通信波段实现单光子探测的方法,包括管型的选择、特性分析、工作参数以及根据实验结果提出的对这类APD设计制作的改进建议.特别研究目前市售的APD器件用作单光子探测时的实用技术.     

单光子探测器APD无源抑制特性研究

为了选择高性能单光子探测器件，采用无源抑制方法对工作在盖革模式下的雪崩光电二极管（APD: avalanche photodiode）特性进行了测量。利用APD两端的电压在雪崩后趋于稳定的特性，获得了一种确定暗击穿电压的方法。特性测量实验结果表明：降低温度能加宽APD的最佳工作区域范围，并提高最佳增益值，从而使APD具有更高的灵敏度。通过对EG&;G系列APD和外延APD暗电流和信噪比特性进行比较，发现外延 APD具有良好的噪声性能和信噪比性能，适用于单光子探测。     

Thin-Film Luminescent UV Radiation Converters Based on Europium Chelates

This paper considers the possibility of using tris--diketonate complexes of europium in polymethylmettacrylate as luminescent UV radiation converters for widening the range of spectral sensitivity of photodetectors (including TV ones). The absolute quantum yields of luminescence have been determined. Converters for the 220–380-nm range providing a quantum efficiency of the silicon photodiode and the CCD matrix in the UV range up to 40% of the efficiency at the maximum of the spectral characteristic have been devised.     

Noise Immunity of a Laser Receiver with an Iodine Active Quantum Filter

The effect of a wide-range background exposure on the sensitivity of a laser receiver with an iodine quantum filter ( =1.315 m) is theoretically investigated. The sensitivity of the laser receiver is shown to be only about 12% less than the quantum limit when detecting optical signals against the background of the solar disk. It is also shown that in the case where the radiance temperature of a blackbody considered as a source of background radiation is 1.6· 10⁴ K, a twofold decrease in the sensitivity of the laser receiver is expected. The sensitivity of the receiver discussed is compared with that of a receiver with a visible-range photomultiplier tube. In the case of detection of optical signals against the background of the solar disk, the sensitivity of a receiver with an FEU-115 photomultiplier tube and interference filter ( 5 nm) is approximately 400 photons when the signal-to-noise ratio of the receiver is equal to unity.     

A simplified approach to digital optical receiver design

A simplified theory for the performance of a digital optical receiver is developed. The receiver sensitivity is calculated in terms of circuit parameters, received and equalized pulse shapes, photodiode parameters and bit-rate. An excellent agreement between this theory and a more complicated analysis by Personick [4] is demonstrated. It is shown that the receiver sensitivity may be improved by launching reduced-width pulses into the fibre, particularly if fibre bandwidth is a significant limitation. Reduced-width pulses bring benefits in source power consumption and lifetime, and in timing recovery.     

PIN versus Avalanche photodiode gain optimization in zero cross correlation optical code division multiple access system

In this paper, we show details of zero cross correlation (ZCC) code development and investigate performance by measuring bit-error-rates compared to other optical code division multiple access (OCDMA) codes using Avalanche photodiode (APD) and PIN photodetector. We present a configuration to determine how optical OCDMA systems can be applied with PIN and APD photodetector. Analysis of Avalanche photodiode gain optimization is discussed in ZCC code system. We also present analytical and numerical theoretical results for data transmission of spectrally encoded incoherent OCDMA signal and how signal-noise is being affected by using these two photodetectors.     

Laser bias effect on the receiver sensitivity of passive fibre optic star bus networks

We examine in this paper the reduction in receiver sensitivity in passive fibre optic star bus networks due to the laser bias power transmitted by every terminal. Both transimpedance and high impedance preamplifier configurations using PIN and avalanche photodiodes are considered. The penalty in receiver sensitivity is examined as a function of bit rate, number of terminals, amplifier noise and the ratio of the launched laser bias power to average launched signal power. For PIN receivers the penalty has a maximum at low bit rates and falls off rapidly on either side of the maximum. In an example quoted in the paper the PIN receiver sensitivity penalty for networks with less than 50 terminals is less than 1 dB for all bit rates. The penalty for APD receivers increases with bit rate, and, in a further example, is shown to be less than 1 dB for networks with less than 50 terminals operating at bit rates lower than approximately 20 Mbit s^?1. Techniques for reducing the penalty to negligible levels are also examined.     

Performance comparisons between inverted and conventional avalanche photodiodes for larger capacity applications

Optical Review - In this paper, two types of avalanche photodiode (APD) are compared, namely, a P-down APD using an inverted structure and a P-up APD using a conventional structure. Comparison...     

Quasi-Optical Sensors for Investigation of Acousto-Electromagnetic Phenomena of Popocatepetl Volcano

This article focuses on meteorological electronics based on the space research of acoustic-electromagnetic phenomena caused by Popocatepetl volcano (Mexico). The main purpose is to present two different types of quasi-optical sensors, one of them is formed by a modulator based on a surface oriented p,i,n structure with deep junctions; and by a silicon detector (avalanche photodiode with separated regions of absorption and multiplication: APDSAM). This system guarantee both good sensibility and wide range of sensing, sub-millimeter and millimeter range. This sensor has the advantage that can be realized as a planar array. On the other hand, for the remote measurement of basic meteorological parameters and chemical state by means of radiobrightness temperatures (radiometer systems) a low noise receiver on the base of dielectric waveguide and Schottky diodes cooled by means of cryoelectronic element is used.     

An improved design for Al Ga N solar-blind avalanche photodiodes with enhanced avalanche ionization

To enhance the avalanche ionization, we designed a new separate absorption and multiplication AlGaN solarblind avalanche photodiode(APD) by using a high/low-Al-content AlGaN heterostructure as the multiplication region instead of the conventional AlGaN homogeneous layer. The calculated results show that the designed APD with Al_(0.3)Ga_(0.7)N/Al_(0.45)Ga_(0.55)N heterostructure multiplication region exhibits a 60% higher gain than the conventional APD and a smaller avalanche breakdown voltage due to the use of the low-Al-content Al_(0.3)Ga_(0.7)N which has about a six times higher hole ionization coefficient than the high-Al-content Al_(0.45)Ga_(0.55)N. Meanwhile, the designed APD still remains a good solar-blind characteristic by introducing a quarter-wave AlGaN/AlN distributed Bragg reflectors structure at the bottom of the device.     

Dual-channel sis receivers for the iram Plateau de Bure Interferometer

The five antennas of the Plateau de Bure Interferometer have been instrumented with dual-channel receivers in the 3 mm and 1 mm bands. Polarisation diplexing allows simultaneous observations in the two bands. Each receiver has ambient and cryogenic calibration loads, and one receiver is equipped with a beam switching chopper for total power flux measurements. Typically the receiver noise temperatures are<50 K in both the 3 mm band and the 1 mm band. Initial observations show that at 115 GHz the sensitivity is doubled compared to the previous receivers, and high quality fringes have been obtained at 230 GHz. Preliminary experiments show that the receiver stability is good enough to correct atmospheric phase variations by monitoring the fluctuations in atmospheric emission at 225 GHz. VLBI fringes have been detected between one 15-m antenna and the IRAM 30-m antenna in Spain.     

A multi‐MHz single‐shot data acquisition scheme with high dynamic range: pump–probe X‐ray experiments at synchrotrons

The technical implementation of a multi‐MHz data acquisition scheme for laser–X‐ray pump–probe experiments with pulse limited temporal resolution (100 ps) is presented. Such techniques are very attractive to benefit from the high‐repetition rates of X‐ray pulses delivered from advanced synchrotron radiation sources. Exploiting a synchronized 3.9 MHz laser excitation source, experiments in 60‐bunch mode (7.8 MHz) at beamline P01 of the PETRA III storage ring are performed. Hereby molecular systems in liquid solutions are excited by the pulsed laser source and the total X‐ray fluorescence yield (TFY) from the sample is recorded using silicon avalanche photodiode detectors (APDs). The subsequent digitizer card samples the APD signal traces in 0.5 ns steps with 12‐bit resolution. These traces are then processed to deliver an integrated value for each recorded single X‐ray pulse intensity and sorted into bins according to whether the laser excited the sample or not. For each subgroup the recorded single‐shot values are averaged over ～10⁷ pulses to deliver a mean TFY value with its standard error for each data point, e.g. at a given X‐ray probe energy. The sensitivity reaches down to the shot‐noise limit, and signal‐to‐noise ratios approaching 1000 are achievable in only a few seconds collection time per data point. The dynamic range covers 100 photons pulse^?1 and is only technically limited by the utilized APD.     

A sensitive 3–4-mm radiometer

Improving the parameters of the Schottky barrier mixing diodes has permitted us to improve the sensitivity of the 3–4-mm radiometer described in [1]. The authors were able to achieve a fluctuation sensitivity of no worse than 0.15K for double-sideband reception with an output RC filter time constant of =1 sec by using, with several changes, the high-frequency part of this receiver. The sensitivity reached 0.1K at several points in the 3–4-mm range. Figure 1 shows a calibration record of a standard load, cooled in liquid nitrogen. The amplification while recording the noise was 30 times greater than for the calibration signal.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 21, No. 11, pp. 1702–1703, November, 1978.