Avalanche Photodiode Receiver Research Articles

Leveraging InGaN solar cells for visible light communication reception

AbstractSolar cells are increasingly being utilised for both energy harvesting and reception in free‐space optical (FSO) communication networks. The authors focus on the implementation of a mid‐band p‐In0.01Ga0.99 N/p‐In0.5Ga0.5 N/n‐In0.5Ga0.5 N (PPN) solar cell, boasting an impressive 26.36% conversion efficiency (under 1.5AM conditions) as a receiver within an indoor FSO communication network. Employing a solar cell with dimensions of 1 mm in length and width, the FSO system underwent simulation using Optisystm software, while the solar cell's behaviour was simulated using SCAPS‐1D. The received power from the solar cell was then compared to that of four commercially available avalanche photodiode (APD) receivers. Exploring incident wavelengths spanning 400–700 nm within the visible spectrum, across transmission distances of 5, 10, 15, and 20 m, the study presented current‐voltage (IV) and power‐voltage curves. Notably, the InGaN solar cell exhibited superior electrical power output compared to all commercial APDs. In conclusion, the findings underscore that augmenting received power has the potential to enhance FSO network quality and support extended transmission distances.

Simulation analysis of underwater wireless optical communication based on Monte Carlo method and experimental research in complex hydrological environment

This paper aims to address the challenges of short optical communication distances and high Bit Error Rates (BERs) caused by seawater absorption, scattering, and underwater turbulence. This paper establishes an optical communication channel model based on the Monte Carlo method and simulates and analyzes the process of received optical power attenuation when light is transmitted underwater due to absorption and scattering. The simulation model focuses on the influence of seawater type, transmission distance, receiver position, and angle on the received optical power attenuation. The results of this simulation will provide theoretical support for the development of prototype underwater optical communication systems and experiments in complex environments. To solve the long-range weak signal reception and processing issues in underwater optical wireless communication systems, this paper proposes the design and implementation of an underwater optical wireless communication system using optimized on-off keying high-power light-emitting diode/laser diode modulation technology and avalanche photodiode (APD)/photomultiplier (PMT) receiver modules. In addition, this paper describes the design of the underwater optical communication host computer software, which provides functions such as mode selection, BER monitoring, and file transfer. To test the performance of the proposed system, this paper conducts experiments in a 35 m long pool, fixed platform, and underwater mobile platform, as well as cross-air-water interface optical communication performance test experiments in a complex hydrological environment. The results show that the system achieved a 35 m underwater medium communication distance, transmission rate of 5–20 Mbps, and cross-domain wireless optical communication function under the condition of a BER of less than 10−6. The experiments also revealed that the communication distance decreases as the turbidity of the water body increases and the PMT receiver module selected at the receiver end has a longer communication distance than the APD receiver module. Overall, this paper demonstrates the feasibility of the proposed technology for underwater optical communication systems in complex waters, providing theoretical and data support for the next engineering practice.

Avalanche Photodiodes With Dual Multiplication Layers and Ultra-High Responsivity-Bandwidth Products for FMCW Lidar System Applications

In this work, we demonstrate a novel In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.52</sub> Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.48</sub> As based top-illuminated avalanche photodiode (APD), designed to circumvent the problem of serious bandwidth degradation under high gain (>100) and high power operation and significantly enhance the dynamic range in the established frequency modulated continuous wave (FMCW) lidar system. In our APD design, the carriers transiting through the dual multiplication (M-)layers are subjected to a stepped-up electric field profile, so they can be energized by the first step and propagate to the second step to trigger the avalanche processes. Such a cascade avalanche process leads to an ultra-high gain bandwidth product (460 GHz) with a 1 A/W responsivity at unit gain. Compared to the high-performance and commercial p-i-n PD and photo-receiver (PD + trans-impedance amplifier (TIA)) installed in the same lidar test bed, our demonstrated APD receiver (without TIA) has a larger S/N ratio under high operation gain (33 A/W) with less optical local-oscillator (LO) power required (0.25 vs. 0.5 mW), while exhibiting a wider dynamic range in each pixel. These advantages in turn lead to the construction of a better quality of 3-D lidar image by using the demonstrated APD.

Performance analysis of an L-ary PPM MISO ground-to-satellite free-space laser link with an APD-based receiver over a Málaga turbulence channel in the presence of beam wander

In this study, the performance analysis of L -ary pulse position modulation ( L -PPM) and an avalanche photodiode (APD) receiver is investigated for a ground-station-to-low-Earth-orbit laser link. The performance is analyzed in the presence of spatial diversity in the transmitter side [i.e., a multiple-in single-out (MISO) scenario] under consideration of atmospheric turbulence and untracked beams where beam wandering effects occur. The modulated Málaga distribution is used to describe these two combined fading effects. At first, novel closed-form expressions of the probability density function and cumulative distribution function of Málaga distribution modulated by the beam wander effect in the case of MISO are deduced. We then derive an approximate expression for the upper bound of the average bit error rate (BER) in the case of L -PPM assuming a Gaussian model for the APD receiver in the presence of additive Gaussian thermal noise. The analytical expressions are verified by Monte Carlo simulations in the case of binary PPM, where the results are no longer upper bounds on the performance. Numerical results of the analytical upper-bound formula of the average BER are presented. For the system under consideration, the obtained results show that the effects of atmospheric turbulence and beam wandering for untracked beams can be effectively decreased by increasing the number of transmitters.

BER Performance of UWOC With APD Receiver in Wide Range Oceanic Turbulence

In this paper, the bit error rate (BER) performance of underwater wireless optical communication (UWOC) systems with on-off keying (OOK) modulation and an avalanche photodiode (APD) detector are analyzed in a wide range of oceanic turbulence environment, such as lognormal, Gamma, K, Weibull, and Exponentiated Weibull distributions. To achieving this goal, a new mathematical system model is established, which has not only considered the aggregated degrading phenomena, namely the absorption, scattering, and turbulence, but also been suitable for describing UWOC with APD receiver. Then the closed-form expressions of the BER performances of UWOC with APD for different turbulence distributions are derived in detail by subdividing the working situation into high and lower inter-symbol interference (ISI) scenarios. Theoretical analysis and computer simulations show that no matter what the ISI levels are, the derived closed-form expressions for system BER under various turbulences can approximate the accurate integral ones well. This is obviously helpful to the design and performance evaluation of UWOC systems.

Bit Error Performance of APD and SPAD Receivers in Optical Wireless Communication

This review concentrates on the state-of-the-art hardware-oriented receiver aspects for optical wireless communication (OWC), and points to the importance of BER performance analysis and modeling in presence of non-perpendicular light incidence. Receivers in OWC networks for 6G applications have to work for strongly different light incidence angles, to allow the formation of connections to locally separated transceivers without the need for rotation units and accurate adjustment. In turn, and in combination with fully integrated optical receivers, reduction of cost and increased comfort can be achieved. Fully integrated [bipolar] complementary metal-oxide-semiconductor ([Bi]CMOS) receivers with on-chip avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs) are presented and their performance in optical wireless communication is summarized. Impressive data rates up to 2 Gbit/s and free-space transmission distances up to 27 m at bit error ratios (BER) below 10−9 are reached with linear-mode APD receivers. The importance of optical interference in the isolation and passivation stack on top of the integrated photodiodes is illuminated. To be able to predict the dependence of the BER of single-photon avalanche diode (SPAD) receivers on the light incidence angle, a model, which includes a model for the photon detection probability and a standing-wave model for the isolation and passivation stack, is extended. The dependence of the BER on the light incidence angle onto the photodiodes is investigated by electromagnetic simulation for optical transmission of the layers on top of the photodiode, device simulation for the avalanche triggering probability and BER modeling with MATLAB. It is found that incidence angles up to 30° have moderate influence on the BER and that the BER degrades significantly for incidence angles larger than 50°.

Effect of the APD Receiver’s Tilted Angle on Channel Capacity for Underwater Wireless Optical Communications

This paper focuses on investigating the effect of the receiver’s tilted angle on the channel capacity of an underwater wireless optical communication (UWOC) system, in which an avalanche photodiode (APD) detector is adopted as the receiver. Under the non-negativity, peak power, and average power constraints, the lower bounds on the capacity of UWOC are derived in detail according to different average-to-peak power ratios. With modeling achieving the maximum of the lower bounds of the capacity as an optimization object, we prove that the proposed optimization issue is in fact a simple convex optimization about the tilted angle of the APD receiver, and then present related theoretical solution for it. Both theoretical analysis and simulation results show that by appropriately tilting the receiver, we can significantly enhance the final capacity performance of the UWOC with APD receiver.

Evaluation and experimental comparisons of different photodetector receivers for visible light communication systems under typical scenarios

Positive-intrinsic-negative diode (PIN), avalanche photodiode (APD), and single photon avalanche diode (SPAD) are commonly used optoelectronic receivers with different characteristics in practical visible light communication system. To determine the most appropriate candidate, different signal and ambient light strength in the communication scenarios should be taken into account. APD and SPAD receivers have higher sensitivities than PIN, but there are still some defects that restrain their operation performance. APD receiver may generate excessive shot noise, whereas SPAD is limited by the dead time, afterpulsing, and smaller detection area. We initially analyze the noise characteristics of PIN, APD, and SPAD receivers. SNR models are established, and the main factors affecting the performance of APD and SPAD receivers are concluded. Then, the comparison experiments of three kinds of receivers in various transmission distances are conducted, respectively. Finally, the experimental results show that: short and mid distance conditions, PIN and APD are better choices, whereas SPAD performs better in long-distance communication. In addition, if a certain intensity of ambient light is introduced, APD is still better than SPAD even in long distance.

Performance of UAV-to-Ground FSO Communications with APD and Pointing Errors

Recently, a combination of unmanned aerial vehicles (UAVs) and free-space optics (FSO) has been investigated as a potential method for high data-rate front-haul communication links. The aim of this work was to address the performance of UAV-to-ground station-based FSO communications in terms of the symbol error rate (SER). The system proposes utilizing subcarrier intensity modulation and an avalanche photo-diode (APD) to combat the joint effects of atmospheric turbulence conditions and pointing error due to the UAV’s fluctuations. In the proposed system model, the FSO transmitter (Tx) is mounted on the UAV flying over the monitoring area, whereas the FSO receiver (Rx) is placed on either the ground or top of a high building. Unlike previous works related to this topic, we considered combined channel parameters that affect the system performance such as transmitted power, link loss, various atmospheric turbulence conditions, pointing error loss, and the total noise at the APD receiver. Numerical results have shown that, for the best system SER performance, the value of an average APD gain at the Rx can be selected, varying from 18 to 30, whereas the equivalent beam waist radius at the Tx should be in a range from 2 to 2.2 cm in order to decrease the effects from the UAV’s fluctuations.

Performance analysis of APD and PIN diode with and without EDFA in GPON

Abstract Gigabit-capable passive optical network (GPON) is a passive optical network that provides faster data transmission and reception using point-to-multipoint access technology with single fiber. Using passive splitter in distribution network to keep the costs down, its 2.5 Gbits/sec bandwidth can be split up to 64 times. This paper presents the study of max Q-factor, min bit error rate (BER) using Opti system 17. In this study return to zero (RZ) and nonreturn to zero (NRZ) line codes analyzed by using P-insulator-N (PIN) and avalanche photo diode (APD) receivers. This paper also studies the impact of CW laser power on Q factor and min BER of GPON with and without erbium-doped fiber amplifier (EDFA).

Achieving high budget classes in the downstream link of 50G-PON

With 50G passive optical networks (PONs) currently being standardized, we review the challenges of meeting the high loss budgets required in such high speed fiber access networks. Simulations of the 50 Gb/s link performance show the impact of critical parameters when using 25G-class avalanche photodiode receivers with digital signal processing. We describe how a 1342 nm electro-absorption modulated laser, with an external semiconductor optical amplifier, enables an E2-class, 20 km, downstream link for ITU-T, 50G-PON to be demonstrated. Using a 25G-class receiver and real-time equalization, a link budget of 35.6 dB was measured. With more powerful equalization performed offline, an increase in the link budget to 38.2 dB is also demonstrated.

Simulation and experimental investigation of cross-phase modulation effect on 5G fronthaul wavelengths

Dense wavelength-division multiplexing is conceived as an appropriate solution for the 5G fronthaul system to cope with the rapidly increasing demand for bandwidth. While the cross-phase modulation (XPM) would appear when the signals are transmitted simultaneously in the single-mode fiber. The XPM effect on the 5G fronthaul wavelengths is investigated through both simulation and experimental campaigns. Simulation results show that the electrical spectrum crosstalk will occur with the wavelengths transmitting synchronously, when the channel spacing is 100 GHz and the speed is 25 Gbit / s per channel in the 10-km link. Also, the intensity of the electrical spectrum crosstalk becomes stronger when the launch power increases from 10 until 14 dBm. While comparing with the results obtained from the positive-intrinsic-negative (PIN) detector, the XPM-induced sensitivity penalty can be alleviated by 0.3 dB in use of avalanche photodiode (APD), which can provide higher signal-to-noise ratio. Consistent with the simulation results, the electrical spectrum crosstalk also appears in the experimental campaign under the same conditions. Furthermore, a sensitivity improvement of 0.5 dB is obtained using 25-GHz APD receiver, compared with the adoption of 35-GHz PIN receiver case.

BER performance analysis of FSO using hybrid-SIM technique with APD receiver over weak and strong turbulence channels

Abstract In this paper, a hybrid-subcarrier-intensity-modulation (hybrid-SIM) technique for the performance improvement of free-space-optical (FSO) communication system has been proposed. Subsequently, for further error performance improvement, avalanche photodiode (APD) based receiver is used in the proposed system. The system performance is analyzed at various atmospheric turbulence levels over weak and strong turbulence channels. The bit error rate (BER) is theoretically derived using Gauss–Hermite approximation and Meijer-G function and it is simulated in the MATLAB environment. The simulation result shows that the BER performance of hybrid-SIM is better than BPSK-SIM technique irrespective of the channel types and also the significant BER performance improvement is observed by APD receiver.

VLC Using 800-μm Diameter APD Receiver Integrated in Standard 0.35-μm BiCMOS Technology

The fully integrated 800 μm. diameter avalanche photodiode optical receiver is implemented in 0.35 μm BiCMOS technology without any process modifications. The integrated receiver reaches sensitivities of -33 dBm at 1 Gbit/s and -29.3 dBm at 2 Gbit/s. The reached sensitivities are well within the state-of-the-art of integrated avalanche photodiode receivers and can even be compared to a hybrid avalanche photodiode receiver comprised of high-performing commercial components. The performance of the designed receiver was verified in visible light communication experiments. The receiver could reach up to 16.5 m at 2 Gbit/s and 27 m at 1 Gbit/s of error free transmission distance using a 675-nm point laser source as transmitter. The common indoor illuminance levels up to 500 lux could be tolerated when pointed directly towards the receiver. High sensitivity and high speed make this integrated receiver suitable for future optical wireless communication systems, where due to its integrated nature the manufacturing cost can be lowered, and at the same time the design is compact in size and easy to assemble and scale. Furthermore, no optics is used in front of the receiver due to its large area resulting in a wide field of view.

Design and evaluation of a high-sensitivity digital receiver with the finite impulse response filter algorithm for free-space laser communication

We discuss the design of a digital laser communication receiver and its sensitivity test process. Laser communication is especially suitable for long-distance low-power micro–nano satellite links due to its narrow beam width, but the electro-optical noise situation of the micro–nano satellite platform is complicated and bad. Hence, it is necessary to introduce a digital laser communication receiver to flexibly suppress interference and noise to improve communication sensitivity. A digital laser communication receiver based on the avalanche photodiode (APD) is designed. Based on the principle of digital communication error probability, a high-sensitivity APD device is selected, and a digital receiving channel based on field programmable gate array is designed. The finite impulse response, the dynamic threshold, the baseband median, and other filtering algorithms are used to optimize the signal-to-noise ratio and enhance the detection sensitivity. At the same time, an 800-nm laser communication receiver sensitivity test experimental architecture is designed and the detection sensitivity experiment is carried out. The experiment indicates that the APD receiver achieves detection sensitivity at an Mbps rate better than −60 dBm. The digital filtering algorithm provides a filtering signal-to-noise ratio improvement of about 15 dB, which supplies a reference for the receiver design of micro–nano satellite laser communication.

Correction to: Optical wireless multiple-input multiple-output system based on avalanche photodiode receiver

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BER performance analysis of drone-assisted optical wireless systems with APD receiver

The integration of unmanned aerial vehicles (UAVs) and free space optical (FSO) systems has been recently proposed as a promising solution to establish flexible and high data rate backhaul/fronthaul links. However, due to the random fluctuations of hovering UAVs which cause optical beam fluctuations at the receiver, establishing UAV-assisted FSO links is technically challenging. In this paper, an avalanche photodiode (APD) at the optical receiver is utilized to successfully combat the effect of UAV’s fluctuations. To this aim, we first model the end-to-end signal-to-noise ratio (SNR) of an APD-based UAV-assisted FSO link. Then, given the analytical SNR model that we developed, closed-form expressions for the bit error rate (BER) of the considered system under different turbulence conditions are derived. The accuracy of the analytical expressions is verified by performing Monte Carlo simulations. Moreover, we study the effect of different link parameters, i.e., received optical beamwidth, the receiver field-of-view, optical transmit power, and different levels of UAV instability on the performance of the system. The results of this paper reveal insights into the importance of utilizing APD for UAV-based FSO system to mitigate the degradation effects of UAV’s fluctuations.

A Low-Voltage Si-Ge Avalanche Photodiode for High-Speed and Energy Efficient Silicon Photonic Links

Silicon-germanium (Si-Ge) avalanche photodiodes (APDs) have large gain bandwidth product (GBP) and low excess noise due to the low impact ionization coefficient ratio of silicon. Optical receivers using APDs are able to achieve high-speed and energy efficient optical transceiver systems. We demonstrate a waveguide Si-Ge APD with low breakdown voltage of −10 V, achieving 60 Gb/s PAM4 successfully. A compact APD circuit model was constructed to allow photonic devices and transceiver circuitry co-design. The APD receiver has achieved −16 dBm sensitivity at 50 Gb/s PAM4 with a bit error rate (BER) of 2.4 $\times \,10^{-4}$ . The sensitivity of APD receivers changes with the multiplication gain. In our analysis, compared to a PIN PD receiver the APD receiver operating at optimum gain can obtain $\sim$ 8 dB more sensitivity for NRZ signaling at $ 50 Gb/s and 3–4 dB more sensitivity for PAM4 signaling at 50–100 Gb/s. Also, the APD receiver operating at optimum gain can reduce power consumption by $\sim\!\text{10}\%$ at PAM4 data rates of 50 Gb/s and $\sim\!\text{15}\%$ at 100 Gb/s in a silicon carrier-depletion microring modulator based WDM photonic link.

Analysis and Design Consideration of a High Sensitivity Silicon Avalanche Photodiode Receiver for Low Frequency Applications

Silicon avalanche photodiodes (APDs) are designed predominantly for high-speed communication applications, but they can also offer interesting low-light application solutions in lower frequency bands. The design and analysis of a high sensitive silicon avalanche photodiode (APD) receiver for low-light fiber-optical sensor applications is described in this paper. The presented analysis shows relatively significant differences in the overall achievable signal-to-noise and distortion ratio (SINAD) of an optical receiver when using otherwise apparently very similar APDs. Furthermore, to maximize SINAD for the selected APD at a given target total receiver gain, an optimum setting exists between diodes’ internal gain (reverse voltage) and transimpedance gain. Unfortunately, these optimum settings are usually not determinable from the typical specification parameters that are given by APD suppliers, but rather need to be determined experimentally. A circuit with low-noise transimpedance amplifier (TIA) followed by post-amplifier and low-pass filter has, thus, been designed for measurement of the fiber-optical sensor signals with optical power less than 100 pW at 20 kHz bandwidth. The overall SINAD of a receiver circuit is highly dependent on APD excess noise and, therefore, several receiver circuits with different APDs have been built and tested. The receiver responsivity 5.5 GV/W and SINAD of more than 20 dB are achieved with the optimally selected APD.

Optical wireless multiple-input multiple-output system based on avalanche photodiode receiver

With the rising demand for high data-transmission rates, optical wireless communication (OWC) is considered one of the particularly appropriate solutions. In this paper, an avalanche photodiode (APD)-based optical wireless configuration is used to approximate the receiver output. This paper also presents bit error rate (BER) evaluation statistics compared with the theoretical results for optical wireless multiple-input multiple-output (MIMO) communication systems. In particular, the simulated results show that the BER of a 4 × 4 MIMO system is significantly lower than that of other APD systems (over 10 times better when the mean energy is higher than − 165 dBJ). To summarize, the OWC-MIMO system shows enormous potential in the high-speed data-transmission field.