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- 摘要
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Optical Fiber Communications (Principles and Applications) || Optical Receivers
摘要： The purpose of a receiver in an electronic communication system is to extract the information sent by the corresponding transmitter with as minimum a carrier power level as possible. The primary function of an optical receiver in an optical fiber communication link is to convert the received optical signal into an equivalent electrical signal and recover the data. One of the main components of an optical receiver is a photodetector that converts incident optical signals into electric signals using photoelectric effects. High Sensitivity, dynamic range, fast response (i.e., acquisition time), high reliability, low noise, compatible size with that of fiber, and low cost are some of the important requirements of a photodetector. These requirements are best met by semiconductor photodetectors that convert an optical signal transmitted via optical fiber cables to equivalent electrical signals for further processing to achieve the desired output. The type of photodetectors suitable for three optical spectrum ranges of 800–900 nm, 900–1100 nm, and 1100–1600 nm vary in the material used for their fabrication as well as assembly techniques. A p–i–n photodiode is an ideal semiconductor photodetector device, because it can provide high quantum efficiency, fast response and capability to operate at higher modulation frequencies. The minimum received optical power that can be detected by a photodetector is limited by noise. A fully integrated single beam optical receiver comprises of a semiconductor photodiode, preamplifier in the electric domain, digital logic circuits, and an off-chip electronic driver circuit. This chapter discusses all the important aspects of photodetectors and optical receivers. The discussion begins with basic concepts behind the photo detection process, followed by description of different types of photodetectors usually used by optical receivers. Next, the components used in an optical receiver unit are explained. Finally, different types of noise sources in optical receivers that limit the signal-to-noise ratio, the receiver sensitivity parameter and its degradation are covered in sufficient detail.
关键词： Semiconductor Photodetectors,Noise Performance,Quantum Efficiency,Photodetectors,Avalanche Photodiode (APD),p–i–n Photodiode,Receiver Sensitivity,Responsivity,Optical Receivers
更新于2025-09-12 10:27:22
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Exploiting supramolecular assemblies for filterless ultra-narrowband organic photodetectors with inkjet fabrication capability
摘要： Narrowband photodetectors are useful for a myriad of applications involving color discrimination as well as biological imaging and machine vision. Prevalent devices use broadband light absorbing materials in conjunction with electric (charge collection narrowing, photo multiplication) and optical strategies (optical cavity) to narrow down the spectral response of the detector. Here we exploit the intrinsic narrow absorption width of B13–50 nm peculiar to J-aggregates of strongly coupled cyanine dye molecules for narrowband photodetectors. Albeit using ultrathin J-aggregate films (10 nm) unparalleled optical aggregate properties lead to high external quantum efficiency (15%) and response speed (15 kHz) at low bias voltage ((cid:2)1 V). We show that the self-assembly process and device architecture used permit the incorporation of J-aggregates of various cyanine dyes with photodetection maxima ranging from the visible to the near-infrared region up to 1000 nm. Narrow bandwidth (o50 nm) photodetectors fabricated by inkjet printing the active device layers including the J-aggregate film perform on par with spin-coated devices, thus underlining their industrial potential.
关键词： J-aggregates,organic photodetectors,cyanine dyes,narrowband photodetectors,inkjet printing
更新于2025-09-12 10:27:22
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Infrared plasmonic photodetectors: the emergence of high photon yield toroidal metadevices
摘要： Plasmon excitations in metallic nanostructures can decay directly into dynamic electronehole pairs, exploitable for photocurrent generation. This approach has extensively been employed to develop nanoplasmonic light-sensing devices with signi?cant responsivity and quantum ef?ciency. Among the devices, infrared plasmonic photodetectors have gained particular interest for their wide range of technological applications, including spectroscopy, biosensing, and surveillance. This Review discusses the fundamentals, recent advances, and trending mechanisms in the understanding and applications of plasmon-enhanced photocurrent generation in nanostructures across the infrared spectrum. By highlighting and comparing the developed techniques, we demonstrate the newly introduced directions toward achieving high photon yield infrared plasmonic photodetection tools. As a promising concept in modern metaphotonics, we present the emergence of toroidal meta-atoms as plasmon-induced carrier generators with unconventionally exquisite properties for designing advanced, rapid, and next-generation plasmonic photodetectors with signi?cantly high responsivity and photocurrent.
关键词： Photocurrent,Plasmonics,Infrared photodetectors,Plasmon-induced carrier generation,Toroidal photodetectors
更新于2025-09-12 10:27:22
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A new method to enhance organic photodetectors active layer trap doping by blending doping
摘要： In order to solve the problem of high concentration trap doping in the active layer of organic detector, a blending doping method is proposed in this paper. The influence of the doping concentration of C60:C70 on the trap concentration in the P3HT:PC61BM active layer and the optoelectronic performance of the detector are studied through experiments. It founds that the maximum doping concentration and trap concentration of active layer could arrive to 1.5 wt.% and 3.26×1018 cm-3 respectively after blending doping, which increased by 50% and one order of magnitude compared with the maximum doping concentration of single C60(doping concentration:1.0wt.%, trap concentration: 5.83×1017 cm-3), and the external quantum efficiency is increased by 8 folds from 1067.84% to 8510.17%. The result shows that the doping concentration and the trap concentration can be greatly improved using the blending doping method, and thereby the high concentration trap doping of the active layer can be achieved.
关键词： high doping concentration,blending doping,organic photodetectors
更新于2025-09-12 10:27:22
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Ultra-fast and high flexibility near-infrared photodetectors based on Bi2Se3 nanobelts grown via catalyst-free van der Waals epitaxy
摘要： van der Waals epitaxy (vdWe) method has recently attracted considerable interest due to its extensive application in the growth of layered structure materials. However, the growth process of vdWe is not completely understood. Here, we report the controlled growth process of Bi2Se3 nanobelts and study their photoresponse behaviour. The average length of nanobelts increases from 7 mm to 17 mm by adjusting the temperature of Bi2Se3 powder from 520 (cid:1)C to 530 (cid:1)C, however the average length becomes saturated with further increasing the source material temperature over 530 (cid:1)C. Such a change can be attributed to the competition between the process of Bi2Se3 molecule diffusion and the process of crystal formation-related chemical reaction, leading to a symmetrically studying for the growth process of catalyst-free vdWe growth of Bi2Se3 nanobelts. The photodetectors based on these Bi2Se3 nanobelts show excellent device performance in the near-infrared light range, including an ultra-fast photoresponse (trsing z 37 ms, tdecay z 62 ms), a high responsivity of 10.1 mA/W and a high detectivity of 4.63 (cid:3) 108 Jones. This high device performance could be related to the excellent carrier transport properties as Bi2Se3 nanobelt photodetectors also demonstrate a great potential for fabricating ?exible and wearable electronics by still showing stable photoresponse after bending the device for 200 times.
关键词： 2D NIR photodetectors,Catalyst-free van der Waals epitaxy,Bi2Se3 nanobelts
更新于2025-09-12 10:27:22
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Transparent multispectral photodetectors mimicking the human visual system
摘要： Compact and lightweight photodetection elements play a critical role in the newly emerging augmented reality, wearable and sensing technologies. In these technologies, devices are preferred to be transparent to form an optical interface between a viewer and the outside world. For this reason, it is of great value to create detection platforms that are imperceptible to the human eye directly onto transparent substrates. Semiconductor nanowires (NWs) make ideal photodetectors as their optical resonances enable parsing of the multi-dimensional information carried by light. Unfortunately, these optical resonances also give rise to strong, undesired light scattering. In this work, we illustrate how a new optical resonance arising from the radiative coupling between arrayed silicon NWs can be harnessed to remove reflections from dielectric interfaces while affording spectro-polarimetric detection. The demonstrated transparent photodetector concept opens up promising platforms for transparent substrates as the base for opto-electronic devices and in situ optical measurement systems.
关键词： augmented reality,wearable technologies,transparent photodetectors,silicon nanowires,spectro-polarimetric detection
更新于2025-09-12 10:27:22
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Optical Power Dependence of Capacitance in Uni- Traveling-Carrier Photodetectors
摘要： Optical power dependence of capacitance in uni-traveling-carrier photodetectors is analyzed by a model for capacitance calculation. The relationship between light-intensity-dependent capacitance and DC saturation characteristics of the device is found through the experiments and simulations.
关键词： uni-traveling-carrier photodetectors,capacitance,optical power
更新于2025-09-12 10:27:22
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Solution Processed MoS<sub>2</sub> Quantum Dots/GaAs Vertical Heterostructures based Self-powered Photodetectors with Superior Detectivity
摘要： The characteristics of a novel 0D/3D heterojunction photodetector fabricated using solution processed colloidal MoS2 quantum dots (QDs) on GaAs is being presented. MoS2 QDs with a dimension of ~2 nm, synthesized by standard sono-chemical exfoliation process of 2D layers have been used for the purpose. The microscopic and spectroscopic studies confirmed the formation of semiconducting (2H phase) MoS2 QDs. The photodetectors were fabricated using n-GaAs substrates with two different doping concentrations resulting in n-n heterojunctions between n-type 0D MoS2 QDs and bulk n-GaAs. The devices fabricated using GaAs having higher doping concentration, upon illumination, showed an increase of reverse current of the order of ~102, while the same with lower doping concentration showed an increase of the order of ~103. All the heterojunction photodetector devices show a broadband operation over the visible wavelength range of 400 – 950 nm, with a peak responsivity of the devices being observed at 500 nm. The peak responsivity and detectivity are found to be ~400 mA/W and ~4 × 1012 Jones, respectively even without any external applied bias, which are useful for self-powered photodetection. Results indicate that colloidal MoS2/GaAs based hybrid heterostructures provide a platform for fabricating broadband photodetectors by using highly absorbing MoS2 QDs, which may show the pathway towards next-generation optoelectronic devices with superior detection properties.
关键词： MoS2,detectivity,quantum dots,photodetectors,vertical heterostructure,GaAs
更新于2025-09-12 10:27:22
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Plasmonics-Integrated Ge PIN-Photodetectors
摘要： Refractive index sensors can be designed for high sensitivities at small device foot-print. Using a complementary metal-oxide-semiconductor compatible process for fabrication paves the way to cheap devices enabling integrated biosensors. We present results on combining vertical Ge PIN photodetectors with metallic nanostructures such as Al nanohole arrays placed directly on top of the diode. The interaction of plasmonic resonances and photonic modes such as waveguide modes or optical modes in nanostructured photodetectors can potentially be exploited to design refractive index sensors with very high sensitivities. We discuss how the interplay of material properties and device geometry can be tailored for applications in integrated biosensing.
关键词： CMOS,Plasmonics,Ge PIN-photodetectors,refractive index sensors,biosensors
更新于2025-09-12 10:27:22
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In Situ Monitoring Small Energy Storage Change of Electrochromic Supercapacitors via Perovskite Photodetectors
摘要： In situ monitoring the healthy state of energy storage devices is a smart way to avoid severe accidents and major emergencies. Electrochromic supercapacitors (ECSCs) stand out among other devices owing to the smart color variation during charge and discharge processes. However, it is hard to obtain the precise state of charge via only identifying their color change. To address this problem, an integral system composed of the inorganic CsPbBr3 perovskite photodetector (PPD) and polyaniline (PANI)//WO3 ECSC is proposed here. The PPD can simultaneously collect the variation of responsive current (under a green laser with the wavelength of 520 nm) when the ECSC is being charged or discharged. The real-time state of charge following the color change can be recorded by the PPDs constantly and accurately. A voltage alteration as small as 47.2 mV (charge variation of 0.33 mC) can be detected by this integral system rapidly, implying its great potential in managing the health condition of ECSC or even common energy storage devices in the future.
关键词： in situ monitors,small energy storage change,perovskite photodetectors,supercapacitors,electrochromic
更新于2025-09-12 10:27:22