Optical Sensors - Photodiodes

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1540051EC3590

1540051EC3590

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SENSOR PHOTODIODE 940NM RADIAL

366

1541201EEA400

1541201EEA400

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SENSOR PHOTODIODE 940NM 1206

2685

1540051EA3590

1540051EA3590

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SENSOR PHOTODIODE 940NM RADIAL

718

1541141ECA570

1541141ECA570

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SENSOR PHOTODIODE 940NM 2SMD

2566

1540801EEA300

1540801EEA300

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WL-SDCB SMT PHOTODIODE CHIP BLAC

3607

1541021ECA170

1541021ECA170

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WL-SDSB SMT PHOTODIODE SIDEVIEW

4920

Optical Sensors - Photodiodes

1. Overview

Photodiodes are semiconductor devices that convert optical signals into electrical currents. Operating under reverse bias voltage, they generate electron-hole pairs when exposed to light, enabling precise light intensity measurement. As critical components in optoelectronics, photodiodes enable applications ranging from industrial automation to medical diagnostics, offering advantages like fast response times, high reliability, and compatibility with digital systems.

2. Major Types and Functional Classification

TypeFunctional CharacteristicsApplication Examples
PIN PhotodiodeWide depletion region for high quantum efficiencyHigh-speed optical communication (e.g., 10Gbps fiber links)
Avalanche Photodiode (APD)Internal gain through impact ionizationLIDAR systems, single-photon detection
Schottky PhotodiodeLow capacitance for fast switchingUV radiation monitoring in semiconductor manufacturing
Metal-Semiconductor-Metal (MSM)Planar structure for high-frequency operationOptical interconnects in data centers
UV PhotodiodeSpectral sensitivity below 400nmFlame detection systems, water purification monitoring

3. Structure and Components

Photodiodes typically consist of a p-n junction or p-i-n structure fabricated from silicon, germanium, or indium gallium arsenide (InGaAs). The core components include: (1) Light-receiving window with anti-reflective coating, (2) Active semiconductor layer for photon absorption, (3) Electrodes (anode/cathode) for current collection, (4) Ceramic or plastic package with optical filter integration. Advanced designs incorporate micro-lenses and back-illuminated structures to enhance quantum efficiency.

4. Key Technical Specifications

ParameterDescriptionImportance
Responsivity (A/W)Current output per unit optical powerDetermines signal strength at given irradiance
Dark Current (nA)Leakage current without illuminationImpacts signal-to-noise ratio in low-light conditions
Rise Time (ns)Response speed to intensity changesCritical for high-frequency modulation applications
Junction Capacitance (pF)Parasitic capacitance at depletion regionLimits bandwidth in transimpedance amplifier circuits
Spectral Response Range (nm)Effective wavelength detection windowDictates compatibility with light sources (e.g., 850nm VCSELs)

5. Application Fields

  • Industrial Automation: Object detection in conveyor systems
  • Medical Imaging: X-ray detectors in CT scanners
  • Consumer Electronics: Proximity sensors in smartphones
  • Telecommunications: 100Gbps coherent optical receivers
  • Environmental Monitoring: Solar radiation sensors for weather stations

6. Leading Manufacturers and Products

ManufacturerRepresentative ProductKey Features
Hamamatsu PhotonicsS1223-6BQHigh-speed Si photodiode with 1.3GHz bandwidth
OSRAM OptoBFW21RBlue-enhanced PIN diode for LiDAR applications
First SensorFDS030Low-noise APD for single-photon counting
Excelitas TechnologiesC30655GHInGaAs photodiode for 1.55 m telecom wavelengths
Vishay SemiconductorsBPW34SHigh-radiation hardness for industrial sensors

7. Selection Recommendations

Key considerations include: (1) Spectral matching with light source (e.g., InGaAs for 1550nm fiber systems), (2) Response time requirements (PIN vs APD tradeoffs), (3) Operating temperature range (-40 C to +85 C industrial grade), (4) Packaging constraints (SMD vs through-hole), and (5) Cost vs performance optimization (e.g., APDs require bias voltage regulators).

Industry Trends

Current development focuses on: (1) Graphene-based photodiodes for THz imaging, (2) CMOS-integrated single-photon avalanche diodes (SPADs) for LiDAR, (3) Flexible organic photodiodes for wearable devices, (4) Quantum dot photodiodes for extended IR sensitivity, and (5) AI-driven smart sensors with on-chip signal processing. Market growth is projected at 7.2% CAGR through 2028, driven by 5G optical networks and autonomous vehicle sensing systems.

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