In the field of optoelectronic devices,
biased detectors are a widely used category of specialized detection equipment. They are not devices with a single structure, but a general term for optical detection devices operating on the "reverse bias" mode. Their core lies in improving detection performance through external voltage regulation to meet the demand for high-precision optical signal capture in different scenarios.
I. The Nature of Biased Detectors
A biased detector is an optoelectronic device that requires reverse bias voltage during operation, mainly used to convert optical signals into measurable electrical signals. Essentially, it is based on ordinary photodetectors (such as photodiodes, avalanche photodiodes, etc.), and applies reverse voltage through an external circuit to change the electric field distribution inside the device, thereby optimizing the photoelectric conversion efficiency.
II.The Rationale for Bias Design
Ordinary unbiased detectors (such as photovoltaic detectors) can work, but they have obvious shortcomings in performance. The core purpose of bias design is to address these shortcomings and meet the requirements of detection scenarios with higher standards.
- Improves response speed: The strong electric field formed by reverse bias accelerates the movement of electron-hole pairs, significantly shortening the charge transmission time. This enables the detector to respond more quickly to rapidly changing optical signals (such as pulsed light) and avoids signal lag.
- Enhances detection sensitivity: The widened depletion region increases the interaction area between photons and semiconductor materials, allowing more sufficient absorption of weak optical signals. This enables the detector to capture weak light that ordinary devices cannot identify, making it suitable for low-light intensity scenarios.
- Reduces dark current interference: Reverse bias can suppress the dark current (leakage current without light irradiation) of the detector itself, reduce background noise, and make the output electrical signal purer, thereby improving measurement accuracy.
III.Application Scenarios of Biased Detectors
With the advantages of high response speed and high sensitivity, biased detectors have penetrated into multiple fields and become key devices for optical signal detection.
- Security and Surveillance: In infrared monitoring systems, biased infrared detectors can capture weak infrared signals at night to realize night vision imaging, which is widely used in security cameras, border monitoring and other scenarios.
- Medical and Bioimaging: In X-ray detection and fluorescence imaging equipment, biased detectors can accurately capture weak optical signals emitted by medical devices and convert them into clear electrical signals, assisting medical diagnosis.
- Industrial Detection and Sensing: In the quality inspection of industrial production lines, they can be used to detect surface defects of products (e.g., through laser reflected light signal analysis). They can also serve as core components of optical fiber sensing systems to monitor physical quantities such as temperature and pressure.
- Scientific Research and Aerospace: In astrophysical observation, they are used to capture weak optical signals from distant celestial bodies. In the aerospace field, they can be used as signal receiving devices in space radiation detection and optical communication.
