Photodetectors, both Linear and Photon Counting

DEFINITIONS:  "Linear" photodetectors have an ANALOG electrical output which is proportional to the optical input power.  "Photon Counting" detectors should be thought of as essentially DIGITAL devices which produce a 'click' or pulse when a photon event occurs.  Recording the signal consists of counting the pulses versus time.  The amplitude of the 'click' or pulse is not useful information as the gain of the signal electronics in the photon counting detector assembly is not well controlled.

We have UV photodiodes (photovoltaic devices), photoconductors and photomultipliers.  We have single photon counting avalanche photodiodes ("SPADs"). 

We offer a range of photodetectors spanning the spectrum from the ultraviolet to the infrared.  To see a detailed description of the functionality of the devices available (as well as a discussion of competing technologies), click to visit the following pages.  

• ultraviolet detectors (wavelengths shorter than 380 nm)
• visible and near IR range detectors (wavelengths from 380nm to 1600nm), for LIDAR and photon counting
• infrared detectors (wavelengths 2+ microns to 12+ microns) and CO₂ laser detection (nominal 10.6 microns)

Choosing a detector and, if necessary, an associated preamp and TE cooling device can be a confusing task.  The following summaries identify some of the issues to be aware of.

• How to choose an IR Photodetector
• How to choose a Preamp for your IR Detectors
• Warning on TE Cooling Devices

Additionally, some articles are available on this web site (in pdf format) which discuss photodetector technology.

• Uncooled LWIR Photodetectors in CO₂ Laser Beam Profilers
• Uncooled Photodetectors in YAG/CO₂ Laser Warning Receivers
• High-Speed Room-Temperature CO₂ Laser Photodetectors
• Predicting the Performance of a Photodetector
• Designers still choose mercury cadmium telluride