IV.27 - Photodiodes - General Info
(Note: there are several more specific sections on photodiodes in this FAQ.)
This section was contributed by Arvind K. Venkatesh, arvind@bu.edu.
A good introduction to photodiodes is: "A diode junction acts as a photodetector: Light creates electron-hole pairs, and there-fore a current throught the external ciruit. Diodes intended as photodetectors(photodiodes and PIN diodes) are packaged in a transparent case and are designed for high speed, high efficiency, low noise, and low leakage current" -- From 'The Art of Electronics' by Horowitz and Hill, Cambridge University Press, Cambridge.
A photodiode has two terminals, a cathode and an anode. It has a low forward resistance(anode positive) and high reverse resistance (anode negative). Most circuits utilizing photodiodes are for converting the output photocurrent to an voltage (I to V convertors for low photocurrents). Sometimes the voltage across the photodiode may also be measured.
The normal factors considered while selection of a photodiode include (but is not limited to) Responsivity (measure of the sensitivity of the photodiode to incident radiation), Spectral Response (Wavelength of light to be detected), Quantum Efficiency (Photodiode's capacity to convert light energy to electrical energy) and Response time (for speed of operation). The current trend is to combine the photodiodes with optical filters and associated electronics into a single package which is a solution for any particular light measurement or control problem.
A list of manufacturers of photodiodes are given below:
- Name: Centronic
Phone: 1-800-700-2088, 805-499-5902
Fax: 805-499-7770
Comments: Wide variety, customisable designs - Name: Sharp Electronics
Phone: 206-834-2500
Fax: 206-834-8903
Comments: Wide variety of photodiodes and other photo components - Name: Hamamatsu Photonics
Phone: 908-231-0960
Fax: 908-231-1218
Comments: Reputed to make the best photodiodes, wide variety of components. - Name: NEC
Phone: 1-800-366-9782 415-960-6000
Fax: 1-800-729-9288 - Name: Taitron Opto Devices
Phone: 888-TAI-OPTO 805-257-6060
Fax: 800-TAIT-FAX, 805-257-6415 - Name: Texas Instruments
Phone: 214-480-4546,214-917-1264
Comments: ask for "Intelligent Opto Sensors", they feature light to voltage and light to frequency convertors - Name: Burr-Brown
Phone: 1-800-548-6132
Fax: 602-741-3895
Comments: Make a combination of photodiode and amplifier - Detection Technology Inc.
Micropolis, 91100 Ii, FINLAND,
Tel. +358 8 553 6600
Fax +358 8 553 6611
E-mail: info@deetee.com
URL: http://www.deetee.com
Manufacturer of high-end photodiodes. Customized types available.