Reverse biased diode capacitance

I've been told an LED diode when it's reverse biased will act as a variable capacitor whose range is dependant on the amount of light falling on the diode junction. Does anyone have an approximate range of capacitance I would expect to find on a generic bright white LED?

Hi
I know that reverse capacitance is in rang pf but i don't know how it changes by lightening.
regards

This question intrigued me and I made an experiment. Red LED capacitance at 0V was 37pF in dark and 36.1pF when lighted with 100W bulb. Interesting.

The light causes generation of majority and minority carriers.And it effect is more pronounced for minority carries.Depletion region is made of minority carriers ,thus capacitance which is due to this depletion region also changes.

u have to check in lab.only lighting with 100 w watts bulb will not give u the exact data.remaining conditions r also applicable like natural light.

with capacitance that small you could have measured light generated current i guess.
may be it worth measuring the capacitance at different frequencies

I've seen an application using an LED and a pair of I/O pins on a micro controller that allows a single LED to work both as a light source, and a detector. Basically when the LED is reverse biased the capacitance of the diode charges, when you yank the power it discharges and the micro controller times the length of the discharge. Giving you at least the ability to use low baud transfers (300-2400baud or so) using only 1 extra I/O pin on an MCU and no extra external components. I can't test this for probably another month as I don't have my scope or breadboard set up where I'm at, but was hoping someone else had tried this. I do know that LED's are generally most sensative in the part of the spectrum immediatly bellow the colour that they emit when forward biased.

Phot detection priciple is based on that phenomenon.