Linearity of a Silicon Photodiode at 30 MHz and Its Effect on Heterodyne Measurements.
The effect of optical irradiance on the linearity of a Si photodiode was studied. These results are compared for light modulated at 30 MHz and at dc as the optical irradiance was varied over a 9 decade range. We discuss how these results affect the use of this detector as a heterodyne receiver. As the optical irradiance varied from 10-2to 10+3mW/cm2, while maintaining constant total power, the photocurrent was constant to about 1%, but as the power density increased further, the photocurrent increased about 13%. At the highest densities that we could achieve, about 6×107mW/cm2there was only slight evidence of the onset of saturation. These results are of importance in our work to use optical heterodyne detection to measure filter transmittances over a wide dynamic range. The results provide guidelines for achieving maximum accuracy when using this particular diode as an optical heterodyne receiver.
National Institute of Standards and Technology, Gaithersburg, MD 20899.
Alan L
AL
Migdall
National Institute of Standards and Technology, Gaithersburg, MD 20899.
Carsten
C
Winnewisser
heterodyne; high frequency; irradiance; linearity; photodiode; saturation