Temperature Compensation - THORLABS APD450C Operation Manual

Â
(l) for a given wavelength can be read from the typical spectral responsivity curves (see
·
M
Appendix ).
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· The M-factor (gain) adjustment range for APD450C is 2 to 10 at 23°C ambient temperature.
· The amplifier's transimpedance gain G is 5 kV/A at 50 W.
The maximum output voltage of the APD450C is 2.0 V into 50 W. Depending on the
wavelength, the responsivity
uration at optical input power greater than CW Saturation Power listed in specifications. To
avoid saturation, keep the output signal below the specified maximum output voltage.
The ultra-low noise design includes an active low-pass filter to effectively suppress out-of-band
noise.
Please find typical curves for
Noise Distribution
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3.5.3 Temperature Compensation

Due to internal processes, the M-factor is temperature dependent. At a fixed reverse bias
voltage the M-factor will change with temperature: with lower temperatures the M-factor will in-
crease, with higher temperatures, it will decrease.
To compensate for this effect, the Thorlabs APD450C Avalanche Photodetectors carry a ther-
mistor that senses the temperature inside the APD450C enclosure. A special electronic circuit
controls the reverse voltage applied to the APD in accordance with the temperature change.
Since the M-factor depends on the applied reverse voltage, this reduces the temperature de-
pendency of the M factor. Please see the technical data for the M-factor
ity specifications and the section
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© 2020 Thorlabs
Â(l)
of the detector and the M factor, the amplifier will reach sat-
Responsivity
and M Factor Temperature Dependency
M Factor Temperature Dependency
, Output Frequency Response
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3 Operating Instruction
and
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in the chapter Appendix.
Temperature Stabil-
for typical curves.
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Spectral
7