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Message ID: 2421     Entry time: Tue Sep 17 23:42:41 2019
Author: Shalika Singh 
Type: Laser 
Category: PD QE 
Subject: Measuring Quantum Efficiency of Extended InGaAs Photodiode 

**[Internal Quantum Efficiency added]

[Koji, Shalika]

Further measurements were done after elog:2419 for Quantum Efficiency of Extended InGaAs Photodiodes(X8906). A Laser of wavelength 2um was used with an incident power of 0.80+0.02mW.  The Ophir RM9 power meter was used to check the incident power and also measure the reflectivity.

Attachment 1: The Setup. A Fibre launcher was used to project the laser along with a converging lens of the focal length of 40.0 mm which was further arranged with a subsequent converging lens of  150mm focal length. A mirror was used to reflect the laser light on the photodiode at an angle of 45o. The bias voltage was provided to pin 4 of photodiode using a Sallen Key low pass filter and the output at pin 3 of the photodiode was fed to a transimpedance amplifier (with a gain of 5.1k) which converted the photocurrent to voltage.

Attachment 2: The Quantum Efficiency is plotted with respect to different bias voltages, It was observed that the quantum efficiency increases with an increase in bias voltage. An External Quantum Efficiency of 77.4% was observed at 1V(maximum bias voltage for the photodiode). The Internal Q.E was observed to be 83.8% taking into account Reflectivity of (60.0+1) uW at an angle of 17deg. 

Attachment 3: To recreate all data

Attachment 1: IMG_8915.JPG  4.485 MB  Uploaded Thu Sep 19 01:58:10 2019  | Hide | Hide all
IMG_8915.JPG
Attachment 2: QE_X8906.pdf  23 kB  Uploaded Thu Sep 19 02:00:16 2019  | Hide | Hide all
QE_X8906.pdf
Attachment 3: Extended_InGaAs.zip  3.820 MB  Uploaded Thu Sep 19 02:00:41 2019
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