Related Experiment Video
Updated: Jun 10, 2026
09:38
Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies
Published on: December 18, 2015
Techniques for measuring small changes in the intensity of a pulsed laser
Applied Optics
|August 21, 2010
Summary
This study presents a novel technique using matched diodes in a bridge circuit to precisely measure small absorption or gain with pulsed lasers. This method significantly reduces errors caused by laser fluctuations, improving measurement accuracy.
Area of Science:
- Optical Physics
- Laser Spectroscopy
- Instrumentation
Background:
- Pulsed lasers exhibit pulse-to-pulse fluctuations, complicating precise absorption and gain measurements.
- Accurate measurements are crucial for advanced spectroscopic techniques.
Purpose of the Study:
- To develop and evaluate techniques for compensating laser pulse fluctuations in small absorption/gain measurements.
- To assess the applicability of these techniques to polarization-sensitive spectroscopy.
Main Methods:
- Utilized a bridge circuit with two matched photodiodes, one measuring the sample beam and the other a reference beam.
- Implemented a differential measurement to cancel out laser intensity variations.
- Tested with 8-ns pulsed lasers.
Main Results:
- Achieved a subtraction error of only 0.01% of the pulse area.
- The observed error was merely 1.5 times the shot noise limit.
- Demonstrated high precision in compensating for laser fluctuations.
Conclusions:
- The described diode bridge technique effectively compensates for pulse-to-pulse laser fluctuations.
- This method offers a robust solution for accurate small absorption/gain measurements.
- The technique shows promise for challenging applications like Raman-induced Kerr-effect spectroscopy.
