What is a balanced receiver?
Balanced receivers work by subtracting the photocurrent from two well-matched photodetectors. Common-mode noise that is present on both the reference and signal beams (such as laser-intensity noise) is cancelled out and thus doesn’t appear as part of the signal. On the other hand, any imbalance between the photocurrents generated by the reference and signal detectors, whether intentional or unintentional, is amplified and is seen as the signal. So with these balanced receivers, you can cancel out laser-intensity noise in any experimental setup that produces a reference signal achieving shot-noise-limited performance without the need for lock-in amplifiers. Applications include spectroscopy, ellipsometry, and heterodyne-detection experiments. (For more information download Application Note 7 on FM spectroscopy.
Balanced receivers work by subtracting the photocurrent from two well-matched photodetectors. Common-mode noise that is present on both the reference and signal beams (such as laser-intensity noise) is cancelled out and thus doesn’t appear as part of the signal. On the other hand, any imbalance between the photocurrents generated by the reference and signal detectors, whether intentional or unintentional, is amplified and is seen as the signal. So with these balanced receivers, you can cancel out laser-intensity noise in any experimental setup that produces a reference signal achieving shot-noise-limited performance without the need for lock-in amplifiers. Applications include spectroscopy, ellipsometry, and heterodyne-detection experiments.
