The balanced photoreceivers 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 doesn’t appear as part of the signal. Any imbalance between the photocurrents generated by the reference and signal photodetectors, whether intentional or unintentional, is amplified and is seen as the signal. This reduces common-mode noise by up to 40 dB so that you can see your signal.

These balanced optical receivers take the headache out of aligning and re-aligning your beams onto the photodetectors with their large detector diameters. This allows you to tweak your experiment without worrying about beam wander. Model 2317 has a 5-mm diameter Germanium photodiode covering 800-1700 nm.

The three-setting gain adjustment allows you to keep your signal from going off scale while you’re adjusting your experiment or measurement.

Newport's balanced optical receivers are ideal for optical detection applications that require sensitive measurements and increased signal-to-noise. Balanced photodetection is a method that can very effectively cancel common mode noise and detect small signal fluctuations on a large DC signal. Detection methods in the time domain (such as femtosecond ultrasonics and frequency modulation spectroscopy) and frequency domain (like absorption spectroscopy), and coherent heterodyne detection (such as optical coherence tomography) can be substantially improved by using Newport balanced photoreceivers and can allow detection of signals not otherwise possible with other means. For more information, please see our application note A Survey of Methods Using Balanced Photodetection.