The TIA-527 balanced optical to electrical converter operates by subtracting the photo currents from two well-matched Indium Gallium Arsenide detectors. The result is then amplified and presented to the output port. Each of the optical signals causes the output to move with a different sense. Common mode signals (e.g. laser RIN noise) are effectively cancelled out. 

With selectable gain settings and a bandwidth of DC to 125 MHz this receiver is useful for coherent heterodyne detection applications, differential polarization or phase shifted keying modulation systems, spectroscopy, and similar applications for which the ability to discern small variations in signal strength in two optical paths is critical. 

Use of this converter can greatly simplify signal processing requirements downstream from the experiment. Gains of 1400 V/W, 14 000 V/W and 140 000 V/W may be selected as well as selectable AC inter-stage coupling. 

The unit is designed to be conveniently mounted on an oscilloscope input BNC connector and may be powered by its internal battery or with the universal wall-mount supply that is provided with each unit.