GouMax’s Polarization-Independent Quadruple Phase Demodulator is a 5-port optical module, as shown in Figure 1: one input port and 4 output ports. The phase modulated signal, carrying information of interests, such as physical parameters--temperature or strain, is injected to the quadruple phase demodulator through the input port S. The 4 outputs (M1 through M4) are sent to the optical power meters to convert to the electrical signals. By combining the information carried by the 4 outputs, one can recover the phase information of the input signal. The differential feature of quadruple outputs provides common-mode noise rejection and signal enhancement. Therefore, this feature greatly improves the signal to noise ratio.
