An optical receiver comprising: an optical resonator assembly including at least one optical resonator and a steering mechanism coupled to the at least one optical resonator , the at least one optical resonator being configured to receive a phase modulated input optical signal , to accumulate optical signal energy inside the at least one optical resonator based at least in part on the phase modulated input optical signal , and to produce an intensity modulated output optical signal , an intensity modulation of the output optical signal being representative of the phase modulation of the input optical signal , the at least one optical resonator being tuned to exhibit a symmetric phase change condition in the output optical signal at normal incidence of the phase modulated input optical signal on a surface of the at least one optical resonator ; an optical-electrical converter configured to detect the intensity modulated output optical signal and to convert the intensity modulated output optical signal into an electrical signal ; and signal processing and control circuitry coupled to the optical resonator assembly and to the optical-electrical converter , the signal processing and control circuitry being configured to receive the electrical signal , to perform symmetric phase change measurements based on the electrical signal , and to provide a control signal based on the symmetric phase change measurements to actuate the steering mechanism to steer the at least one optical resonator to maintain normal incidence of the phase modulated input optical signal on the surface of at least one optical resonator . an optical resonator assembly including at least one optical resonator and a steering mechanism coupled to the at least one optical resonator , the at least one optical resonator being configured to receive a phase modulated input optical signal , to accumulate optical signal energy inside the at least one optical resonator based at least in part on the phase modulated input optical signal , and to produce an intensity modulated output optical signal , an intensity modulation of the output optical signal being representative of the phase modulation of the input optical signal , the at least one optical resonator being tuned to exhibit a symmetric phase change condition in the output optical signal at normal incidence of the phase modulated input optical signal on a surface of the at least one optical resonator ; an optical-electrical converter configured to detect the intensity modulated output optical signal and to convert the intensity modulated output optical signal into an electrical signal ; and signal processing and control circuitry coupled to the optical resonator assembly and to the optical-electrical converter , the signal processing and control circuitry being configured to receive the electrical signal , to perform symmetric phase change measurements based on the electrical signal , and to provide a control signal based on the symmetric phase change measurements to actuate the steering mechanism to steer the at least one optical resonator to maintain normal incidence of the phase modulated input optical signal on the surface of at least one optical resonator . <EOS>