Surface plasmon resonance sensors and method for detecting samples using the same

An optical sensing device comprising:

• a source unit, comprising:
• a source emitting a beam of light containing p-polarization and s-polarization components, and
• a phase modulator modulating a phase retardation between the p-polarization and s-polarization components;
• a reference unit, configured to receive a first part of the light, thereby providing a reference signal indicating the modulated phase retardation;
• a SPR sensing unit, configured to receive a second part of the light, thereby inducing a phase retardation change between the p-polarization and s-polarization components due to SPR associated with a sample;
• a probe unit, configured to receive the light passing the SPR sensing unit thereby providing a probe signal indicating the phase retardation change induced by the SPR sensing unit;
• and
• a detection unit, coupled between the reference unit and the probe unit to detect biological, biochemical, or chemical characteristics of the sample by comparing the reference signal with the probe signal.