Laser-based sensor

A laser-based sensor, which relates to the technical field of sensing, comprises: a pumping source (01), a common segment (02), a reference segment (03) and a detection segment (04). The common segment (02) is provided with a gain medium (05), and the detection segment (04) is provided with a sensing element (06) capable of causing an optical path difference; the reference segment (03) and the detection segment (04) are connected to the common segment (02) via first and second polarization light splitting units (07, 08); the common segment (02) is provided with an output unit (09), or the reference segment (03) and the detection segment (04) are each provided with an output unit (09); the output unit (09) is connected to a photoelectric detector (11) via a light combination unit (10); and a polarization state rotation unit (12) is also provided between the light combination unit (10) and the output unit (09). The sensor determines the magnitude of a detected physical quantity by measuring the frequency difference due to the heterodyne interference caused by two paths of laser light having different frequencies; the laser frequencies are extremely sensitive to the optical path change of resonant cavities, and therefore the detection sensitivity and precision are relatively high; and in addition, the two resonant cavities of the sensor share an optical path, such that the anti-jamming capability is strong, and the laser-based sensor is applicable to measuring very tiny changes in various physical quantities.