An optical module includes: a mirror unit having a movable mirror and a fixed mirror; a beam splitter unit; a light incident unit that causes measurement light to be incident to the beam splitter unit; a first light detector that detects interference light of the measurement light; a second light source that emits laser light; a second light detector that detects interference light of the laser light; a first mirror that allows the measurement light to be transmitted therethrough and reflects the laser light; a second mirror that reflects a part of the laser light and allows the remainder of the laser light to be transmitted therethrough; a third mirror that reflects the laser light; and a return light suppressing unit that suppresses the laser light from becoming return light, and is disposed on a side opposite to the second optical device with respect to the second mirror.

A conventional spatial heterodyne spectrometer (SHS) comprises a beam splitter and a pair of diffraction gratings, one in each arm of the SHS. The beam splitter separates an input beam of light into first and second sub-beams for transmission to a respective diffraction grating, and then recombines the diffracted sub-beams for focusing onto a camera. A field widened SHS enables much larger range of input angles of the original beam to be focused onto the camera, so that a broader range of wavelengths may be collected. Increasing the range of wavelengths may be provided by one or more of the following: combining the beam splitter with a field widening prism, making one diffraction grating farther from the beam splitter than the other, and placing a plurality of diffraction gratings in each arm of the SHS.

An optical module 1A includes a mirror unit 2 including a movable mirror 22 and a fixed mirror 16, a beam splitter unit 3, a light incident unit 4, a first light detector 6, a second light source 7, a second light detector 8, a holding unit 130, a first mirror 51, a second mirror 52, and a third mirror 53. The holding unit 130 holds the first light detector 6, the second light detector 8, and the second light source 7 so as to face that same side, and to be aligned in this order. A length of an optical path between the unit 3 and the detector 6 is shorter than a length of an optical path between the unit 3 and the detector 8, and a length of an optical path between the unit 3 and the source 7.

State-of-the-art portable Raman spectrometers use discrete free-space optical components that must be aligned well and that don't tolerate vibrations well. Conversely, the inventive spectrometers are made with monolithic photonic integration to fabricate some or all optical components on one or more planar substrates. Photonic integration enables dense integration of components, eliminates manual alignment and individual component assembly, and yields superior mechanical stability and resistance to shock or vibration. These features make inventive spectrometers especially suitable for use in high-performance portable or wearable sensors. They also yield significant performance advantages, including a large (e.g., 10,000-fold) increase in Raman scattering efficiency resulting from on-chip interaction of the tightly localized optical mode and the analyte and a large enhancement in spectral resolution and sensitivity resulting from the integration of an on-chip Fourier-transform spectrometer.

This disclosure is related to devices, systems, and techniques for precisely measuring a wavelength of an optical signal. For example, a wavemeter system includes processing circuitry, a detector array, a set of optical chips, and a coarse wavelength unit configured to generate a coarse wavelength measurement of the input optical signal. The processing circuitry is configured to select an optical chip from a plurality of optical chips. The detector array is configured to generate a partial interferogram based on the at least the portion of the input optical signal. The processing circuitry is further configured to calculate an optical spectrum of the input optical signal based on the partial interferogram corresponding to the at least the portion of the input optical signal and the calibration matrix and identify, based on the optical spectrum of the input optical signal, the precise wavelength of the input optical signal.

An integrated polarization interferometer includes a polarization beam splitter for separating incident complex waves, a first mirror attached to a first surface of the polarization beam splitter, for reflecting a first polarization transmitted through the polarization beam splitter to the polarization beam splitter, and a second mirror attached to a second surface of the polarization beam splitter, for reflecting a second polarization transmitted through the polarization beam splitter to the polarization beam splitter. Accordingly, it is possible to measure dynamic spectroscopic polarization phenomenon with extremely high robustness disturbances due to an external vibration and the like by using the integrated polarization interferometer, thereby improving measurement repeatability and accuracy of measurement.

A conventional spatial heterodyne spectrometer (SHS) comprises a beam splitter and a pair of diffraction gratings, one in each arm of the SHS. The beam splitter separates an input beam of light into first and second sub-beams for transmission to a respective diffraction grating, and then recombines the diffracted sub-beams for focusing onto a camera. A field widened SHS enables much larger range of input angles of the original beam to be focused onto the camera, so that a broader range of wavelengths may be collected. Increasing the range of wavelengths may be provided by one or more of the following: combining the beam splitter with a field widening prism, making one diffraction grating farther from the beam splitter than the other, and placing a plurality of diffraction gratings in each arm of the SHS.

According to an aspect, there is provided a spectrometer comprising a first and second enclosed volumes. The second enclosed volume is formed by an absorption cell for containing a sample gas. The first enclosed volume of the spectrometer comprises an interferometer with a source of electromagnetic radiation, a first focusing mirror adapted to focus electromagnetic radiation received from the interferometer to the absorption cell, a second focusing mirror adapted to focus electromagnetic radiation received from the absorption cell and a detector adapted to detect electromagnetic radiation focused by the second focusing mirror. Moreover, the spectrometer comprises a main frame plate on which elements in the first enclosed volume are mounted and which is fixed to the absorption cell arranged on an opposing side of the main frame plate.

An optical module includes: a mirror unit having a movable mirror and a fixed mirror; a beam splitter unit; a light incident unit that causes measurement light to be incident to the beam splitter unit; a first light detector that detects interference light of the measurement light; a second light source that emits laser light; a second light detector that detects interference light of the laser light; a first mirror that allows the measurement light to be transmitted therethrough and reflects the laser light; a second mirror that reflects a part of the laser light and allows the remainder of the laser light to be transmitted therethrough; a third mirror that reflects the laser light; and a return light suppressing unit that suppresses the laser light from becoming return light, and is disposed on a side opposite to the second optical device with respect to the second mirror.

A Fourier-transform interferometer includes a phase change plate including a reflective layer configured to reflect a first light that is incident, and a meta surface configured to locally and differently change a phase of the first light that is reflected. The Fourier-transform interferometer further includes a photodetector configured to detect a second light, and a transflective mirror and a mirror configured to transmit a first part of a third light that is incident, to the phase change plate, transmit a remaining part of the third light, to the photodetector, and transmit the first light of which the phase is locally and differently changed, to the photodetector. The photodetector is further configured to detect an interference pattern between the remaining part of the third light and the first light of which the phase is locally and differently changed.