Adjustable single-channel time-domain sampling filter, spectrometer, and detection method

An adjustable single-channel time-domain sampling filter, which, when in use, is configured in an on-chip computationally reconstructed spectrometer, comprises N stages of cascaded asymmetric interference units, where N≥3;

• the asymmetric interference unit comprises:
• a first waveguide splitting element, arranged at an input end, for splitting an input light into two paths for output according to a preset splitting ratio;
• two interference arms, respectively receiving light output by the two paths of the first waveguide splitting element;
• the two interference arms have different arm lengths;
• and,
• a second waveguide splitting element, for combining output light of the two interference arms to induce optical interference;
• wherein at least three asymmetric interference units are provided with phase modulators on their interference arms;
• in two consecutive cascaded stages of asymmetric interference units, the output light of the second waveguide splitting element in a previous stage serves as the input light of the first waveguide splitting element in a subsequent stage;
• when in use, the adjustable single-channel time-domain sampling filter generates optical channels with different spectral responses in a time sequence by tuning the phase modulators located in different cascaded asymmetric interference units.