Silicon fourier transform spectrometer and optical spectrum reconstruction method

A silicon Fourier transform spectrometer, comprising:

• a waveguide input coupler (101),
• cascaded optical switches (102),
• unbalanced subwavelength grating (SWG) waveguide pairs (103),
• a germanium silicon detector (104), and
• an external multi-channel power supply,
• wherein the waveguide input coupler (101), the cascaded optical switches (102), the unbalanced subwavelength grating (SWG) waveguide pairs (103), and the germanium silicon detector (104) are prepared on a silicon-on-insulator (SOI) platform;
• the cascaded optical switches (102) comprise N+1 2×2 optical switches, each of the 2×2 optical switches comprises two 3-dB couplers (102a), two balanced waveguides (102b), and one phase shifter (102c), two output terminals of the former 3-dB coupler (102a) are separately connected to one waveguide (102b), one of the balanced waveguides (102b) is integrated with the phase shifter (102c), and the other terminals of the two balanced waveguides (102b) are connected to two input terminals of the latter 3-dB coupler (102a);
• there are N pairs of unbalanced SWG waveguide pairs (103), each pair of unbalanced SWG waveguide pairs comprises two unbalanced SWG waveguides, the two waveguides have different widths and lengths, the optical path difference of an ith unbalanced SWG waveguide pair is OPDi=2i−1OPD1, and the temperature-dependent phase difference shift is 0;
• the output terminal of the waveguide input coupler (101) is connected to one input terminal of the first-stage optical switch of the cascaded optical switches (102), and the two output waveguides of a former-stage optical switch are connected to the two input waveguides of a latter-stage optical switch through the unbalanced SWG waveguide pair (103);
• and the germanium silicon detector (104) adopts a PIN structure, and is connected to one output terminal of the last-stage 2×2 optical switch of the cascaded optical switches (102), where control terminals of the N+1 2×2 optical switches are connected to the external multi-channel power supply.