Integrated High-Speed Wavelength Tracking on a Silicon Chip

A compact wavelength tracking device is integrated into a silicon photonic chip. The device involves an unbalanced Mach-Zehnder interferometer equipped with high-speed PN junction phase shifters operating in carrier-depletion mode. The system uses a modulation-demodulation scheme for reliable wavelength shift extraction on the measured optical signal. The noise standard deviation is $σ = 0.17 pm, featuring a bandwidth of 150 kHz. Absolute wavelength measurements can be achieved within a 2 nm range. The device can also detect relative wavelength shifts in the 1520-1580 nm range. The proposed system finds applications in high-speed photonic sensing such as fast optical fiber Bragg grating sensor interrogation. Signal vibration detection at 42 kHz of a fiber Bragg grating sensor is also demonstrated.