High-Resolution Detection of Wavelength Shift Induced by an Erbium-Doped Fiber Bragg Grating

We analyze theoretically and verify experimentally a high-resolution and low-cost method to detect wavelength shift induced by an Erbium-doped fiber Bragg grating. A pi-phase-shifted fiber Bragg grating on a temperature controlling setup is employed to achieve tunable single-sideband modulation. To further enhance measurement stability and diminish operational complexity, an asymmetric phase-shifted fiber Bragg grating is developed to reflect wide single-sideband modulation signals and avoid the tuning of the optical carrier wavelength. Through the using of microwave photonics technique, the wavelength shift of the Erbium-doped fiber Bragg grating induced by laser pumping is mapped onto the amplitude variation of the beat signal. The results indicate 1 GHz frequency shift, corresponding to 0.008 nm wavelength shift in the 1550 nm band, is able to be detected. The resolution can be further improved by using a more accurate temperature controlling system. Furthermore, our approach offers an alternative method to detect weak temperature and strain changes on chips or other sensing systems with high accuracy.