Optical fiber devices with a high extinction ratio based on an anti-resonance mechanism

In this Letter, the proposed optical fiber device enables controllable modulation of the extinction ratio and achieves a high extinction ratio. Based on the single mode fiber-hollow core fiber-single mode fiber structure, we systematically investigate the regulatory effects of hollow core fiber parameters on the transmission spectrum under the anti-resonance mechanism. By means of the anti-resonant reflecting optical waveguides theory, we derive an analytical expression describing the spectral intensity and wavelength at the resonance dip. Both numerical simulations and experimental results confirm that the extinction ratio is closely related to the inner diameter and length of the hollow core fiber. The hollow core fiber with an inner diameter of 20 μm exhibits a relatively high extinction ratio. The extinction ratio of the transmission spectrum based on the anti-resonance mechanism increases gradually with the increase in the length of the hollow core fiber. By means of a simple method of varying the hollow core fiber length, we effectively modulated the extinction ratio within the interval of 2.90-58.07 dB, where the maximum achievable extinction ratio reached 58.07 dB. The relevant conclusions of this study on the extinction ratio of the transmission spectrum in the single mode fiber-hollow core fiber-single mode fiber structure provide important guidance for the design and fabrication of high extinction ratio optical fiber devices, which are expected to be widely applied in the field of high-precision optical fiber sensing and optical communication.