Optoelectronics Letters, Volume. 18, Issue 10, 577(2022)
Ultra-broadband optical filter based on chirped long-period fiber grating using leaky mode coupling
An ultra-broadband optical filter was proposed and demonstrated based on leaky mode coupling in a coated chirped long-period fiber grating (CLPFG). The CLPFG was coated with a material whose refractive index (RI) was higher than that of the fiber cladding, enabling the coupling of the core mode to leaky modes, to achieve a desired coupling efficiency. Complex coupled-mode theory was used to investigate the power evolution of the core mode that resulted from the coupling. From this, the conditions in which the core mode power attenuates the most rapidly were identified. In addition, phase matching turning point (PMTP) was used in the design, to overcome the conflict between the range of grating period change and the grating length in the CLPFG. Finally, an optimized CLPFG-based filter with a length of 3.5 cm was obtained, which has a symmetrical attenuation band with an operating bandwidth over 300 nm. Within the operating bandwidth, the flatness is less than 2.5 dB and the transmittance is lower than 0.1%.
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XUE Linlin, Bras Samuel Malumba Timoteo, QIU Weiwei, WANG Zhongpeng. Ultra-broadband optical filter based on chirped long-period fiber grating using leaky mode coupling[J]. Optoelectronics Letters, 2022, 18(10): 577
Received: Mar. 19, 2022
Accepted: Jun. 7, 2022
Published Online: Jan. 20, 2023
The Author Email: Linlin XUE (119029@zust.edu.cn)