All-Optical Tunable Fiber Filter With Dual Graphene Films Enabled by a Fiber Open Microcavity

Short Carbon Nanotube Nano-Film-Based Polymer/SiO2 Hybrid Waveguide Micro-Ring Filter

“…The free spectral range (FSR) of the filter can be expressed as 22 (6) where N g is the effective group RI of the waveguide, and it can be given by (7) The Q of the micro-ring resonator is an index to measure the ratio of energy storage and loss of a micro-ring resonator. Generally, the higher the Q of a micro-ring resonator, the higher its frequency stability, which can be written as 23 (8) where is the 3 dB bandwidth of the resonant wavelength and can be observed in the transmission spectrum; β is the amplitude loss factor of the light field traveling along the micro-ring for one cycle; and t 1 and t 2 are the self-coupling factors of the coupling region. It can be seen from the above formulas that Q is related to the radius of the micro-ring resonator.…”

“…In 2021, our group proposed a dual graphene films-enabled all-optical tunable filter with a wavelength-tunable efficiency of −0.104 nm/mW at 980 nm pump power. 8 In the same year, our group proposed a broadband all-optical tunable filter based on graphene/epoxy resin composite material, whose wavelength tuning range and tuning efficiency were 25.54 nm and −832 pm/mW, 9 respectively. It is worth noting that although the above two filters have high tuning efficiency, their volume and loss are relatively large, and they cannot be made into chip-level filters.…”

“…But the above two tunable filters have low tuning efficiency, which will be limited in practical applications. In 2021, our group proposed a dual graphene films-enabled all-optical tunable filter with a wavelength-tunable efficiency of −0.104 nm/mW at 980 nm pump power . In the same year, our group proposed a broadband all-optical tunable filter based on graphene/epoxy resin composite material, whose wavelength tuning range and tuning efficiency were 25.54 nm and −832 pm/mW, respectively.…”