Broadband all-fiber optical phase modulator based on photo-thermal effect in a gas-filled hollow-core fiber

Abstract

We report broadband all-fiber optical phase modulation based on the photo-thermal effect in a gas-filled hollow-core fiber. The phase modulation dynamics are studied by multi-physics simulation. A phase modulator is fabricated using a 5.6-cm-long anti-resonant hollow-core fiber with pure acetylene filling. It has a half-wave optical power of 289 mW at 100 kHz and an average insertion loss 0.6 dB over a broad wavelength range from 1450 to 1650 nm. The rise and fall time constants are 3.5 and 3.7 μs, respectively, 2-3 orders of magnitude better than the previously reported microfiber-based photo-thermal phase modulators. The gas-filled hollow-core waveguide configuration is promising for optical phase modulation from ultraviolet to mid-infrared which is challenging to achieve with solid optical fibers.

Mid-infrared optical modulator enabled by photothermal effect

“…Now, writing in Light: Advanced Manufacturing, a sister journal of Light: Science & Applications, Prof. Wei Jin and his team from the Hong Kong Polytechnic University reported an experimental realization of a novel MIR optical modulator enabled by the photothermal effect in an acetylene-filled anti-resonant hollow-core fiber (AR-HCF) 9 . With the assistance of a NIR control beam, the phase of the signal beam is observed to be directly modulated up to 2.2π rad in the MIR (3.35 μm), which extends their previous work on all-fiber phase modulator within C + L bands successfully 10 . And the intensity modulation is verified with a high extinction ratio of 25 dB by employing a Mach-Zehnder interferometer (MZI).…”

Mid-infrared all-optical modulators based on an acetylene-filled hollow-core fiber

“…Furthermore, as control power increases, the gas temperature in the HCF also increases. We believe that the temperature change at high control power is responsible for the nonlinear response 23,28 . Simulated distribution of temperature inside the HCF using COMSOL Multiphysics indicates that the temperature may change up to 100 K in the core center of the HCF.…”

Mid-infrared all-fiber light-induced thermoelastic spectroscopy sensor based on hollow-core anti-resonant fiber

“…In 2022, Ma et al constructed a near-infrared gas sensing system based on a lens set using a hollow-core anti-resonant fiber (HC-ARF) [49] . The special circular structure in HC-ARF has a good suppression effect on mode interference noise in fiber [50] , [51] , [52] . However, the use of lenses has negative effects such as increased system losses and size, and reduced system stability.…”