Polarization sensitive optical side leakage radiometry for distributed characterization of anti-resonant hollow-core fibers.

A novel technique referred to as optical side leakage radiometry is proposed and experimentally demonstrated for non-destructive and distributed characterization of anti-resonant hollow-core optical fibers with high spatial resolution. Through in-depth analysis of the leakage light collection, we discover a unique polarization dependence, which is validated by our experiment. By leveraging this effect and employing Fourier filtering, this method enables accurate quantification of propagation attenuations for fundamental and higher order modes (with the uncertainty of <1 dB/km), identification of localized defects (with the resolution of ∼5 cm), and measurement of ultra-low spectral phase birefringence (at the level of 10) in two in-house-fabricated nested antiresonant nodeless hollow-core fibers.

Selectively gas-filled anti-resonant hollow-core fibers for broadband high-purity LP mode guidance.

An anti-resonant hollow-core fiber capable of propagating the LP mode with high purity and over a wide wavelength range is proposed and demonstrated. The suppression of the fundamental mode relies on the resonant coupling with specific gas selectively filled into the cladding tubes. After a length of 2.

Accurate modeling and measurement of pressure-induced group velocity dispersion variations in anti-resonant hollow-core fibers.

Precise control of group velocity dispersion (GVD) by pressure in a gas-filled hollow-core fiber (HCF) is of essential importance for many gas-based nonlinear optical applications. To accurately calculate the pressure-induced dispersion variations (∂β/∂p) in anti-resonant types of HCF, an analytical model combining the contribution of the gas material, capillary waveguide, and cladding resonances is developed, with an insightful physical picture. Broadband (∼1000 nm) GVD measurements in a single-shot manner realize accuracy and precision as low as 0.

Birefringent, low loss, and broadband semi-tube anti-resonant hollow-core fiber.

We report on the design, fabrication, and characterization of a low-loss birefringent semi-tube anti-resonant hollow-core fiber (AR-HCF). By optimizing the structure design and the stack-and-draw fabrication technique, a transmission loss of 4.8 dB/km at 1522 nm, a <10 dB/km bandwidth of 154 nm, and a phase birefringence of 1.

Air flowing induced thermo-optic effect for thermal sensitivity reduction in anti-resonant hollow core fibers.

The signal propagation delay through an optical fiber changes with environmental temperature, imposing a fundamental limit on performances in many fiber-optic applications. It has been shown that the thermal coefficient of delay (TCD) in hollow core fibers (HCFs) can be 20 times lower than in standard single-mode fibers (SSMFs). To further reduce TCD over a broad wavelength range at room temperature, so that to enrich fiber-optic applications in time- synchronization scenarios, the thermal expansion effect of silica glass must be compensated for.

High extinction ratio and low backreflection polarization maintaining hollow-core to solid-core fiber interconnection.

We develop a hybrid cold/heat two-step splicing approach for low loss, low backreflection, and high polarization extinction ratio (PER) hollow-core to solid-core fiber interconnection. The employed hollow-core fiber (HCF) is our recently developed high-birefringence polarization-maintaining hollow-core fiber (PM-HCF) with a PER value of ∼30 dB, and the solid-core fiber (SCF) is a commercial Panda polarization-maintaining fiber (Panda fiber). Simultaneous low backreflection (<-35 dB), low insertion loss (IL) (∼0.