Theoretical and experimental investigation of light guidance in hollow-core anti-resonant fiber

Abstract

The inherent material imperfections of solid core optical fiber, for example, Kerr nonlinearity, chromatic dispersion, Rayleigh scattering and photodarkening, set fundamental limitations for further improving the performances of fiber-based systems. Hollow-core fiber (HCF) allows the light to be guided in an air core with many unprecedented characteristics, overcoming almost all the shortcomings arising from bulk material. The exploitation of HCF could revolutionize the research fields ranging from ultra-intense pulse delivery, single-cycle pulse generation, nonlinear optics, low latency optical communication, UV light sources, mid-IR gas lasers to biochemical sensing, quantum optics and mid-IR to Terahertz waveguides. Therefore, the investigations into the guidance mechanism and the ultimate limit of HCF have become a hot research topic. In the past two decades, scientists and engineers have fabricated two types of high-performance HCFs with loss figures of 1.7 dB/km and 7.7 dB/km for hollow-core photonic bandgap fiber (HC-PBGF) and hollow-core anti-resonant fiber (HC-ARF) respectively. In comparison with the twenty-years-old HC-PBGF technology, the HC-ARF that recently appeared outperforms the former in terms of broadband transmission and high laser damage threshold together with a quickly-improved loss figure, providing an ideal platform for many more challenging applications. While the guidance mechanism and fabrication technique in HC-PBGF have been well recognized, the HC-ARF still has a lot of room for improvement. At the birth of the first generation of broadband HC-ARF, the guidance mechanism was unclear, the fiber design was far from perfect, the fabrication was immature, and the optical properties were not optimized. In the past five years, we have developed an intuitive and semi-analytical model for the confinement loss of HC-ARF and managed to fabricate high-performance nodeless HC-ARF. We further employ our theoretical model and fabrication technique to well control and design other interesting properties, such as polarization maintenance and bending loss in HC-ARF. For a long time, the anti-resonant theory of light guidance has been regarded as being qualitative, and the leaky-mode-based HC-ARF have been considered to have worse performances than the guided-mode-based HC-PBGF. Our investigations in theory and experiment negative these prejudices, thus paving the way for the booming development of HC-ARF technologies in the near future.

Sensitive carbon monoxide detection based on laser absorption spectroscopy with hollow‐core antiresonant fiber

“…When the light is transmitted to the intersection of core and cladding, the light that accord with the resonance conditions will be transmitted directly from the cladding, while other light that does not accord with the resonance conditions will be reflected back to the core area. 44,45 Therefore, HC-ARF can transmit both light and gas, and light and gas can fully interact inside. Compared with MPC, HC-ARF has the advantages of compact volume, low cost, steady transmission, and simple optical alignment.…”

“…The light guide principle of antiresonant fiber can be explained by the antiresonant reflection principle in planar waveguide. When the light is transmitted to the intersection of core and cladding, the light that accord with the resonance conditions will be transmitted directly from the cladding, while other light that does not accord with the resonance conditions will be reflected back to the core area 44,45 . Therefore, HC‐ARF can transmit both light and gas, and light and gas can fully interact inside.…”

Core-antiresonance-based terahertz cavities and applications [Invited]

“…The antiresonance effect facilitates numerous remarkable applications in the fields of physics, biophotonics, and material science, including the utilization of low-loss waveguides, which span from the ultraviolet [1][2][3][4] to the terahertz (THz) [5] bands, as well as the development of optofluidic chips for gas/liquid atomic spectroscopy [6][7][8][9][10] . Moreover, it enables the creation of multifunctional sensors for various scenarios, such as biochemical sample analysis [11,12] and measurements of physical properties [13,14] like displacement, strain, pressure, and temperature.…”

“…In this work, we provide an overview of our recent investigations into a new antiresonant phenomenon termed core antiresonant reflection (Core-ARR or CARR) [15][16][17] , which yields a broadband THz spectrum with periodic dips at resonant frequencies when THz waves traverse a hollow core tubular structure, such as a single-layer paper tube. Unlike existing principles, e.g., the traditional antiresonant reflection inside hollow optical waveguides (ARROWs) [1][2][3][4][5] , our CARR theory relies solely on characteristics of the tube core (e.g., the inner diameter) instead of the cladding thickness or refractive index, making it fundamentally distinct from established approaches. More importantly, the CARR mechanism enables more kinds of tubular structures to resonate with light waves, thus enhancing the light-matter interactions in corresponding fields, where tubular entities are frequently studied [1][2][3][4][5][6][7][8][9][10] .…”

“…Unlike existing principles, e.g., the traditional antiresonant reflection inside hollow optical waveguides (ARROWs) [1][2][3][4][5] , our CARR theory relies solely on characteristics of the tube core (e.g., the inner diameter) instead of the cladding thickness or refractive index, making it fundamentally distinct from established approaches. More importantly, the CARR mechanism enables more kinds of tubular structures to resonate with light waves, thus enhancing the light-matter interactions in corresponding fields, where tubular entities are frequently studied [1][2][3][4][5][6][7][8][9][10] . Therefore, exciting opportunities are offered by the proposed CARR method for advancements in both fundamental understanding and practical applications.…”