Nodeless hollow-core fiber for the visible spectral range

Abstract

We report on a hollow-core fiber (HCF) whose fundamental transmission band covers almost the whole visible spectral window, starting at 440 nm. This HCF, in the form of a nodeless structure (NL-HCF), exhibits unprecedented optical performance in terms of low transmission attenuation of 80 dB/km at 532 nm, a broad transmission bandwidth from 440 to 1200 nm, a low bending loss of 0.2 dB/m at 532 nm under 8 cm bending radius, and single-mode profile. When launched to high-power picosecond laser systems at 532 nm, the fiber, exposed to ambient air, could easily deliver an 80 ps, 58 MHz, 32 W average power laser pulse with no damage and a 20 ps, 1 kHz high-energy laser pulse with a damage threshold in excess of 144 μJ at a fiber output. A proof-of-concept experiment on Raman spectroscopy in ambient air shows the significance of this broadband visible guiding HCF for interdisciplinary applications in nonlinear optics, ultrafast optics, lasers, spectroscopy, biophotonics, material processing, etc.

Confinement loss in hollow-core negative curvature fiber: A multi-layered model

“…The glass wall thicknesses of both structures are 0.24m, and the inter-tube gaps in the NCF are 0.8m wide. This is close to a practically realizable NCF with current state-of-art fabrication technique [3][4][5][6][7]. For the NCF, in order to retrieve the complex effective indices, n eff , of the fundamental core modes, we perform numerical simulation based on a finite-element mode solver (Comsol Multiphysics).…”

“…In this practical case, the minimum simulated CL of the single-ring NCF becomes 7.5dB/km at 700nm. The reported fabricated fibers show similar loss levels [3][4][5][6][7]. Based on above analysis, how to prevent the outermost air layer to be in the resonant leakage region will be a crucial challenge [47].…”

“…After 20 years development of hollow-core photonic crystal fiber (HC-PCF) [1,2], a type of fiber structure as simple as a ring of 6-8 untouched thin tubes surrounding the hollow core [3][4][5][6][7] has very recently emerged as the cutting-edge research area in fiber optics. This type of hollow-core fiber (HCF), referred to as hollow-core negative curvature fiber (NCF) in this paper (or more broadly named hollow-core anti-resonant fiber (ARF)) shows similar level of transmission loss and single modeness with the maturely developed hollow-core photonic-bandgap fiber (PBGF) and outperforms the PBGF in terms of broadband light guidance and high laser damage threshold.…”

Measurement of the Verdet Constant of Polarization-Maintaining Air-Core Photonic Bandgap Fiber

“…New PCFs emerge constantly according to different applications, such as the recent composite PCFs [3,4], nodeless air-core PCFs [5], and so on. Among those fibers, air-core photonic bandgap fiber (PBF) offers a radically new method for solving the problem of environment (including magnetic field) adaptation, because the PBF causes light to propagate in air that exhibits much lower sensitivity to magnetic fields than conventional SiO 2 [6].…”

Coherent optical modulation of graphene based on coherent population oscillation

“…We also report the pulse duration regulation through tuning the effective bandwidth of graphenecovered-chirped fiber Bragg grating by changing refractive index of graphene [17]. Nevertheless, this process is incoherent, which is mainly originated from the carrier-phonon scattering process of graphene [18]. Therefore, the strong power of pump laser makes the incoherent optical modulation and thermal-optical effects low efficient.…”