Theoretical proposal of a low-loss wide-bandwidth silicon photonic crystal fiber for supporting 30 orbital angular momentum modes

Abstract

We propose a novel four-ring hollow-core silicon photonic crystal fiber (PCF), and we systematically and theoretically investigate the properties of their vector modes. Our PCF can stably support 30 OAM states from the wavelength of 1.5 μm to 2.4 μm, with a large effective refractive index separation of above 1×10−4. The confinement loss is less than 1×10−9 dB/m at the wavelength of 1.55 μm, and the average confinement loss is less than 1×10−8 dB/m from the wavelength of 1.2 μm to 2.4 μm. Moreover, the curve of the dispersion tends to flatten as the wavelength increases. In addition, we comparably investigate PCFs with different hole spacing. This kind of fiber structure will be a potential candidate for high-capacity optical fiber communications and OAM sensing applications using fibers.

A Photonic crystal fiber with large effective refractive index separation and low dispersion

“…Fig 6 demonstrates that the Δn eff between each eigenmode is above 1×10 −4 , and most values for the Δn eff between the HE m+1,1 and EH m-1,1 eigenmode sets are greater than 10 −3 ; this result means that near-degeneracy into the LP m,1 modes will hardly occur and mode crosstalk will almost disappear, remarkably improving the reliability of information transmission. Additionally, Fig 7 suggests a tremendous advance in preventing modal coupling and near-degeneracy compared with our previous work [7] and that of our peers [24,26]. The CL for eigenmodes guided in the proposed fiber can be calculated through [7]:…”

“…Additionally, Fig 7 suggests a tremendous advance in preventing modal coupling and near-degeneracy compared with our previous work [7] and that of our peers [24,26]. The CL for eigenmodes guided in the proposed fiber can be calculated through [7]:…”

“…Orbital angular momentum (OAM) beams have attracted great attention [1][2][3][4][5][6][7][8][9] since Allen et al experimentally verified their existence in 1992 [1]. In the paraxial approximation, an OAM beam is characterized by a helical phase front of exp(jlφ), where l represents the topological charge value, and φ represents the azimuthal angle [7,10]. As one of the most fundamental physical quantities in classical and quantum electrodynamics, OAM beams have been applied in many fields, such as optical communications [4], quantum information processing [5], and optical manipulation [6,7].…”

“…In the paraxial approximation, an OAM beam is characterized by a helical phase front of exp(jlφ), where l represents the topological charge value, and φ represents the azimuthal angle [7,10]. As one of the most fundamental physical quantities in classical and quantum electrodynamics, OAM beams have been applied in many fields, such as optical communications [4], quantum information processing [5], and optical manipulation [6,7]. These beams also have some unique characteristics.…”

“…W. Tian et al designed a C-PCF which can support 26 OAM modes in 2016 [24]. X. Xu proposed a circular PCF based on silicon to transmit 30 OAM modes [7]. In addition, Z.…”