Ring-Core Photonic Crystal Fiber of Terahertz Orbital Angular Momentum Modes with Excellence Guiding Properties in Optical Fiber Communication

• Main Authors: Fahad Ahmed Al-Zahrani, Md. Anowar Kabir
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Photonics
• Subjects: orbital angular momentum (OAM); mode division multiplexing (MDM); space division multiplexing (SDM); ring-core photonic crystal fiber (RC-PCF); optical communication; mode separation
• Online Access: https://www.mdpi.com/2304-6732/8/4/122

The orbital angular momentum (OAM) of light is used for increasing the optical communication capacity in the mode division multiplexing (MDM) technique. A novel and simple structure of ring-core photonic crystal fiber (RC-PCF) is proposed in this paper. The ring core is doped by the Schott sulfur difluoride material and the cladding region is composed of fused silica with one layer of well-patterned air-holes. The guiding of Terahertz (THz) OAM beams with 58 OAM modes over 0.70 THz (0.20 THz–0.90 THz) frequency is supported by this proposed RC-PCF. The OAM modes are well-separated for their large refractive index difference above <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup></semantics></math></inline-formula>. The dispersion profile of each mode is varied in the range of 0.23–7.77 ps/THz/cm. The ultra-low confinement loss around <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mn>10</mn><mrow><mo>−</mo><mn>9</mn></mrow></msup></semantics></math></inline-formula> dB/cm and better mode purity up to 0.932 is achieved by this RC-PCF. For these good properties, the proposed fiber is a promising candidate to be applied in the THz OAM transmission systems with high feasibility and high capacity.