Wenliang Lu

Ultrabroadband polarization splitter based on three-core photonic crystal fibers

An ultrabroadband polarization splitter based on three-core photonic crystal fiber (PCF) is proposed. Two fluorine-doped cores and an elliptical modulation core are introduced to achieve an excellent performance and an ultrawide bandwidth. Numerical results demonstrate that the polarization splitter based on three-core PCF has an extinction ratio as low as -20 dB bandwidth as great as 400 nm covering almost all communication bands (O, E, S, C, and L bands). Its Gaussian-like mode-field distributions and suitable effective mode areas make it highly compatible with the standard single-mode fibers. Due to using a uniform size of circular air holes and only one elliptical central air hole, the difficulty of fabrication can be decreased to some extent.

Bending Orientation Insensitive Large Mode Area Photonic Crystal Fiber With Triangular Core

In view of the feasibility of fabrication and application, a bending orientation insensitive large mode area photonic crystal fiber with triangular core is proposed. This fiber structure breaks the limit of bend orientation angle and realizes single mode operation under any bending orientation angle at the bending radius of 30 cm. The mode field area of the fundamental mode at the wavelength of 1.064 μm achieves 1386 μm2 at the straight state and 1154 μm2 at a bending radius of 30 cm, respectively. The decrement of the mode field area at the bent state is only 16.85% compared to that at the straight state. The large mode area at the bent state, small decrement of the mode field area, and low sensitivity of bending orientation make the fiber of great potential in compact high power fiber lasers.

Bend-resistant large-mode-area photonic crystal fiber with a triangular-core

In view of its feasibility for fabrication and application, a bend-resistant large-mode-area photonic crystal fiber with a triangular core is proposed. In our design, the fiber proposes a solution to the issue of bend distortion. The mode field area of the fundamental mode at the wavelength of 1.064 μm achieves 930 μm² at the straight state and 815 μm² at a bending radius of 30 cm, respectively. The decrement of the mode field area at the bend state is only 12.473% compared to the straight state. Furthermore, when the fiber is bent with a bending radius of 30 cm, numerical results demonstrate that the fiber conforms to single-mode operation conditions and the bending orientation angle can be extended to ±55°. A large mode area at bent state and low sensitivity of bending orientation make the fiber of great potential in high-power fiber lasers.

Bend Resistant Large Mode Area Fiber With Multi-Trench in the Core

A bend resistant large mode area fiber with multitrench in the core is proposed. Four layers of trenches with high refractive index are introduced to modulate the mode field distribution. Low refractive index trenches in traditional designs are replaced with pure silica trenches to reduce the difficulty of manufacture. Meanwhile, the core region with a refractive index higher than pure silica cladding conforms to the practical requirement for active fibers. Numerical investigations show that single mode operation with a mode field area of 1100 μm2 is achieved at a bend radius of 15 cm. This design shows the potential of mode field scaling for multitrench fibers and makes a contribution to compact high power fiber lasers.

Investigation of Flexible Low-Loss Hollow-Core Fibres With Tube-Lattice Cladding for Terahertz Radiation

Through the use of low absorption Zeonex polymer, three flexible low-loss hollow-core tube-lattice fibres were successfully fabricated for Terahertz radiation, spanning the range 0.1-1.5 THz. The loss and dispersion of these fibres were investigated through both experimental characterization and simulations. The fibres had characteristic transmission windows determined by the thickness of the tubes in the cladding, and both loss and dispersion were shown to be low in the middle of these as expected. The experimental results were in good accord with simulations. Losses of 5 dB/m were shown for low frequencies, whilst at high frequencies, losses of 0.1-1 dB/m were estimated, making these amongst the lowest losses reported for this frequency range.

Demonstration of low-loss flexible fiber with Zeonex tube-lattice cladding for Terahertz transmission

A Zeonex hollow-core terahertz fiber was developed successfully. The lowest loss is 1dB/m at the frequency below 1THz, which is much lower than THz fibers reported. The loss is still below 5dB/m when its bent.

Rectangle Lattice Large Mode Area Photonic Crystal Fiber for 2

A rectangle lattice silica-host photonic crystal fiber with large mode area (LMA) is successfully fabricated for the first time. The introduction of rectangle lattice contributes to distinct leakage of second order modes and two large air holes provide an effective solution to suppress bend distortion. Numerical results demonstrate that a large mode field area (MFA) of 2500 μm2 is achieved at the wavelength of 2 μm when the fiber is straight. While the fiber is bent to a radius of 30 cm, it confirms to single-mode (SM) operation conditions and the decrements of MFA at x polarization and y polarization are just 4.3% and 5%. Within a bend orientation angle of ± 10° and a wide wavelength range from 1.8 μm to 2.4 μm, the fiber can operate under single-mode (SM) conditions with low bend loss. LMA, SM operation, and small bend distortion make this fiber of great potential in developing 2 μm compact high-power fiber lasers.