Ultrahigh birefringence of elliptic core fibers with irregular air holes

Abstract

We have investigated experimentally and theoretically the birefringence of the elliptic core fiber with irregular air holes. The wavelength dependence of the beat length and the birefringence was measured by the wavelength scanning method. The fiber exhibits ultrahigh birefringence of 1.12 ϫ 10 −2 at 1550 nm. We also calculated the modal birefringence of the fundamental modes in the fiber by using the plane wave expansion method. The calculated birefringence is in excellent agreement with the measured one.

Ultrahigh-birefringent squeezed lattice photonic crystal fiber with rotated elliptical air holes

“…Photonic crystal fibers (PCFs), optical fibers with a core surrounded by an array of air holes extending down the fiber length, have been shown to sometimes be much more birefringent than conventional fibers owing to a more complex geometry and a higher difference in the refractive index. Although there are some experimental realizations of different types of highly birefringent PCFs (Hi-Bi PCFs), most of them are based in deformations with a low degree of control during the fabrications process [1][2][3] or contain various elements around the core [4,5].…”

Hybrid square-lattice photonic crystal fiber

“…Recently, due to the large index contrast of photonic crystal fibers (PCFs) compared to the conventional fiber, highly birefringent (HB) PCFs have been reported by breaking the circular symmetry implementing asymmetric defect structures such as dissimilar air hole diameters along the two orthogonal axes [1][2], asymmetric core design [3][4] and designing an air hole lattice or a microstructure lattice with inherent anisotropic properties such as the elliptical-hole PCF [5][6], and squeezed hexagonal-lattice PCFs [7][8]. Modal birefringence in these HB PCFs has been predicted to have values an order magnitude of 10 -3 or 10 -2 higher than that of the conventional HB fibers (10 -4 ) [9].…”

Hybrid Square-Lattice Photonic Crystal Fiber with Broadband Single-Mode Operation, High Birefringence, and Normal Dispersion

“…The birefringence of these HB-PCFs ranges from 10 -3 to 10 to two orders of magnitude higher than in conventional HB fibers [15]. Due to the difficulty of fabricating noncircular air holes, most HB-PCFs have been extensively designed with only circular air holes by breaking the cylindrical symmetry of the fiber [6,[9][10][11]. In previous HB-PCFs, high birefringence could be achieved easily due to the greatly enhanced refractive-index contrast.…”

“…In recent years photonic crystal fibers (PCFs) have been widely investigated due to their unique optical properties such as high birefringence, anomalous dispersion, and single-mode operation [4][5][6][7][8], which cannot be achieved in conventional optical fibers. Due to their greatly enhanced index contrast, PCFs can easily achieve very high birefringence (HB), and various HB-PCF designs have been reported with asymmetric defect structures such as dissimilar air holes along the two orthogonal axes [6,9], asymmetric defect cores [10][11], elliptical-hole PCFs (EPCFs) [12], and squeezed-lattice PCFs [13][14]. The birefringence of these HB-PCFs ranges from 10 -3 to 10 to two orders of magnitude higher than in conventional HB fibers [15].…”