Ming-Jia Li

Quarter wave plate made by cutting straight holey birefringent fiber

Compact samples of quarter wave plate have been fabricated respectively by cutting holey birefringent fiber and conventional birefringent fiber into different length of short sections. The temperature instability and wavelength sensitivity of these samples are analyzed and measured. The influence of fiber length and fiber prototype on the retardation variation is compared. The retardation deviation almost linearly increases with the fiber length of samples. Compared with the sample made of conventional birefringent fiber, the temperature stability of the sample made of holey birefringent fiber is greatly improved by one order, but the wavelength bandwidth needs to be further expanded by optimizing the holey cladding structure.

Structural design for birefringent holey fiber with a beat length insensitive to wavelength

By combination of two defect structures with positive and negative birefringence, we design a holey fiber with a beat length that is less sensitive to wavelength. The influence of different structural parameters on birefringence of holey fiber is calculated by the finite-difference beam propagation method. A stable beat length can be achieved at some given wavelength window by adjusting the parameters. An almost uniform beat length with a greater than 180 nm bandwidth at 1310 and 1550 nm wavelength windows is obtained, which is useful for the design and fabrication of fiber-optic wave plates with a wide band.

Optimal cladding structure of holey fiber designed for broadband fiber-optic wave plate

Two asymmetric structures are combined together in holey cladding of microstructure fiber. One is the rectangular lattice of holes elongated in y-axis. The other is a pair of holes with enlarged diameters near the fiber core oppositely along xaxis. The influence of structural parameters on relation between birefringence with wavelength is calculated. Their interaction at different wavelength can make the beat length insensitive to wavelength. By optimizing the lattice pitches and the holes diameter, 10mm stable beat length with relative bandwidth 12% are obtained in 1310nm and 1550nm bands. This holey fiber is suitable for fabricating wideband fiber-optic wave-plate.

Equivalent Model Parameters of Birefringent Fibre in Longitudinal Magnetic Field

For linear birefringent fibre in magnetic field, compared with the elliptical birefringence model, the analytic expressions of the phase shift and fast axis orientation of the equivalent retarder and the angular rotation of the equivalent rotator have been deduced and discussed.

Stable Quarter Wave Plate Made by Holey Birefringent Fiber

Compact samples of quarter wave plate have been fabricated by cutting holey birefringent fiber into short sections. The temperature instability and wavelength sensitivity of these samples are analyzed and measured. The temperature stability is greatly improved, but the wavelength bandwidth needs further optimization.

Influence of extension lead and input polarization state on performance of quarter wave plate made by increscent-spinning birefringent fiber

The influence of extension lead at both sides and input polarization state on polarization transform performance of increscent-spinning birefringent fibre is calculated and examined. In the extension lead, the output polarization state is fluctuating with period relevant with the max-spin-rate or the beat length of birefringent fiber. It is found, the optimal input polarization state for the best output linear polarization is not the ideal circular polarization but a elliptical polarization related with the maximum spin rate, the optimal input linear polarization orientation is not in line but has a slight divergence angle with the birefringent axes of fiber, and if the input linear polarization is not perfect linear polarization, the output circular polarization would be nonlinearly degraded. These results have advisable meaning for the design, test and evaluation of the quarter wave plate made by the increscent-spinning birefringent fibre.