Single-polarization Optical Fiber Research Articles

Broadband single-polarization optical fiber based on surface plasmon resonance.

We present, to the best of our knowledge, a new scheme of broadband single-polarization optical fiber with high extinction ratio based on surface plasmon resonance (SPR). The double-hole optical fiber with a Ge-doped core is modified by integrating the stacks of conductive and dielectric layers to support SPR. The strong couplings between the guided modes and surface plasmon mode can bring about serious polarization loss of TM mode, while supporting the efficient transmission of TE polarization in broadband. The achievable extinction ratio can be more than 25 dB covering a wide telecom band of 1.17-1.42 µm in short fiber lengths=2.5mm. Meanwhile, the insertion loss of the fiber is less than 0.25 dB. The modified SPR fiber shows promising application in high-quality fiber-integrated polarizers.

Two-core single-polarization optical fiber with a large hollow coated bimetallic layer.

A two-core hollow optical fiber for a polarizer based on surface plasmon resonance (SPR) is proposed and studied by the full-vector finite-element method. The proposed fiber consists of two circular cores, inner cladding, outer cladding, and a large central air hole. The two cores are arranged symmetrically in inner cladding and couple weakly with the air hole. There is no cross talk between cores because they are insulated by the air hole. A nanodimension Ag/Au bimetallic layer can be coated on the inner surface of the central air hole to support SPR. The numerical results show that single polarization of two cores is achieved simultaneously at the wavelength of 1.310 μm, due to strong coupling between the TM mode and the surface plasmon polariton mode. The extinction ratio 40.90 dB with 3 mm length is obtained, and the confinement loss of TE mode is 0.19 dB/cm. Moreover, the resonance wavelength is tunable by varying the refractive index of materials in the central air hole. The scheme is helpful for coupling an all-fiber polarizer with multicore polarization maintaining fibres (PMFs) and makes possible application in in-fiber integrated interferometric sensors while maintaining polarization.

Spin effect on a single-mode single-polarization optical fiber

The spin effect on a single-mode single-polarization optical fiber is investigated theoretically and numerically. To get a practical single elliptically polarized fiber the normalized spin rate must be in the range of 0.2–0.35. A single elliptically polarized fiber with a normalized spin rate around 0.224 is demonstrated. It has a broad band from 1.530 to 1.558 μm, in which the low-leakage elliptically polarized eigenmode loss is kept within 1.2 dB while the high-leakage elliptically polarized eigenmode loss is greater than 20 dB. This fiber can be used as an elliptical polarizer or applied in current sensing.

Propagation characteristics of a single-polarization optical fiber with an elliptic core and triple-clad

This paper gives the propagation characteristics of a single-polarization optical fiber with an elliptic core and triple-clad. This fiber is designed so as to satisfy the zero total dispersion at the operating wavelength of 1.55 μm in the single-polarization region. Thus far, we had studied the n propagation characteristics of single-polarization optical fibers with pits between an elliptic core and the outer cladding (Type-1) and with pits alongside the major axis of an elliptic core (Type-2). In this paper, it is found that a single-polarization optical fiber with an elliptic core and triple-clad has better propagation characteristics compared with Type-1 and Type-2. When the relative index difference between the core and the outer cladding is 0.5%, the main comparison results are as follows: 1) The minimum wavelength sensitivity of the total dispersion can be reduced by approximately 1/3 of those for Type-1 and Type-2, and 2) the single-polarization bandwidth is 2.2 times larger than those of Type-1 and Type-2.

Propagation characteristics of single-polarization optical fibers with the cross section of arbitrary shape

Propagation characteristics of single-polarization optical fibers with the cross section of arbitrary shape

A single-polarization optical fiber of hollow pit type with zero total dispersion at wavelength of 1.55 μm

This paper gives a design method for the single-polarization optical fiber which satisfies simultaneously the wide single-polarization bandwidth, the large modal birefringence, and the zero total dispersion at the wavelength of 1.55 /spl mu/m. As a type of single-polarization fiber, the optical fiber with two hollow circular pits across the core-clad interface is proposed and designed. The normalized power (=/spl Delta/ the power in the core/the total power) in the core is also evaluated for the designed fibers. It was found from the numerical analysis that when the zero total dispersion is satisfied at the wavelength of 1.55 /spl mu/m, the maximum modal birefringence of 1.133/spl times/10/sup -3/ and the maximum single-polarization bandwidth of 100.6 nm are attained for the relative index difference of 1.6%. Then the normalized power in the core is 0.859. >

Polarization cross talk and guided-mode coupling loss with broadband light sources in a single-polarization single-mode optical fiber

Polarization cross talk and guided-mode coupling loss are calculated for a single-polarization single-mode optical fiber, taking into account the effect of light-source bandwidth, Lorentzian-shaped and Gaussian-shaped spectral-density distributions are assumed for the light source. The results show that both polarization cross talk and guided-mode coupling loss reach steady states after a certain propagation distance, although a continuous random polarization coupling caused by external perturbations remains.

Reduction of a polarization-fluctuation-induced error in an optical passive ring-resonator gyro by using a single-polarization optical fiber

The authors evaluate the effect of a single-polarization optical fiber or a fiber polarizer to reduce polarization-fluctuation-induced error in an optical passive ring-resonator gyro. It is clarified that a large output error induced when using an ordinary polarization-maintaining fiber can be suppressed, and a moderate performance gyro can be achieved by using practical parameters of the ring resonator.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Experimental investigation of single-mode single-polarization optical fiber

An experimental study of the polarization properties of single-mode optical fibers of differential polarization-mode attenuation is presented. The output state of polarization was measured at various input polarization orientations and wavelengths. The transition from a two-polarization to a single-polarization regime of operation was investigated. Also, the sensitivity to axial strain was studied at the different wavelengths. The polarization dispersion of the fiber was assessed by measuring the visibility of the polarization interference fringes. Experimental results confirm a previous theoretical study based on Müller-Stokes matrix formalism. The experiments carried out suggest useful applications of such fibers for the development of polarimetric sensors.

Power coupling equations for single-mode, single-polarization optical fibers with effects of leaky modes and broad-band light source

A set of coupled equations for single-mode single-polarization (SMSP) optical fibers applicable to the case with effects of leaky modes and broadband light sources has been derived. The power coupling coefficients are related not only to the birefringence of the SMSP fiber, but also to the leaky mode loss and the spectral linewidth of the light source.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Polarization coupling in single-mode single-polarization optical fibers with a broadband light source

A set of coupled power equations that is applicable to the general case of a quasi-monochromatic light source is derived from the set of coupled amplitude equations for single-mode single polarization (SMSP). The spectral densities of Lorentzian-shaped and Gaussian-shaped distributions are characterized for the quasi-monochromatic light source. Our final results show that the power coupling coefficients are related not only to the birefringence of the SMSP fibers but also to the leaky-mode loss and the spectral half-width of the light source.

Polarization coupling in single-mode single-polarization optical fibers: Power coupling

A set of coupled power equations derived from that of amplitude equations for single-polarization (SMSP) optical fibers has been presented. Our results show that the power coupling coefficients are related not only to the effect of the birefringence of SMSP fibers, but also to the leaky mode loss.

Polarization coupling power in single-mode single-polarization optical fibers

A set of coupled power equations has been derived from a set of coupled amplitude equations for a single-mode single-polarization (SMSP) optical fiber. Our results indicate that the power coupling coefficients are related not only to the birefringence of the SMSP fiber but also to the leaky-mode loss.

A new single-polarization optical fiber

In the single-polarization optical fiber, two isolated stress-applying parts contribute to radiate one of the two orthogonal polarization modes due to the asymmetrical geometric-index effect in addition to a stress-induced birefringence effect without bending the fiber. The loss spectra for x- and y-polarizations and the length dependence of the crosstalk show that the present fiber exhibits single-polarization characteristics.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Polarization coupling in single-mode single-polarization optical fibers

Polarization coupling in single-mode, single-polarization optical fibers is investigated, and a set of coupled-mode equations for single-mode, single-polarization fibers including guided and leaky modes is derived.

Effects of joints on single-mode single-polarization optical fiber links

Single-mode single-polarization fibers appear as an interesting medium for high-capacity long-haul transmission systems. Nevertheless the presence of imperfect joints may lead to undesired effects, such as an excess overall attenuation or a reduction in the signal-to-noise ratio due to intersymbol interference. The exact electromagnetic model of a joint is carried out. A statistical simulation of the behavior of several cascaded fibers separated by joints is presented, showing the importance of some construction and installation parameters.

Reduced pressure collapsing MCVD method for single polarization optical fibers

A simple fabrication method of single polarization optical fibers has been proposed. Core, clad, and jacket layers are deposited in a silica tube. The tube is then collapsed while the inner pressure of the tube is reduced. The core circularity and the jacket ellipticity are controlled by the careful selection of the softening points of core/clad and jacket materials, and the inner pressure. The pressure reduction and the softening points of the constituent glasses play an important role in fabricating single polarization optical fibers.

Composite Dielectric Waveguides with Two Elliptic-Cylinder Boundaries

It is shown that the propagation constants of composite dielectric waveguides with two different elliptic-cylinder boundaries, such as the recent single-polarization optical fibers, are computable by the point-matching method. Numerical results are shown for various combinations of the dielectric constants.

Single-polarization optical fibers: Slab model

Calculations for a simple three-layer slab model show that sufficient anisotropic strain birefringence can be introduced into germanosilicate, phosphosilicate, and borosilicate single-mode fibers to reduce the coupling between orthogonally polarized modes to a level of practical interest for single-mode single-polarization propagation.

Single polarization optical fibers: Exposed cladding technique

A simple method is described for fabricating fibers with large strain birefringence starting with standard MCVD preforms. The method is illustrated using borosilicate fibers. The birefringence and polarization properties are measured in a long fiber and the birefringence is also measured using a fiber slice and polarizing microscope.