JPH01134403A - Polarization maintaining optical fiber - Google Patents

Abstract

PURPOSE:To enable easy checking of a main axial direction and the easy discrimination of the kinds of fibers by coloring stress imparting parts. CONSTITUTION:This polarization maintaining optical fiber has 1.3mum wavelength, 10mum diameter of a core 1, 125mum diameter of a clad 3, 35mum outside diameter of the stress imparted parts 2, and 30mum distance between the stress imparted parts and the core 1. The stress imparted parts 2 are colored black. The positions of the stress imparted parts 2 are easily checkable even if antireflection glass is stuck to the end face. The stress imparted parts 2 are variously colored according to the kinds of the fibers not only to facilitate the checking of the main axial direction A. The kind of the polarization maintaining optical fiber is thereby easily discriminated and the main axial direction is checked.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a source fiber used for an optical communication transmission line or a fiber sensor, and particularly to a polarization-maintaining optical fiber.

(Prior Art) In recent years, polarization-maintaining optical fibers are expected to find wide use as transmission lines for coherent source communications, as well as for applications in fiber sensors and fiber-shaped components. Among polarization-maintaining optical fibers suitable for such applications, stress-applied polarization-maintaining fibers are attracting particular attention because of their low loss and excellent low crosstalk properties.

The main stress-applied polarization-maintaining optical fibers are shown in Figure 2 (
Shown in a) to (C). Figure 2 (a) is a panda (PAN).
Cross-section of polarization-maintaining optical fiber of type DA ), Figure 2(b)
is a cross section of a BOW-TIE type polarization maintaining optical fiber, and FIG. 2(c) is a cross section of an elliptical clad type polarization maintaining optical fiber. In FIGS. 2(a) to (C),
1 is a shear, 2 is a stress applying portion, 3 is a beam 2, and 3' is an internal cladding.

The stress-applying type polarization-maintaining optical fiber has a structure in which the direction in which stress can be applied to the core 1 is limited, so the main axis direction of the polarization-maintaining optical fiber is It can be confirmed from the direction or stress application position.

Connection of polarization-maintaining optical fiber to a fusion-spliced one-way connector,
Alternatively, in combination with elements with polarization characteristics, in order to maintain high polarization maintaining characteristics, it is necessary to align the principal axes of the connected fibers or the principal axes A of the optical elements to be combined. . Ninth, it is necessary to confirm the main axis direction A in advance.

Conventionally, the stress-applying portion 2 of a polarization-maintaining optical fiber is 8 i
02 glass is often doped with B2O3 or the like. In this case, the applied portion 2 is the cladding 3 (see Fig. 2).
In C), it is transparent like the outer cladding 3').

(Problem to be Solved by the Invention) In the conventional polarization-maintaining optical fiber described above, the stress-applying portion has the same transparent color as the cladding, so the principal axis direction can be confirmed from the positional relationship between the stress-applying portion and the core. The drawback was that it was not easy to do so.

In particular, attaching antireflection glass or filter glass to the end face of a polarization-maintaining optical fiber has the disadvantage that in the following cases, the original reflection of the %m plane is extremely small, making it difficult to confirm the principal axis direction. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to provide a polarization-maintaining optical fiber which eliminates the above-mentioned drawbacks by coloring the stress-applying portion and is configured so that the entire main axis direction can be easily confirmed.

(Means for resolving the problem t-S) The polarization-maintaining optical fiber according to the present invention has a circular cross-section and can apply stress to the core for transmitting an optical signal and the side surface of the core.

It is constructed by comprising a pair of stress-applying portions each having a circular cross section, and a colored cladding formed to have a circular cross-section and surrounding the core and the stress-applying portion.

(Example) Next, one embodiment of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a panda-shaped polarization-maintaining optical fiber according to the present invention.

In FIG. 1, %l is the core, 2 is the stress applying portion, and 3 is the cladding.

The polarization maintaining optical fiber has a wavelength of 1.3 μm, a diameter of the core 1 of 10 μm, a diameter of the cladding 3 of 125 μm, an outer diameter of the stress applying portion 2 of 35 μm, and a distance between the stress applying portion 2 and =71 of 30 μm. The stress-applying portion 2 is colored black so that the position of the stress-applying portion 2 can be easily confirmed even when anti-reflection glass is attached to the end face.

Furthermore, in addition to making it easy to confirm the principal axis direction A, it is also possible to distinguish the types of polarization-maintaining optical fibers by coloring the stress-applying portions 2 in various colors depending on the type of fiber.

(Effects of the Invention) As explained above, the present invention has the effect that the principal axis direction can be easily confirmed by coloring the stress-applying portion, and furthermore, the type of fiber can be easily distinguished. be.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a panda-shaped polarization-maintaining optical fiber according to the present invention. FIGS. 2(a) to 2(e) are cross-sectional views showing examples of various polarization-maintaining optical fibers according to the prior art. l...Core 2...Stress applying portion 3, 3'-...Crat. Patent applicant: NEC Corporation

Claims (1)

[Claims] a core having a circular cross section and for transmitting an optical signal; a pair of stress applying portions capable of applying stress to the side surfaces of the core and having circular cross sections; the core and the stress applying portion; A polarization-maintaining optical fiber comprising a colored cladding having a circular cross section.