JPS61146734A - Germanium oxide series optical fiber - Google Patents

Abstract

PURPOSE:To protect the titled optical fiber from the moisture content contained in air and to increase the durability thereof by forming a silica glass series weathering resistant glass layer which has the refractive index equal or more to a cladding on the outside periphery of the cladding of the germanium oxide series optical fiber. CONSTITUTION:A silica glass series weathering resistant glass layer 3 which has the refractive index equal or more to the refractive index of a cladding 2 is formed on the outside periphery of the cladding 2 of optical fiber which has a core 1 consisting of the germanium oxide series glass and the cladding 2 and furthermore a coated layer 4 is formed thereon to make the aimed germanium oxide series optical fiber. As the silica series glass layer 3, the following glass having >=1.58 refractive index is preferable wherein <=90% SiO2 is contained as an essential component and Al, Ca, Pb and B or the like are added thereto and the thermal characteristics such as the thermal expansion coefficient and the softening point of glass are matched with the germanium oxide series glass.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical fiber whose core and cladding are made of germanium oxide.

(Prior Art) Germanium oxide-based optical fibers are attracting attention as optical fibers for nonlinear optics that have a light amplification effect.

The important points for this type of optical fiber are high purity, workability, and durability, but weather resistance is somewhat difficult. The cladding etc. become cloudy and the strength deteriorates considerably.

Of course, germanium oxide optical fibers are also coated with silicone-based resins, but in the case of this organic resin,
In the long run, the above measures are not sufficient because moisture in the air will pass through.

In addition, for germanium oxide optical fibers for non-wire optics, it is said that it is better to use single-mode optical fibers with a small core diameter to increase the optical power density, but at present, as the core diameter becomes smaller, the outer diameter of the cladding also increases. The thickness is set to about 80 μm, which makes connection work and general handling inconvenient.

Another reason for reducing the outer diameter is the desire to reduce the high cost of germanium through material savings, thereby lowering the cost of the optical fiber.

(Problems to be Solved by the Invention) The present invention attempts to solve the above-mentioned problems of the conventional example, such as lack of weather resistance and insufficient outer diameter, without causing deterioration of characteristics or increase in cost. It is.

(Means for Solving the Problem) The present invention provides an optical fiber in which the core and cladding are made of germanium oxide. It is characterized by the formation of layers.

(Function) In the case of the optical fiber of the present invention, since a weather-resistant glass layer is formed on the outer periphery of the cladding, the optical fiber can be protected through the weather-resistant glass layer, and its outer diameter can also be increased. Because the glass layer is made of silica glass, which is cheaper than germanium oxide, there is a lack of weather resistance,
There is no cost increase to solve problems such as insufficient outer diameter.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In the figure, 1 is the core, 2 is the cladding, and 3 is the cladding 2
A weather-resistant glass layer formed on the outer periphery of the glass layer 3, 4 is the glass layer 3
This is a plastic covering layer formed around the outer periphery of the

The core of the above! , cladding 2 is germanium oxide-based, and consists of seven components such as the main component GeO2, a component 5b203 that sets the refractive index, and an alkali element (glass stabilizing component), but core l contains more 5b203 than cladding 2, and the cladding The refractive index is higher than that of 2.

In addition to having weather resistance, the glass layer 3 has a refractive index that is equal to or higher than the refractive index (1,58) of the cladding 2, and has thermal properties such as a coefficient of thermal expansion, a glass transition point, and a glass softening point that are similar to those of germanium oxide. It is required to match with glass.

The glass layer 3 that satisfies these requirements is desirably composed mainly of SiO2, to which one or more additives such as aluminum, calcium, lead, boron, barium, alkali elements, and other additives are added.

However, the content of 5102 in the glass layer 3 is from 0 to
A range of 8 oz is suitable; if this exceeds 11 oz, the above properties are impaired.

A thermosetting or ultraviolet curable resin is used as the coating layer 4, and a specific example thereof is a silicone type resin.

More specific examples of the present invention will be described below.

Ba, Zn, Ca, Si, A1. Sb, M
When an oxide glass pipe was prepared by adding La or Y to g, the linear expansion coefficient of this glass pipe was (40
~70) XIO', working temperature 800~1000
℃, and the refractive index was 1.815.

This is very close to the properties required above.

This glass pipe and a ready-made germanium oxide optical fiber base material are spun using the rod-in-tube method to form a core.
An optical fiber having a diameter of 80 layers, a cladding 2 having a diameter of 80 layers, and a glass layer 3 having a thickness of 351 L was prepared, and a coating layer 4 made of thermosetting silicone resin was formed around its outer periphery.

When the optical fiber thus obtained was compared with an optical fiber without the glass layer 3 (conventional example), the optical fiber according to the present invention was superior to the conventional example in both weather resistance and mechanical properties.

Furthermore, by increasing the outer diameter of the entire base material in the rod-in-tube method, it was possible to increase the processing rate and easily reduce the core diameter.

(Effects of the Invention) As explained above, since the germanium oxide optical fiber according to the present invention has a weather-resistant glass layer of silica glass on the outer periphery of the cladding, the germanium oxide core and the cladding are connected to each other through the glass layer. The optical fiber can be protected from moisture in the air, thus increasing the durability of the optical fiber, and since the weather-resistant glass layer is made of silica glass, which is cheaper than germanium oxide, there is no significant cost increase, and the connection is easy. It is also possible to satisfy the requirements for an outer diameter dimension that makes handling easier and for other purposes, as well as a smaller core diameter.

[Brief explanation of the drawing]

The drawing is a sectional view showing one embodiment of an optical fiber according to the present invention. l...Core 2...Fist cladding 3...Weather-resistant glass layer

Claims (3)

[Claims] (1) An optical fiber whose core and cladding are germanium oxide based, in which a weather-resistant glass layer of silica glass having a refractive index equal to or higher than that of the cladding is formed around the outer periphery of the cladding. optical fiber. (2) The germanium oxide optical fiber according to claim 1, wherein the weather-resistant glass layer contains 0 to 90% SiO_2. (3) The germanium oxide optical fiber according to claim 1 or 2, wherein the weather-resistant glass layer has a refractive index of 1.58 or more.