JPS5939740A - Manufacture of optical fiber - Google Patents

Abstract

PURPOSE:To obtain an optical fiber having long-term mechanical reliability, by implanting ions into the surface of a preform for an optical fiber consisting of a core part and a clad part and by drawing the preform. CONSTITUTION:Ions are implanted into the surface of a preform for an optical fiber consisting of a core 1 and a clad 2 with an ion implanting device to form a surface film 3. The perform is optionally annealed, and it is drawn to obtain an optical fiber having a uniform thin film. The preferred ions to be implanted are ions of C, N, Al, Ti, In or Sn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an optical fiber having long-term mechanical reliability.

In optical fibers made of glass, moisture enters into minute surface defects that occur during manufacturing and subsequent handling, and the defects grow under stress, causing static fatigue, which can lead to the original fiber breaking. However, this poses a problem in terms of guaranteeing the long-term reliability of optical fiber.

As a countermeasure, methods such as coating the drawn optical fiber with a film of an inorganic compound such as Si3N4, 5N02, or TiN by CVD, or melt-coating a metal such as Aj or N are used. It is being However, although such a method has the effect of improving weather resistance, it is difficult to apply a uniform coating of several μm to an optical fiber of about 100 to 200 μm.
It is difficult to form a thin film with a thickness of less than m, and conversely, defects occur on the surface of the optical fiber during the process of coating the thin film, resulting in a decrease in initial strength.

The present invention provides a method for manufacturing an optical fiber having a uniform weather-resistant coating without the above-mentioned drawbacks. An optical fiber having a uniform thin film is manufactured by implanting ions using an ion implanter to form a surface film layer 3, performing annealing if necessary, and then drawing. The line is 2000-23
At 00°C, the preform to fiber outer diameter ratio is 100.
Do this until it becomes about 400.

Conventional inorganic coating during drawing is done while winding the fiber, making it difficult to coat it uniformly, but in the present invention, ions are implanted onto the surface of a thick, stationary preform, making it easier to control the film thickness. It is easy to form a uniform film.

The ion species to be implanted are O, N, Al, Ti, and V.

Cr, Mn, Fe, Co, Ni,
C! u, Zn, Ag, Cd, In.

Sn, Sb, etc., among others, O, N, Al
, Ti, In.

Sn is preferred. This means that C is SiO, N is Si, and N
υ, At, Ti may form a weather-resistant film of 4.
A, g203, 'rio2 oxide film is formed on the surface, and there is a possibility that the weather resistance will be improved.
This is because similar expectations can be expected. ion implantation depth,
The amount of ions injected depends on the outer diameter of the preform and the ion species, but the implantation depth is usually in the range of 0.1 μm to 10 μm, and the optimum injection amount is in the range of 1016 ions/Cm2 to 101'' ions/Cm2. In addition, ion implantation often causes lattice defects, which may reduce the strength of the optical fiber, but as a countermeasure,
It is preferable to perform annealing at a temperature in the range of 00°C to 2500°C over a time period of 10 minutes to 10 o'clock.

The method for renovating the "optical fiber puff" is an OV method in which raw material gases such as 5iO14 and Ge014 are passed through a quartz pipe, the outside is heated with a burner, and glass is laminated.
Method D, 5iC4 from oxyhydrogen burner.

VAD that deposits glass by flowing raw material gas such as Ge04
There are laws etc. Core VC is Ge102 doped 5i
02, 5i02 is used as the cladding material, the pref calm diameter is between 10 and 40φ, and the core/cladding ratio is 0.1.
・-〇, 8 is common 1゜Example 5 x 1017 N ions/
Ca11”, implanted at a depth of 1 pm and heated at 1500°C for 3
After time annealing, it was drawn into an optical fiber with a core of 50 μm and a cladding of 125 μm. The static fatigue parameter of this optical fiber was n=42, which was twice the n value of n-20 for the optical fiber without ion implantation. The initial strength was comparable in both cases.

[Brief explanation of the drawing]

The attached figure is a sectional view showing the structure of an optical fiber preform according to the present invention. Agents 1) Akira’s agent Ryo Hagiwara −

Claims (1)

[Claims] A method for manufacturing an optical fiber, which comprises injecting accelerated ions into the surface of an optical fiber preform formed by a core portion and a cladding portion using an ion implantation method, and then drawing the preform.