JPH01167812A - Optical fiber cable - Google Patents

Abstract

PURPOSE:To obtain exit light of <=300nm wavelength at the front end of a cable and to constitute an apparatus having high safety by providing a nonlinear optical element to the laser light exit end of an optical fiber. CONSTITUTION:The nonlinear optical element 3 formed by using beta-BaB2O4 and a condenser lens 3 are provided to the front end of the optical fiber 1 in a protective tube 2. A crystal which is cut out by determining the orientation according to the wavelength of incident light is used for the nonlinear optical element 3 in such a manner that second harmonic wave can be phase-matched at room temp. The laser light of 514.5nm wavelength emitted from an oscillator is converted by the optical element 3 to 257.3nm wavelength and is condensed by the lens 5. The condensed light is projected to an object. The exit light of <=300nm wavelength is, therefore, obtd. at the front end of the tube and the apparatus having high safety is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical fiber cable used for medical purposes, biological and chemical industrial processes, and the like.

BACKGROUND OF THE INVENTION Conventional optical fiber cables are described, for example, in Endoscope 5 (1973), p. 208.
V, 5 (1973) p208). FIG. 3 shows a cross-sectional side view of the light emitting end of this conventional optical fiber cable, where l is an optical fiber made of quartz glass for guiding the laser light emitted from the laser oscillator. 2 is a protective tube surrounding the optical fiber 1, and 5 is a lens or window for condensing the laser beam emitted from the optical fiber 1. 6
is a tube that surrounds the protective tube 2 and has the lens or window 5 located at its end.

In the conventional optical fiber cable configured as described above, the laser light generated by the laser oscillator propagates through the optical fiber 1, passes through the lens or window 5, and is emitted toward the target object.

Problems to be Solved by the Invention However, with the above configuration, when a laser beam emitted from a laser light source having a wavelength of 300 nm or less, such as an excimer laser, is propagated to a target site, the propagation loss of the optical fiber is high. It was so large that it was difficult to put it into practical use. Furthermore, laser light in this wavelength band causes damage to the human body, and transmission through optical fibers has the problem of being highly dangerous in terms of equipment configuration and handling.

In view of these points, the present invention provides an optical fiber cable that can propagate laser light having a wavelength in the visible range that is safer for the human body through the optical fiber, and can irradiate a target object with laser light with a wavelength of 300 nm or less. The purpose is to

Means for Solving the Problems The present invention is an optical fiber cable that includes a nonlinear optical element at the laser beam emitting end of the optical fiber.

According to the above-described configuration, the wavelength of the laser light emitted from the laser oscillator and propagated through the optical fiber is converted by the nonlinear optical element after being emitted from the optical fiber. When guided to an object, the target object is irradiated with a laser beam having a wavelength of 300 nm or less.

A nonlinear optical element is one that generates optical harmonics with frequencies of 2ω, 3ω, etc. when light with a fundamental frequency ω is incident thereon due to the high-order polarization with respect to the electric field exhibited by a specific crystal. , is an element that can easily convert the wavelength of laser light to 1/2 or 1/3, etc.

Embodiment FIG. 1 shows a cross-sectional side view of a light emitting end of an optical fiber cable in an embodiment of the present invention. In FIG. 1, 1 is an optical fiber made of quartz glass for guiding laser light emitted from a laser oscillator, 2 is a protective tube surrounding the optical fiber l, and 3 is a β-Ba
A nonlinear optical element using B20a, 4 a mount for fixing the nonlinear optical element 3 and connecting it to the optical fiber l, 5 a lens for condensing the output light wavelength-converted by the nonlinear optical element 3, 6 is a tube having the mount 4 as its tip. The nonlinear optical element 3 uses a crystal cut out and oriented in accordance with the wavelength of the incident light so that the second harmonic can be phase-matched at room temperature.

The operation of the optical fiber cable of this embodiment configured as described above will be described below. FIG. 2 shows an example of operation when an argon laser oscillator is used as a light source. A laser beam 8 with a wavelength of 514.5 nm emitted from the oscillator is guided to the tip of the optical fiber 1, condensed by a lens 7 formed on the output end face of the optical fiber 1, and incident on the nonlinear optical element 3. The laser beam 9 whose wavelength has been converted to 257.3 nm by the nonlinear optical element 3 is focused by a lens 5 fixed to a mount 4, and is irradiated onto a target object. At this time, in order to prevent simultaneous irradiation of the incident laser beams 8 with a wavelength of 514.5 nm, a lens 5 having wavelength selectivity may be used, or a filter may be provided separately. 10 is a connector for connecting this optical fiber cable to a laser oscillator.

As described above, according to this embodiment, the optical absorption edge wavelength is 200
By attaching a nonlinear optical element using β-BaB204, which exists in the nm wavelength or less, to the tip of an optical fiber, visible argon laser light is propagated through the optical fiber, and ultraviolet light with a wavelength of 257.3 nm is transmitted at the tip of the optical fiber cable. Obtainable.

In this example, the nonlinear optical element 3 is a crystal cut to a desired size and used as it is. A thin film optical waveguide structure may be used for purposes such as increasing the optical density. Also,
The lens 5 may be a window that does not have a light condensing property, or the window may be configured to have wavelength selectivity. Further, as the nonlinear element, it is also possible to use urea (Ur, ea), crystal, or the like.

As described in detail, according to the present invention, visible laser light is propagated through an optical fiber by the wavelength conversion effect of a nonlinear optical element, and an output light having a wavelength of 300 nm or less is obtained at the tip of the cable, and a target object is can be irradiated. Therefore, it is possible to use a conventional silica glass fiber as an optical fiber, and it is possible to construct a device that is highly safe for the human body, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of a laser beam emitting end of an optical fiber cable according to an embodiment of the present invention, FIG. 2 is a cross-sectional side view of the same embodiment, and FIG. 3 is a cross-sectional side view of a conventional optical fiber cable. It is. l...Optical fiber, 2...Protection tube, 3...
Nonlinear optical element, 4...Mount, 5...Lens or window, Agent's name Patent attorney Toshio Nakao 1 idiot/---Optical phino 2-Insolent Teugue 3-NoP linear optical element 4 - Mount 7 - Kukai section 8 - 674.6rtm Liquid 4V - Light 2nd e
l9---2,57.3nm
1R4e radar optical lθ-connector

Claims (2)

[Claims] (1) An optical fiber that propagates laser light, a nonlinear optical element that converts the wavelength of the laser light emitted from the end of the optical fiber, and a nonlinear optical element that accommodates the optical fiber and the nonlinear optical element inside and near the end. An optical fiber cable comprising: a tube having a lens or a window; and a tube having a lens or a window. (2) The optical fiber cable according to claim 1, characterized in that β-BaB_2O_4 is used as the nonlinear optical element.