Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-07-26
2003-03-18
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S180000, C264S001240, C264S001280, C264S001290, C372S006000
Reexamination Certificate
active
06533883
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of manufacturing an optical medium, and in particular, to a manufacturing method suitable for an optical fiber oscillator or an optical waveguide laser oscillator.
In a field of an optical communication or a laser process, it has been desirably required to develop a cheaper laser device having a higher output.
Conventionally, an optical fiber laser device has been known as a device satisfying this requirement.
In such an optical fiber device, a core diameter and index of refraction between a core and a clad are suitably selected. Thereby, a laser light beam of high quality can be relatively simply obtained.
Further, an interactive operation between laser active substance and the light beam can be enhanced by sealing the light beam with high density.
Moreover, an interactive operation length can be enlarged by lengthening the optical fiber. Thereby, the laser beam having the high quality can be spacially generated with high efficiency. Consequently, the laser light beam of high quality can be relatively cheaply obtained.
In this case, it is necessary to efficiently introduce an excitation light beam into a doping region (generally, referred to as a core portion) of a luminescent center (hereinafter, referred to as laser active substance), such as, a laser active ion, a color element of the optical fiber in order to realize further high-output and high-efficiency of the laser light beam.
Meanwhile, when the core diameter is generally set so as to satisfy a waveguide condition of a single mode, the diameter is restricted to several tens &mgr;m or less. In consequence, it is generally difficult to efficiently introduce the excitation light beam for the small core diameter.
To solve such a problem, suggestion has been made about a double clads type fiber laser, for example, as disclosed in H. Zellmer, U. Willamowski, A. Tunnermann, and H. Welling, Optics Letters. Vol. 20, No.6, pp. 578-580, March, 1995.
In such a double clads type fiber laser, a first clad portion having lower index of refraction than the core portion is arranged around the core portion, and a second clad portion having further lower index of refraction is provided at an outside portion thereof.
Thereby, the excitation light beam introduced into the first clad portion propagates by total reflection due to a difference of index of refraction between the first clad portion and the second clad portion on the condition that the excitation light beam is sealed in the first clad portion.
During the propagation, the excitation light beam repeatedly passes the core portion to excite the laser active substance of the core portion.
In this event, the first clad portion has a large area of about hundred times in comparison with the core portion. Consequently, it is possible to further introduce many excitation light beams and to produce a high output.
In the double clads type fiber laser advantageously has high oscillation efficiency and a single and stable oscillation lateral mode.
Further, an output within the range between several watt to about 10 watt can be obtained by the use of a laser diode (hereinafter, abbreviated as a LD). In consequence, a further higher output can be realized as compared to the conventional core type fiber laser.
However, edge excitation is carried out from an edge or both edges of the fiber in such a double clads type fiber laser. Consequently, the number of the LDs for excitation can not be increased.
Namely, it is indispensable to achieve a high output of an introduced LD to produce a laser light beam having an high output in the double clads type fiber laser.
To solve this problem, suggestion has been made about a method for bundling a plurality of double clads type fiber lasers to achieve the high output. Although an average output can be increased with the bundled number, brightness is inevitably lowered. This reason will be explained below.
Namely, the core portions as luminescent points are widely dotted in a space because a larger clad portion (having a diameter of about 100 times) than the core is attached to the core portion. Thus, light-gathering performance can not be enhanced only by bundling a plurality of fiber lasers.
Therefore, another suggestion has been made about a laser device in which a fiber is repeatedly folded or wound in a disk-like region or a cylindrical region, and a plurality of LD light sources (beams) are inputted as excitation light beams from the periphery of the fiber laser having the disk-like structure or the cylindrical structure, as disclosed in Japanese Unexamined Patent Publication No. Hei. 10-135548, or Hei. 10-190097.
However, when these laser devices are manufactured, the fiber is dipped in resin and cured or hardened to keep these shapes after the fiber is formed to the disk-shape or the cylindrical shape.
In consequence, it is difficult to manufacture the fiber and to form to an arbitrary shape.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a method of manufacturing an optical medium which is readily capable of manufacturing it.
It is another object of this invention to provide a method of manufacturing an optical medium which is capable of improving a laser output by using a fiber laser which is superior in light-gathering performance and has a thermally stable output and a lateral mode.
According to a first aspect of this invention, an optical medium is manufactured by the following steps.
An extended optical conductor containing active substance is first formed to a predetermined shape by the use of resin by repeatedly folding or winding the optical conductor.
A laser light beam or an amplified light beam is outputted from an edge portion of the optical conductor by absorbing an excitation light beam incident from a side surface of the optical conductor into the active substance through the resin.
Thermoplastic resin is used as the resin. In this event, the thermoplastic resin transmits the excitation light beam.
The resin is heated up to a glass transition temperature or higher.
The optical conductor and the resin are bonded to each other so as to constitute a predetermined shape. Finally, the resin is cured.
In the first aspect, the fiber is repeatedly folded or wound in a region of a disk shape or a cylindrical shape. The excitation light beams can be incident through a plurality of LD light sources from the periphery of the fiber laser having the disk shape or the cylindrical shape. Thereby, the laser output can be increased.
The fibers must be bonded or welded and be integrated the desired shape in order to mold the fiber for the fiber laser to the disk shape or the cylindrical shape.
As the molding method, it may be readily assumed that the fiber containing glass as a main component is thermally welded.
However, when the fiber is formed by only the glass material in this method, thermal deformation temperature becomes high (several hundreds ° C. or higher). Consequently, the molding process is not easy.
Further, the fiber is often damaged in the molding process by an affect of scratches which may be made in the molding process. Therefore, the resin is generally coated so as to enhance the strength of the fiber.
The first aspect is characterized in that the thermoplastic optical resin is used as the resin material for coating the fiber. In this case, the thermoplastic optical resin can be readily and thermally molded.
Moreover, the thermoplastic optical resin can be coated onto the fiber surface by the in-line process in the step for making the fiber from the fiber preform as serving as the starting material. In consequence, the desired laser fiber can be readily produced.
In addition, thermal deformation generally occurs at a low temperature of about 200° C. or lower in the thermoplastic resin. Consequently, the fiber laser having the disk shape or the cylindrical shape can be readily and thermally molded.
In this case, phenol resin or melamine resin is the thermosetting resin having a bridge point. When the heating temperature is gradually incr
Itoh Katsuhisa
Tanaka Akiyoshi
Ball Michael W.
Haran John T.
Hoya Corporation
LandOfFree
Method of manufacturing optical medium does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing optical medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing optical medium will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3064908