JP2007034221A - Optical fiber device, manufacturing method thereof, and mode-synchronous optical fiber laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber device capable of reducing return light, a manufacturing method of the optical fiber device, and a mode-synchronous optical fiber laser device. <P>SOLUTION: The optical fiber device 16 of the mode-synchronous optical fiber laser device 1 includes an optical fiber 161, a reflection protective film 16B arranged on an end face of this optical fiber 161, a layer 16C containing carbon nano-tubes, and an SiO<SB>2</SB>film 16D as a protective film. The end face of the optical fiber 161 is an inclined plane against the optical axis of the optical fiber, and the layer 16C containing the carbon nano-tubes is arranged almost parallel to the inclined plane. An angle of inclination of the inclined plane is 6°or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical fiber device, a method for manufacturing the optical fiber device, and a mode-locked optical fiber laser device.

In recent years, in the field of optical communication, attempts have been made to reduce noise from various optical devices such as optical amplifiers, that is, amplified spontaneous emission (ASE), and improve the SN ratio. For example, a method has been proposed in which carbon nanotubes (CNT), which are saturable absorbers, are used to prevent noise transmission and improve the SN ratio (see, for example, Patent Document 1).
Specifically, in Patent Document 1, a carbon nanotube-containing layer (CNT layer) is formed on the end face of the optical fiber and the end face of the ferrule, and an ultraviolet curable resin is applied on the layer containing the carbon nanotube. The structure to perform is disclosed.

JP 2004-280028 A (Page 7, FIG. 5)

However, the technique of Patent Document 1 has room for improvement in the following points.
The light from the optical fiber is reflected at the interface between the end face of the optical fiber and the carbon nanotube-containing layer (CNT layer) and at the outer surface of the CNT layer (the surface opposite to the end face of the optical fiber). The
Since the interface between the end face of the optical fiber and the CNT layer and the outer surface of the CNT layer are vertical surfaces, the reflected light at the interface between the end face of the optical fiber and the CNT layer, the reflected light at the outer surface of the CNT layer However, it returns to the inside of the core of the optical fiber, and return light is generated.
In addition, since the CNT layer is provided on the end face of the optical fiber, the return light from the interface between the end face of the optical fiber and the CNT layer and the return light from the outer surface of the CNT layer are generated. There is also a risk of interference inside the optical fiber.
Therefore, when the configuration disclosed in Patent Document 1 is applied to a mode-locked optical fiber laser device, there is a possibility that mode-locking of the optical fiber laser device is broken due to the influence of return light.

  An object of the present invention is to provide an optical fiber device, a method of manufacturing an optical fiber device, and a mode-locked optical fiber laser device that can reduce return light.

  An optical fiber device of the present invention includes an optical fiber and a layer containing carbon nanotubes provided on the end face of the optical fiber, and the end face of the optical fiber is inclined with respect to the optical axis of the optical fiber. The layer containing an inclined surface and containing the carbon nanotubes is provided substantially parallel to the inclined surface.

Here, a layer containing carbon nanotubes may be provided directly on the end face of the optical fiber, and the layer containing carbon nanotubes is indirectly provided on the end face of the optical fiber via another layer or film. May be provided.
Also, the type of optical fiber is not particularly limited, and may be, for example, a rare earth-doped optical fiber to which rare earth is added as an optical amplification medium.
Since the end surface of the optical fiber is an inclined surface, the reflected light reflected by the end surface of the optical fiber travels obliquely with respect to the optical axis of the optical fiber. For this reason, the reflected light passes out of the core of the optical fiber. Thereby, generation | occurrence | production of return light can be prevented.
In addition, since the layer containing the carbon nanotubes is substantially parallel to the end face of the optical fiber, which is an inclined surface, the surface of the layer containing the carbon nanotubes also becomes an inclined surface. Accordingly, the reflected light reflected from the surface of the layer containing the carbon nanotubes also escapes outside the core of the optical fiber, thereby preventing the generation of return light.
Furthermore, in the present invention, the reflected light at the end face of the optical fiber and the reflected light at the surface of the layer containing the carbon nanotubes escape to the outside of the core of the optical fiber. There is no interference.
Here, that the layer containing the carbon nanotubes is substantially parallel to the inclined surface of the optical fiber means that an error in the range where the effects of the present invention are exerted is allowed.

Furthermore, in the present invention, it is preferable that an angle formed between the inclined surface and a surface orthogonal to the optical axis of the optical fiber is 6 ° or more. Especially, it is preferable that the said angle is 8 degrees or more. The angle is preferably 20 ° or less, and more preferably the angle is 12 ° or less.
Thus, by making the angle formed by the inclined surface and the surface perpendicular to the optical axis of the optical fiber 6 ° or more, the generation of return light can be reliably prevented.

In the present invention, an antireflection film is preferably provided on the end face of the optical fiber.
By forming the antireflection film, generation of reflected light can be reduced.

Furthermore, in this invention, it is preferable that the protective film which covers the layer containing this carbon nanotube is provided on the layer containing the said carbon nanotube.
By forming a protective film on the layer containing carbon nanotubes, the layer containing carbon nanotubes can be protected and the carbon nanotubes can be prevented from falling off.
Here, examples of the protective film include a SiO ₂ film, a Si film, a TaO ₅ film, a MgO film, and a MgF ₂ film. It is preferable that the protective film is hardly deteriorated by light transmission and has high heat resistance and durability. Furthermore, as the protective film, those having excellent adhesion to the layer containing carbon nanotubes are preferable.

Furthermore, in the present invention, there is a ferrule through which an end of the optical fiber is inserted, the end surface of the ferrule and the end surface of the optical fiber are substantially on the same plane, and the end surface of the ferrule and the end surface of the optical fiber Is provided with an antireflection film containing an inorganic substance, and a layer containing the carbon nanotube is provided on the antireflection film, and the protection containing an inorganic substance is provided on the layer containing the carbon nanotube. It is preferable that a film is provided, the outer periphery of the antireflection film is not covered with the layer containing the carbon nanotubes, and the protective film is in contact with the outer periphery of the antireflection film.
The outer peripheral portion of the antireflection film is not covered with a layer containing carbon nanotubes, and the protective film is in contact with the outer peripheral portion of the antireflection film. Since the antireflection film is a layer containing an inorganic substance, it has good adhesion to a protective film containing an inorganic substance. Therefore, peeling of the protective film can be prevented, and the layer containing carbon nanotubes can be reliably protected.
Here, in the case of forming an antireflection film, a layer containing carbon nanotubes, and a protective film on the end face of the ferrule and the end face of the optical fiber, the antireflective film is made of the refractive index of the core of the optical fiber and the carbon nanotube. The antireflection film may be an antireflection film in consideration of the refractive index of the containing layer, and the protective film may be an antireflection film in consideration of the refractive index of air and the refractive index of the layer containing carbon nanotubes.
By setting it as such a structure, generation | occurrence | production of reflected light can be suppressed reliably.

Furthermore, in the present invention, the layer containing carbon nanotubes preferably contains the carbon nanotubes and a binder material.
When the layer containing carbon nanotubes contains the binder material, it is possible to prevent the carbon nanotubes from falling off.
Here, the binder material may be any material that binds the carbon nanotubes, and may be any material that transmits light propagating through the optical fiber.
For example, examples of the binder material include those made of ultraviolet curable resin, polyimide resin, PVA, and the like.

The carbon nanotube is preferably an open-ended carbon nanotube whose end is decorated with at least one of a carboxyl group and a hydroxyl group.
Thus, the use of open-end carbon nanotubes whose ends are decorated with carboxyl groups and hydroxyl groups makes it easier to disperse the carbon nanotubes in the solvent. Therefore, a layer containing carbon nanotubes in which carbon nanotubes are uniformly dispersed can be formed.

Furthermore, the optical fiber is preferably composed of a polarization maintaining optical fiber.
According to the present invention, by configuring the optical fiber with a polarization maintaining optical fiber, it is possible to reliably maintain the polarization state of the light propagated through the optical fiber.

In the present invention, a filter on which light amplified by an optical amplifying medium excited by light from a laser light source is incident is provided on the end face of the optical fiber, and the filter emits from the laser light source. It is preferable that the light that is reflected is transmitted and the amplified light is transmitted, and a layer containing the carbon nanotube is provided on the light emission side of the filter.
Most of the light from the laser light source is absorbed by the optical amplification medium, but some light from the laser light source may not be absorbed by the optical amplification medium. Since light from a laser light source is generally strong, if such light is incident on a layer containing carbon nanotubes, the layer containing carbon nanotubes may be deteriorated.
Further, when strong light from a laser light source is incident on a layer containing carbon nanotubes, the saturable characteristic of the layer containing carbon nanotubes may be saturated. For this reason, noise may pass through the layer containing the carbon nanotubes.
In the present invention, a filter that reflects the light emitted from the laser light source and transmits the light amplified by the optical amplifying medium is provided on the end face of the optical fiber of the optical fiber device. It is possible to prevent light from a laser light source from entering the layer. Thereby, deterioration of the layer containing a carbon nanotube can be prevented. Furthermore, saturation of the saturable property of the layer containing carbon nanotubes can be prevented.
The filter may be directly formed on the end face of the optical fiber, or may be indirectly formed through another film or layer formed on the end face of the optical fiber.
Furthermore, the layer containing carbon nanotubes may be directly formed on the filter, or may be indirectly formed through another layer or a film.

The mode-locked optical fiber laser device according to the present invention includes a laser light source and an optical amplification region to which light from the laser light source is supplied, and a part of the light emitted from the optical amplification region is again transmitted to the light A mode-locked optical fiber laser device that is introduced into the amplification region and outputs another part of the light emitted from the optical amplification region, comprising any of the optical fiber devices described above.
According to the present invention, since any one of the optical fiber devices described above is provided, the return light can be reduced, and the mode synchronization of the optical fiber laser device can be reliably prevented from being lost. Can do.
When the optical fiber of the optical fiber device is a rare earth-doped optical fiber to which rare earth is added, the optical amplification region is formed in the optical fiber of the optical fiber device.
Here, when the layer containing the carbon nanotube is provided only on one end face of the optical fiber of the optical fiber device, the end face provided with the layer containing the carbon nanotube is more than the other end face of the optical fiber. However, it is preferable to arrange the optical fiber device so as to be at the front end side in the light output direction of the mode-locked optical fiber laser device or the front end side in the light propagation direction.

  The method of manufacturing an optical fiber device according to the present invention is a method of manufacturing an optical fiber device including an optical fiber, wherein the end surface of the optical fiber is an inclined surface inclined with respect to the optical axis of the optical fiber; Providing a layer containing carbon nanotubes on the end face of the optical fiber, and the step of providing a layer containing carbon nanotubes is obtained by dispersing the carbon nanotubes in a solvent, centrifuging, and then extracting the supernatant, It includes a step of coating on the end face of the optical fiber.

Here, in the present invention, in the step of providing the layer containing carbon nanotubes, the solvent in which the carbon nanotubes are dispersed is centrifuged, and then the supernatant is extracted, and this supernatant is centrifuged again to further extract the supernatant. It is preferable to apply the supernatant to the end face of the optical fiber after repeating the above operation a plurality of times.
According to the present invention, after centrifuging the solvent in which the carbon nanotubes are dispersed, the supernatant is extracted, and this supernatant is applied to at least the end face of the optical fiber. A layer containing nanotubes can be formed.

  ADVANTAGE OF THE INVENTION According to this invention, the optical fiber apparatus which can reduce return light, the manufacturing method of an optical fiber apparatus, and a mode synchronous optical fiber laser apparatus are provided.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.
In this embodiment, the end surface of the optical fiber is an inclined surface inclined with respect to the optical axis of the optical fiber, and a layer containing carbon nanotubes substantially parallel to the inclined surface is provided on the end surface of the optical fiber. The present invention relates to an optical fiber device.
FIG. 1 shows a mode-locked optical fiber laser device 1 having such an optical fiber device.
Specifically, the mode-locked optical fiber laser device 1 includes a pumping laser light source 11, a WDM (optical wavelength division multiplexed) module 12, an optical amplifier 13 to which pumping light from the pumping laser light source 11 is supplied, The half mirror module 14, a plurality of optical fiber devices 15 connecting them, and an optical fiber device 16 are provided.

The WDM module 12, the optical amplifier 13, and the half mirror module 14 are connected in a ring shape by optical fiber devices 15 and 16.
The WDM module 12 includes an isolator 121 that allows light to flow in one direction, and a WDM filter 122 that is disposed closer to the front side in the light propagation direction than the isolator 121. The isolator 121 and the WDM filter 122 are disposed in the housing 123.
The WDM filter 122 reflects light near the 980 nm wavelength and transmits light near the 1550 nm wavelength. That is, the light from the excitation laser light source 11 is reflected and the light introduced from the half mirror module 14 through the optical fiber device 16 is transmitted.
An antireflection film (not shown) is formed on the WDM filter 122.

  The excitation laser light source 11 is arranged so as to irradiate laser light toward the WDM filter 122 of the WDM module 12. The excitation laser light source 11 is a laser diode, and in the present embodiment, laser light having a wavelength of 975 nm is output at an output power of 60 mW.

An optical fiber device 15 is disposed between the excitation laser light source 11 and the WDM module 12, and guides light from the excitation laser light source 11 to the WDM module 12.
The optical fiber device 15 includes an optical fiber 152, a ferrule 151 attached to one end of the optical fiber 152, and a collimator lens L.
The collimator lens L changes the light from the optical fiber 152 into parallel light, and is an aspheric lens. The collimator lens L and the ferrule 151 are accommodated in the housing 153, and the relative positions are fixed.
The optical fiber 152 is a single mode polarization maintaining optical fiber.
The ferrule 151 is one into which one end of the optical fiber 152 is inserted. The ferrule 151 includes a main body portion 151A and a protruding portion 151B that is inserted into the tip of the main body portion 151A and protrudes from the main body portion 151A. The main body 151A is made of metal, for example, SUS. The main body portion 151A includes a large-diameter portion 151A1 and a small-diameter portion 151A2 that is integrally formed with the large-diameter portion 151A1 and has a smaller diameter than the large-diameter portion 151A1.
The protruding portion 151B is inserted into the large diameter portion 151A1 of the main body portion 151A and has a smaller diameter than the large diameter portion 151A1. This protrusion 151B is made of ceramic.
One end face of the projecting portion 151B (the end face located on the side opposite to the large diameter portion 151A1) and the end face of the optical fiber 152 inserted into the ferrule 151 are on the same plane, and are relative to the optical axis of the optical fiber 152. The slope is inclined.
Further, an antireflection film (not shown) is formed on the end face of the optical fiber 152 and one end face of the protruding portion 151 </ b> B of the ferrule 151.

An optical fiber device 15 is also connected to the front end side of the WDM module 12 in the light propagation direction.
The optical fiber device 15 is an optical fiber device having the same configuration as the optical fiber device 15 disposed between the excitation laser light source 11 and the WDM module 12, and includes an optical fiber 152 and one end of the optical fiber 152. And a collimator lens L, and a housing 153.
The other end of the optical fiber 152 of the optical fiber device 15 is connected to the optical amplifier 13.

The optical amplifier 13 is arranged on the front side in the light propagation direction with respect to the WDM module 12 and the excitation laser light source 11.
The optical amplifier 13 has a rare earth doped optical fiber. This rare earth-doped optical fiber is an optical fiber in which a rare-earth (light amplification medium) such as ytterbium (Yb) or erbium (Er) is added to the core portion of a single mode optical fiber. The optical amplification medium is excited by light from the excitation laser light source 11 and amplifies the light.
In this embodiment, for example, an erbium (Er) -doped optical fiber having a large gain in the vicinity of a wavelength of 1550 nm is used.
This rare earth-doped optical fiber becomes an optical amplification region.

  Further, an optical fiber device 15 is disposed on the front side of the optical amplifier 13 in the light propagation direction. The optical amplifier 13 is connected to a half mirror module (branching means) 14 through an optical fiber device 15.

The half mirror module 14 includes an isolator 141 and a half mirror 142 disposed on the front side in the light propagation direction from the isolator 141. The isolator 141 and the half mirror 142 are arranged in the housing 143.
The half mirror 142 reflects a part of the light transmitted from the isolator 141 and transmits the other part of the light transmitted from the isolator 141. Here, in this embodiment, the ratio of the reflected light reflected by the half mirror 142 and the transmitted light transmitted through the half mirror 142 is 1: 1. The reflected light is taken out of the housing 143 and output as laser light from the optical fiber 152 via the collimator lens L and the ferrule 151 of the optical fiber device 15.
On the other hand, the light transmitted through the half mirror 142 enters the optical fiber device 16 connected to the half mirror module 14 and is guided to the WDM module 12 by the optical fiber device 16.
Note that an antireflection film (not shown) is formed on the half mirror 142.

The half mirror module 14 and the WDM module 12 are connected via an optical fiber device 16.
The optical fiber device 16 includes an optical fiber 161 for propagating light, a pair of ferrules 151 and 163 connected to a pair of ends of the optical fiber 161, and a pair of collimator lenses L, respectively.
Of the pair of collimator lenses L, the collimator lens L on the half mirror module 14 side is for condensing the light transmitted through the half mirror 142 onto the optical fiber 161. The collimator lens L on the half mirror module 14 side is disposed in the housing 153 together with the ferrule 151.
Of the pair of collimator lenses L, the collimator lens L on the WDM module 12 side is for making the light from the optical fiber 161 parallel light and introducing the parallel light into the WDM module 12. The collimator lens L on the WDM module 12 side is disposed in the housing 164 together with the ferrule 163.

The optical fiber 161 is a single-mode polarization maintaining optical fiber.
The pair of ends of the optical fiber 161 are inserted into ferrules 151 and 163, respectively.
The ferrule 163 has the same structure as the ferrule 151, and includes a main body portion 163A and a protruding portion 163B that is inserted into the distal end of the main body portion 163A and protrudes from the main body portion 163A. The main body portion 163A includes a large-diameter portion 163A1, and a small-diameter portion 163A2 that is integrally formed with the large-diameter portion 163A1 and has a smaller diameter than the large-diameter portion 163A1.
As shown in FIG. 2, the protruding portion 163B is inserted into the large-diameter portion 163A1 of the main body portion 163A and has a smaller diameter than the large-diameter portion 163A1. This protrusion 163B is made of ceramic.
As shown in FIG. 2, one end face of the protrusion 163 </ b> B (the end face located on the side opposite to the large diameter part 163 </ b> A <b> 1) and the end face of the optical fiber 161 inserted into the ferrule 163 are on the same plane. The end surface 163B1 of the protruding portion 163B and the end surface 161A of the optical fiber 161 are inclined surfaces that are inclined with respect to the optical axis X of the optical fiber 161 (the longitudinal direction of the optical fiber 161).
The inclination angle θ of the inclined surface is 6 ° or more and 12 ° or less, and preferably 8 ° or more and 12 ° or less. Here, the inclination angle θ is an angle formed by a plane perpendicular to the optical axis X of the optical fiber 161 and the inclined plane.

Further, on the end face 163B1 of the protrusion 163B of the ferrule 163 and the end face 161A of the optical fiber 161, as shown in FIG. 2, an antireflection film 16B, a layer 16C containing carbon nanotubes, and an SiO ₂ film (protective film) ) 16D is laminated.
The antireflection film 16B is formed substantially in parallel with the end surface 163B1 of the protrusion 163B of the ferrule 163B and the end surface 161A of the optical fiber 161 along the end surface 163B1 of the protrusion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161. . This antireflection film 16B is made of an inorganic material, and has a structure in which, for example, a SiO ₂ film and a Ta ₂ O ₅ film are laminated. The antireflection film 16B is formed so as to cover the entire end surface 163B1 of the protrusion 163B of the ferrule 163 and the entire end surface 161A of the optical fiber 161.

Further, a layer 16C containing carbon nanotubes is formed on the antireflection film 16B.
The carbon nanotube-containing layer 16C is formed along the inclination of the end face 163B1 of the protrusion 163B of the ferrule 163 and the end face 161A of the optical fiber 161, and the layer 16C containing the carbon nanotube is the protrusion 163B of the ferrule 163. The end face 163B1 and the end face 161A of the optical fiber 161 are substantially parallel to each other.
As shown in FIG. 3, the planar shape of the carbon nanotube-containing layer 16C is composed of the planar shape of the antireflection film 16B (that is, the end surface 163B1 of the protruding portion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161). The carbon nanotube-containing layer 16C is not formed on the outer peripheral portion of the antireflection film 16B. Accordingly, the outer peripheral portion of the antireflection film 16B is exposed. In FIG. 3, a SiO ₂ film 16D described later is not shown.
The layer 16C containing carbon nanotubes only needs to be formed so as to cover at least the core of the optical fiber 161 in the end surface 161A of the optical fiber 161.

Here, the carbon nanotubes contained in the layer 16C containing carbon nanotubes have saturable absorption characteristics at 1200 nm to 2000 nm as shown in FIG.
The carbon nanotubes contained in the carbon nanotube-containing layer 16C may be any carbon nanotubes that exhibit saturable absorption characteristics in a wavelength region including the wavelength of light emitted from the mode-locked optical fiber laser device 1. FIG. It is not restricted to what has a saturable absorption characteristic in a wide wavelength range as shown in these.

The carbon nanotubes contained in the carbon nanotube-containing layer 16C are preferably open-end carbon nanotubes whose ends are decorated with carboxyl groups or hydroxyl groups. Open-end carbon nanotubes whose ends are decorated with carboxyl groups or hydroxyl groups are easy to disperse in a solvent, so that it is possible to form a layer 16C containing carbon nanotubes in which carbon nanotubes are uniformly dispersed.
The carbon nanotubes contained in the layer 16C containing carbon nanotubes are preferably single-walled carbon nanotubes (SWCNT).
Furthermore, the thickness of the layer 16C containing carbon nanotubes is preferably 0.1 μm or more and 50 μm or less.

As shown in FIG. 2, the SiO ₂ film 16D is provided on the layer 16C containing carbon nanotubes.
The SiO ₂ film 16D has a size that covers the end surface 163B1 of the protrusion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161. That is, the SiO ₂ film 16D is larger than the planar shape of the layer 16C containing carbon nanotubes and covers the entire surface of the layer 16C containing carbon nanotubes. Further, the outer peripheral portion of the SiO ₂ film 16D is in contact with the outer peripheral portion of the antireflection film 16B.
Further, the SiO ₂ film 16D is also formed along the inclination of the end surface 163B1 of the projecting portion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161, and the end surface 163B1 of the projecting portion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161 It is almost parallel.

Although an antireflection film (not shown) is formed on the end face of the protrusion 151B of the ferrule 151 and the end face of the optical fiber 161 on the rear end side (half mirror module 14 side) in the light propagation direction, the carbon nanotube The layer 16C containing SiO ₂ and the SiO ₂ film 16D are not formed.

Such an optical fiber device 16 is manufactured as follows.
First, the pair of ends of the optical fiber 161 are inserted into the ferrules 163 and 151, respectively. At this time, the end face 163B1 of the projection 163B of the optical fiber 161 and the ferrule 163 is a vertical plane perpendicular to the optical axis of the optical fiber 161, and is not an inclined plane. Thereafter, the end surface 163B1 of the protrusion 163B of the ferrule 163 and the end surface of the optical fiber 161 are inclined surfaces inclined with respect to the optical axis of the optical fiber 161. Specifically, the end surface 163B1 of the protrusion 163B of the ferrule 163 and the end surface of the optical fiber 161 are tanned and polished to form an inclined surface.
Similarly, the end surface of the protrusion 151B of the ferrule 151 and the end surface of the end of the optical fiber 161 inserted into the ferrule 151 are also obliquely polished to form inclined surfaces.

Next, an antireflection film 16B is formed on the end face 163B1 of the protrusion 163B of the ferrule 163 and the end face 161A of the optical fiber 161. The antireflection film 16B can be formed by vacuum deposition.
Thereafter, a carbon nanotube-containing layer 16C is formed on the end surface 163B1 of the protrusion 163B of the ferrule 163 and the antireflection film 16B on the end surface 161A of the optical fiber 161.
First, carbon nanotubes are dispersed in a solvent and centrifuged. Here, the carbon nanotubes are dispersed in a solvent by ultrasonic waves.
Thereafter, the supernatant is extracted. The supernatant is centrifuged again and the supernatant is extracted again. After the centrifugation and the extraction of the supernatant are repeated a plurality of times, the supernatant is applied onto the antireflection film 16B.
Examples of the solvent in which the carbon nanotubes are dispersed include DMF (dimethylformamide), dichloroethane, alcohol, etc. Among them, it is preferable to use DMF.

When applying the supernatant on the antireflection film 16B, the supernatant is sprayed on the antireflection film 16B by a spray gun (application means), but heated toward the surface to be applied (that is, the surface of the antireflection film 16B). It is preferable to spray the supernatant while sending air. The direction in which the heated air is supplied is preferably a direction that substantially coincides with the direction in which the supernatant is sprayed by the spray gun.
Thus, the solvent can be reliably evaporated by forming the layer 16C containing carbon nanotubes while supplying heated air. When the solvent remains in the layer 16C containing the carbon nanotubes, the carbon nanotubes adhere to the solvent, and the carbon nanotubes are uneven in the layer 16C containing the carbon nanotubes.
On the other hand, in this embodiment, since the solvent can be reliably evaporated, the occurrence of unevenness of the carbon nanotubes can be prevented.

In the present embodiment, the carbon nanotube-containing layer 16C is not formed on the outer periphery of the antireflection film 16B.
In the present embodiment, a layer containing carbon nanotubes is selectively formed only in a portion corresponding to the upper portion of the end surface 161A of the optical fiber 161 (at least a portion covering the core of the optical fiber 161) in the antireflection film 16B. .
First, a mask that exposes a portion corresponding to the upper portion of the end surface 161A of the optical fiber 161 of the antireflection film 16B and covers the outer periphery of the antireflection film 16B is prepared. This mask is made of an aluminum plate, a SUS plate or the like, and has a hole in the center. When this mask is placed on the antireflection film 16B, the central portion of the antireflection film 16B (the portion corresponding to the upper portion of the end surface 161A of the optical fiber 161) is exposed from the hole of the mask.
Next, the dispersion liquid containing carbon nanotubes is sprayed with a spray gun.
Thus, by setting a mask such as an aluminum plate or a SUS plate on the antireflection film 16B, it is possible to prevent the layer 16C containing carbon nanotubes from being formed on the outer periphery of the antireflection film 16B. .
Further, after forming a layer containing carbon nanotubes on the entire surface of the antireflection film 16B with a spray gun, the outer peripheral portion of the layer containing carbon nanotubes may be shaved so that the outer peripheral portion of the antireflection film 16B is exposed. Good.
After forming the carbon nanotube-containing layer 16C as described above, the SiO ₂ film 16D is formed on the carbon nanotube-containing layer 16C.
The SiO ₂ film 16D can be formed by vacuum deposition.
The optical fiber device 16 can be obtained as described above.

Next, laser oscillation using the mode-locked optical fiber laser device 1 will be described.
When the mode-synchronous optical fiber laser device 1 is turned on and a current is applied to the excitation laser light source 11, the laser light is output and introduced into the WDM module 12. Then, this light is reflected by the WDM filter 122 and introduced into the optical amplifier 13 through the optical fiber device 15. In the optical amplifier 13, amplification is performed, and the amplified light is introduced into the half mirror module 14 through the optical fiber device 15. In the half mirror module 14, the half mirror 142 reflects part of the light and transmits the other part of the light. The reflected light is output as laser light through the optical fiber device 15.
On the other hand, the transmitted light is introduced into the WDM module 12 through the optical fiber device 16.
Here, when the mode-locked optical fiber laser device 1 is first turned on, the intensity of light circulating in the mode-locked optical fiber laser device 1 is weak, and unstable multimode oscillation is performed.
As the light circulates in the mode-locked optical fiber laser device 1, the intensity of the light increases. Then, when the power at which the saturable absorption characteristic of the carbon nanotube appears is reached, depending on the recovery time of the saturable absorption characteristic of the carbon nanotube, a mode-locked state is reached and a stable pulse oscillation state as shown in FIG. 5 is reached. .

The horizontal axis in FIG. 5 is time, and the vertical axis is the intensity of the output light. The pulse repetition time interval is 17.1 ns, and the repetition frequency is 58.35 MHz.
The center value of the oscillation wavelength is determined by the loss wavelength dependency of the component system of the mode-locked optical fiber laser device 1 and the gain wavelength dependency of the optical amplifier 13. As shown in FIG. 6, the center wavelength of the output spectrum is 1558 nm.
Further, as shown in FIG. 7, the pulse width of the waveform is 0.58 picoseconds.

Next, the effect of the mode-locked optical fiber laser device 1 will be described.
Since the end surface 161A of the optical fiber 161 of the optical fiber device 16 is an inclined surface inclined with respect to the optical axis of the optical fiber 161, the light incident on the end surface 161A of the optical fiber 161 is positive at the end surface 161A of the optical fiber 161. Does not reflect. That is, as shown in FIG. 2, since the reflected light L1 travels obliquely with respect to the optical axis X of the optical fiber 161, the reflected light L1 passes out of the core of the optical fiber 161. Therefore, return light can be prevented.
In addition, since the antireflection film 16B is formed on the end surface 161A of the optical fiber 161, reflection itself of the light incident on the end surface 161A of the optical fiber 161 can be reduced.

Furthermore, in the present embodiment, the antireflection film 16B, the carbon nanotube-containing layer 16C, and the SiO ₂ film 16D are formed along the end face 163B1 of the protrusion 163B of the ferrule 163 and the end face 161A of the optical fiber 161.
The interface between the antireflection film 16B and the carbon nanotube-containing layer 16C, the interface between the carbon nanotube-containing layer 16C and the SiO ₂ film 16D, and the outer surface of the SiO ₂ film 16D are all inclined surfaces. Therefore, the light emitted from the optical fiber 161 at the interface between the antireflection film 16B and the carbon nanotube-containing layer 16C, the interface between the carbon nanotube-containing layer 16C and the SiO ₂ film 16D, and the outer surface of the SiO ₂ film 16D. 2 and the reflected light L1 is generated, the reflected light L1 travels obliquely with respect to the optical axis X of the optical fiber 161, as shown in FIG. It will come out of the outside. Therefore, return light can be prevented.
Thereby, in this embodiment, return light can be reduced reliably and it can prevent reliably that the mode synchronization of the mode-synchronous optical fiber laser apparatus 1 breaks down.

Furthermore, in this embodiment, the return light from the end face 161A of the optical fiber 161, the interface between the antireflection film 16B and the layer 16C containing carbon nanotubes, the interface between the layer 16C containing carbon nanotubes and the SiO ₂ film 16D, SiO ₂ Since the return light from the outer surface of the film 16D can be reduced, it is possible to prevent the return lights from interfering with each other inside the optical fiber 161.
In the present embodiment, the angle formed by the end surface 163B1 of the protrusion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161 and the surface orthogonal to the optical axis X of the optical fiber 161 is 6 ° or more and 12 ° or less. Therefore, it is possible to reliably prevent the generation of return light.

In the present embodiment, the SiO ₂ film 16D is formed on the layer 16C containing carbon nanotubes. Since the SiO ₂ film 16D protects the carbon nanotube-containing layer 16C, it is possible to prevent the carbon nanotube from falling off the carbon nanotube-containing layer 16C.
Further, the SiO ₂ film 16D is not easily deteriorated by light emitted from the end face 161A of the optical fiber 161 and has high resistance, so that the performance of the mode-locked optical fiber laser device 1 is not deteriorated.

Furthermore, in this embodiment, the outer peripheral portion of the antireflection film 16B is not covered with the layer 16C containing carbon nanotubes, and the SiO ₂ film 16D provided on the outer peripheral portion of the antireflection film 16B and the layer 16C containing carbon nanotubes. Are in contact with each other. Since the antireflection film 16B is made of an inorganic material, the adhesion between the SiO ₂ film 16D and the antireflection film 16B is good. Therefore, the SiO ₂ film 16D is hardly peeled off, and the layer 16C containing carbon nanotubes can be reliably protected by the SiO ₂ film 16D.

  In this embodiment, when forming the layer 16C containing carbon nanotubes, the solvent in which the carbon nanotubes are dispersed is centrifuged, and then the supernatant is extracted, and this supernatant is applied. A layer 16C containing excellent carbon nanotubes can be formed. By centrifuging, it is possible to extract only carbon nanotubes having excellent saturable absorption characteristics.

  In this embodiment, since the polarization maintaining optical fiber is used as the optical fiber, the polarization state of the light propagated through the optical fiber can be maintained.

Further, in this embodiment, multiplexing and demultiplexing are performed using the WDM filter 122 and the half mirror 142 without using the optical fiber coupler.
When combining and demultiplexing using an optical fiber coupler, the spectrum as shown in FIG. 8 is shown, and when the WDM filter 122 and the half mirror 142 are used as in this embodiment ( Compared to FIG. 6), the ASE component (the bottom part of the spectrum) increases. Therefore, according to the present embodiment, it is possible to provide the mode-locked optical fiber laser device 1 with a small ASE component.
In addition, when performing multiplexing and demultiplexing using an optical fiber coupler, it is difficult to keep the extinction ratio high, but if a WDM filter 122 or a half mirror 142 is used as in this embodiment, It becomes possible to keep the extinction ratio high.

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIG.
In the embodiment, in the mode-locked optical fiber laser device 1, the WDM module 12, the optical amplifier 13, and the half mirror module 14 are connected in a ring shape by the optical fiber devices 15 and 16.
On the other hand, in this embodiment, a plurality of optical devices are arranged linearly.
Specifically, the mode-locked optical fiber laser device 2 of this embodiment includes an excitation laser light source 11 that supplies excitation light, a WDM module 22, and an optical amplifier that is supplied with excitation light from the excitation laser light source 11. 13, a polarizer 27, a half mirror unit 28, an isolator 29, and optical fiber devices 15 and 26.
In the mode-locked optical fiber laser device 2 of this embodiment, the right side of FIG. 9 is the light output direction.

The WDM module 22 includes a WDM filter 122, a mirror 223, and a housing 224 that accommodates these.
An antireflection film (not shown) is formed on the surface of the WDM filter 122 opposite to the excitation laser light source 11.
The mirror 223 is for reflecting the light transmitted through the WDM filter 122, and is disposed on the rear side of the light output direction with respect to the WDM filter 122.
An optical amplifier 13 similar to that of the above-described embodiment is installed at the front end side of the WDM module 22 in the light output direction. The WDM module 22 and the optical amplifier 13 are connected by the optical fiber device 15 as in the above embodiment.

Further, a polarizer 27 and a half mirror unit 28 are installed on the front end side of the optical amplifier 13 in the light output direction.
The optical amplifier 13, the polarizer 27, and the half mirror unit 28 are connected by an optical fiber device 26.

As shown in FIG. 10, the optical fiber device 26 includes an optical fiber 161, a ferrule 163, a collimator lens L, and a housing 164 that are the same as those in the above embodiment.
One end of the optical fiber 161 is connected to the optical amplifier 13, and the other end is inserted into the ferrule 163.

Unlike the above embodiment, an optical filter 26B is provided on the end surface 163B1 of the protrusion 163B of the ferrule 163 of the optical fiber device 26 and the end surface 161A of the optical fiber 161 as shown in FIG.
The optical filter 26B reflects light in the vicinity of 980 nm (that is, light having the same wavelength as the light from the excitation laser light source 11) and light in the vicinity of 1550 nm (that is, light having the same wavelength as that amplified by the optical amplifier 13). Light). The optical filter 26B covers the entire end surface 163B1 of the protrusion 163B of the ferrule 163 and the entire end surface 161A of the optical fiber 161, and along the inclination of the end surface 163B1 of the protrusion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161. The end surface 163B1 and the end surface 161A are provided substantially in parallel.
Here, examples of the optical filter 26B include a laminate of a SiO ₂ film and a TaO ₅ film.

  A layer 26C containing carbon nanotubes is provided on the optical filter 26B. The plane size of the carbon nanotube-containing layer 16C of the above embodiment is smaller than the plane size constituted by the end face 163B1 of the protrusion 163B of the ferrule 163 and the end face 161A of the optical fiber 161. The size of the plane 26C of the layer 26C containing the carbon nanotubes is equal to the size of the plane constituted by the end face 163B1 of the protrusion 163B of the ferrule 163 and the end face 161A of the optical fiber 161, and the end face 163B1 of the protrusion 163B of the ferrule 163 And the entire end surface 161A of the optical fiber 161 is covered. In other respects, the layer 26C containing carbon nanotubes is the same as the layer 16C containing carbon nanotubes of the above embodiment.

The collimator lens L is disposed on the front end side in the light output direction with respect to the ferrule 163. The collimator lens L allows the light from the optical fiber 161 to enter the polarizer 27 as parallel light and is disposed on the front end side in the light output direction of the polarizer 27. The light reflected by the mirror 281 is collected and guided into the optical fiber 161.
The manufacturing method of such an optical fiber device 26 is substantially the same as that of the above embodiment, except that the optical filter 26B is formed on the end surface 161A of the optical fiber 161 and the end surface 163B1 of the protruding portion 163B of the ferrule 163, carbon nanotubes Only the point that the layer 26C containing carbon nanotubes is formed on the entire surface of the optical filter 26B when the layer 26C containing is different from the above embodiment.

The half mirror unit 28 reflects a part of the light from the polarizer 27 and transmits the other part of the light. The transmitted light is introduced into the isolator 29 and output through the optical fiber device 15.
The half mirror unit 28 reflects a part of the light from the polarizer 27 and transmits the other part of the light from the polarizer 27, and the half mirror 281 is fixed to one light transmission surface. And the antireflection film 283 attached to the other light transmission surface of the transparent substrate 282.
One light transmission surface of the transparent substrate 282 is a vertical surface perpendicular to the optical axis of the mode-locked optical fiber laser device 2, but the other light transmission surface of the transparent substrate 282 is a mode-locked optical fiber laser device. The inclined surface is inclined with respect to the optical axis 2. An antireflection film 283 is attached to the inclined surface. Thus, by forming the antireflection film 283 on the inclined surface, generation of reflected light can be reliably suppressed.
Although the other light transmitting surface of the transparent substrate 282 is an inclined surface here, the present invention is not limited to this, and the other light transmitting surface of the transparent substrate 282 is perpendicular to the optical axis of the mode-locked optical fiber laser device 2. It may be a vertical surface.

Next, laser oscillation using the mode-locked optical fiber laser device 2 will be described.
First, when the power of the mode-synchronous optical fiber laser device 2 is turned on and a current is applied to the excitation laser light source 11, laser light is output and introduced into the WDM module 22. The light introduced into the WDM module 22 is reflected by the WDM filter 122 and introduced into the optical amplifier 13 via the optical fiber device 15. In the optical amplifier 13, amplification is performed, and the amplified light is introduced into the polarizer 27 and further into the half mirror unit 28 through the optical fiber device 26. The half mirror 281 of the half mirror unit 28 reflects a part of light and transmits another part of light. The light transmitted through the half mirror 281 is taken out from the optical fiber device 15 through the isolator 29.
On the other hand, the light reflected by the half mirror 281 returns into the optical fiber device 26 and is introduced into the WDM module 22 via the optical amplifier 13 and the optical fiber device 15. The light introduced into the WDM module 22 passes through the WDM filter 122 and is reflected by the mirror 223 toward the light output direction. The light reflected by the mirror 223 passes through the WDM filter 122 and is introduced into the half mirror unit 28 via the optical fiber device 15, the optical amplifier 13, the optical fiber device 26, and the polarizer 27.
Thus, in the present embodiment, resonance is performed between the half mirror 281 of the half mirror unit 28 and the mirror 223 of the WDM module 22.
Initially when the mode-locked optical fiber laser device 2 is turned on, since the intensity of light is weak, unstable multimode oscillation occurs, but the light is half mirrored by the half mirror unit 28 of the mode-locked optical fiber laser device 2. When the light intensity increases as it moves between 281 and the mirror 223 of the WDM module 22 and reaches the power at which the saturable absorption characteristic of the carbon nanotube appears, a mode-locked state is established.

Such a mode-locked optical fiber laser device 2 can achieve the same effects as the mode-locked optical fiber laser device 1 of the above-described embodiment, and can also provide the following effects.
On the end surface 163B1 of the protrusion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161 of the optical fiber device 26 of the mode-locked optical fiber laser device 2, the light that reflects light near 980 nm and transmits light near 1550 nm A layer 26C containing carbon nanotubes is provided through the filter 26B.
Here, the light output from the optical amplifier 13 is light in the vicinity of 1550 nm, but the light in the vicinity of 980 nm may be mixed with part of the light output from the optical amplifier 13. Since the light in the vicinity of 980 nm is light emitted from the excitation laser light source 11, the light has very high intensity. When this high intensity light is incident on the carbon nanotube-containing layer 26C, the carbon nanotube-containing layer 26C may be deteriorated or the saturable characteristic may be saturated.
In the present embodiment, the optical filter 26B is provided to reflect light near 980 nm and prevent light near 980 nm from entering the carbon nanotube-containing layer 26C. Deterioration of 26C can be prevented.
In addition, since light near 980 nm is prevented from entering the layer 26C containing carbon nanotubes, saturation of the saturable characteristics of the layer 26C containing carbon nanotubes can be prevented.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above embodiments, the carbon nanotubes in the layer containing carbon nanotubes are open-end carbon nanotubes whose ends are decorated with carboxyl groups and hydroxyl groups. However, the present invention is not limited to this. Carbon nanotubes whose ends are closed may be used.

Further, in each of the above embodiments, the optical fiber is a polarization maintaining optical fiber, but it may not be a polarization maintaining optical fiber. For example, a polarization plane controller or the like may be provided in the optical fiber device without using the optical fiber as a polarization maintaining optical fiber.
Moreover, in each said embodiment, although the angle which the end surface 161A of the optical fiber 161 of an optical fiber apparatus makes and the surface orthogonal to the optical axis of the said optical fiber was 6 degrees or more, not only this but the said, The angle can be set as appropriate.

  Furthermore, in each said embodiment, although the layer containing a carbon nanotube did not contain a binder material, it is good also as a thing containing a binder material not only this but the layer containing a carbon nanotube. For example, a binder material composed of an ultraviolet curable resin, a polyimide resin, a PVA resin, or the like may be included to prevent the carbon nanotubes from falling off.

  In the first embodiment, when spraying the dispersion containing carbon nanotubes with a spray gun, a mask such as an aluminum plate or a SUS plate with a hole in the center is installed on the antireflection film 16B. By covering the outer periphery of the antireflection film 16B, the formation of a layer containing carbon nanotubes on the outer periphery of the antireflection film 16B is prevented. However, the present invention is not limited to this. For example, the center on the antireflection film 16B The dispersion liquid may be dropped onto the portion corresponding to the upper side of the end surface 161A of the optical fiber 161 so that the dispersion liquid does not spread to the outer peripheral portion of the antireflection film 16B. If the dispersion liquid is dropped and spread in this way, the amount of the dispersion liquid to be used can be reduced as compared with the method of spraying the dispersion liquid with a spray gun. Thereby, it becomes possible to reduce the usage-amount of a carbon nanotube, and can aim at reduction of cost.

Further, in the first embodiment, carbon nanotubes are contained on the end surface 161A of the optical fiber 161 of the optical fiber device 16 that connects the half mirror module 14 and the WDM module 12 and the end surface 163B1 of the protruding portion 163B of the ferrule 163. However, the present invention is not limited to this, and the optical fiber device 15 disposed between the WDM module 12 and the optical amplifier 13 and the optical fiber device disposed between the optical amplifier 13 and the half mirror module 14 are not limited thereto. 15. The end face of the protruding portion of the optical fiber device 15 for outputting the light reflected by the half mirror module 14 and the end face of the optical fiber are the same as the end face 163B1 of the protruding portion 163B of the ferrule 163 and the end face 161A of the optical fiber 161. An inclined surface, and carbon nanochu on this inclined surface It may form a layer containing.
Further, also in the second embodiment, the end face of the protruding portion of the ferrule of the optical fiber device 15 arranged between the WDM module 22 and the optical amplifier 13 or the optical fiber device 15 connected to the isolator 29 and the light The fiber end surface may be an inclined surface similar to the end surface 163B1 of the protrusion 163B of the ferrule 163 and the end surface 161A of the optical fiber 161, and a layer containing carbon nanotubes may be formed on the inclined surface.
However, when light from the excitation laser light source 11 directly hits the layer containing the carbon nanotube, the layer containing the carbon nanotube may be deteriorated, or the saturable characteristic of the layer containing the carbon nanotube may be saturated. This may cause noise to pass through the layer containing carbon nanotubes.
Therefore, it is desirable to form a layer containing carbon nanotubes on the end face of the protruding portion of the optical fiber of the optical fiber device 15 disposed on the front side of the optical output direction with respect to the optical amplifier 13.

In the first embodiment, the carbon nanotube-containing layer 16C is formed on the antireflection film. However, the present invention is not limited to this, and the antireflection film may be formed on the carbon nanotube-containing layer 16C.
For example, the carbon nanotube-containing layer 16C is formed directly on the end face 163B1 of the protrusion 163B of the ferrule 163 and the end face 161A of the optical fiber 161. At this time, the outer peripheral portion of the end face 163B1 of the protrusion 163B of the ferrule 163 is not covered with the layer 16C containing carbon nanotubes. Then, an antireflection film may be formed so as to cover the layer 16C containing carbon nanotubes, and the outer peripheral portion of the antireflection film and the outer peripheral portion of the end surface 163B1 of the protruding portion 163B of the ferrule 163 may be in contact with each other.
Furthermore, in each said embodiment, you may form only the layer containing a carbon nanotube on the end surface 161A of the optical fiber 161 at least, without providing an antireflection film, a protective film, and an optical filter.

Further, in the second embodiment, the optical fiber device 26 includes the optical filter 26B that reflects light near 980 nm and transmits light near 1550 nm. A similar optical filter may also be provided on the end face 163B1 of the protruding portion 163B of the optical fiber 161.
Furthermore, the layer containing the carbon nanotubes of the second embodiment is provided so as to cover the entire end surface 163B1 of the protruding portion 163B of the ferrule 163 and the entire end surface 161A of the optical fiber 161. However, the present invention is not limited to this. It is good also as what does not cover the outer peripheral part of end surface 163B1 of this protrusion part 163B.

Further, the optical filter of the second embodiment is provided so as to cover the entire end surface 163B1 of the protrusion 163B of the ferrule 163 and the entire end surface 161A of the optical fiber 161. However, the present invention is not limited to this, and the protrusion 163B of the ferrule 163 is provided. It is good also as what does not cover the outer peripheral part of end surface 163B1.
Further, in each of the embodiments, the optical amplifier 13 has a rare earth-doped optical fiber. However, the optical amplifier 13 may have a semiconductor optical amplifier as an optical amplifier.

In addition, the arrangement of the optical devices such as the excitation laser light source 11, the optical amplifier 13, and the optical fiber devices 15, 16, and 26 shown in the above embodiments is an example, and is not limited to the above embodiments. For example, as shown in FIG. 11, an optical device may be arranged. In FIG. 11, the WDM filter 122 is arranged on the front side in the light propagation direction with respect to the optical amplifier 13. Light from the excitation laser light source 11 is reflected by the WDM filter 122 and enters the optical fiber device 15 disposed between the optical amplifier 13 and the WDM filter 122. Thereafter, the light enters the optical amplifier 13 and the optical amplifier 13 performs amplification. The amplified light again enters the optical fiber device 15 disposed between the optical amplifier 13 and the WDM filter 122. The light passes through the WDM filter 122 and the isolator 141, and a part of the light is reflected by the half mirror 142. The reflected light is output as laser light through the optical fiber device 15.
On the other hand, the transmitted light enters the isolator 121 through the optical fiber device 16. The light from the isolator 121 enters the optical fiber device 15 and enters the optical amplifier 13 again.

Further, in each of the above embodiments, the optical fiber 152 of the optical fiber device 15 and the optical fiber 161 of the optical fiber device 26 are connected to both ends of the rare earth-doped optical fiber of the optical amplifier 13. The ferrule 151 or the ferrule 163 may be directly attached to both ends of the rare earth-doped optical fiber of the optical amplifier 13.
In this way, the resonator length of the mode-locked optical fiber laser device can be shortened, and the repetition frequency can be increased.
The optical fiber 161 of the optical fiber device 16 and the optical fiber 161 of the optical fiber device 26 may be rare earth-doped optical fibers.

It is a schematic diagram which shows the mode-locking optical fiber laser apparatus concerning 1st embodiment. It is a schematic diagram which shows the principal part of an optical fiber apparatus. It is a perspective view which shows the relationship between the anti-reflective film of an optical fiber device, and the layer containing a carbon nanotube. It is a figure which shows the saturable absorption characteristic of a carbon nanotube. It is a figure which shows the mode of the pulse oscillation of a mode synchronous optical fiber laser apparatus. It is a figure which shows the relationship between the intensity | strength of the light output from the mode synchronous optical fiber laser apparatus, and a wavelength. It is a figure which shows the autocorrelation waveform of the light output from the mode-locking optical fiber laser apparatus. It is a figure which shows the relationship between the intensity | strength of the light output from the mode-locking optical fiber laser apparatus using an optical fiber coupler, and a wavelength. It is a schematic diagram of the mode synchronous optical fiber laser apparatus concerning 2nd embodiment. It is a figure which shows the principal part of an optical fiber apparatus. It is a schematic diagram of the mode synchronous optical fiber laser apparatus concerning the modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mode-locking optical fiber laser apparatus 2 Mode-locking optical fiber laser apparatus 11 Excitation laser light source 12 WDM module 13 Optical amplifier 14 Half mirror module 15 Optical fiber apparatus 16 Optical fiber apparatus 16B Antireflection film 16C Layer 16D containing carbon nanotube SiO ₂ films (protective film)
22 WDM module 26 optical fiber device 26B optical filter 26C layer containing carbon nanotube 27 polarizer 28 half mirror unit 29 isolator 121 isolator 122 filter 123 housing 141 isolator 142 half mirror 143 housing 151 ferrule 151A main body portion 151A1 large diameter portion 151A2 Small diameter portion 151B Protruding portion 152 Optical fiber 153 Housing 161 Optical fiber 161A End surface 163 Ferrule 163A Main body portion 163A1 Large diameter portion 163A2 Small diameter portion 163B Protruding portion 163B1 End surface 164 Housing 223 Mirror 224 Housing 281 Half mirror 282 Transparent substrate 283 Antireflection Film L Collimator lens L1 Reflected light X Optical axis θ Tilt angle

Claims (11)

An optical fiber, and a layer containing carbon nanotubes provided on an end face of the optical fiber,
The end surface of the optical fiber is an inclined surface inclined with respect to the optical axis of the optical fiber,
The optical fiber device, wherein the layer containing the carbon nanotubes is provided substantially parallel to the inclined surface. The optical fiber device according to claim 1,
An optical fiber device, wherein an angle formed by the inclined surface and a surface orthogonal to the optical axis of the optical fiber is 6 ° or more. The optical fiber device according to claim 1 or 2,
An optical fiber device, wherein an antireflection film is provided on an end face of the optical fiber. In the optical fiber device according to any one of claims 1 to 3,
An optical fiber device, wherein a protective film covering the layer containing carbon nanotubes is provided on the layer containing carbon nanotubes. The optical fiber device according to claim 4, wherein
Having a ferrule through which an end of the optical fiber is inserted;
The end surface of the ferrule and the end surface of the optical fiber are substantially on the same plane,
An antireflection film containing an inorganic substance is provided on the end face of the ferrule and the end face of the optical fiber,
A layer containing the carbon nanotube is provided on the antireflection film, and the protective film containing an inorganic substance is provided on the layer containing the carbon nanotube,
The outer periphery of the antireflection film is not covered with the carbon nanotube-containing layer,
The optical fiber device, wherein the protective film is in contact with an outer peripheral portion of the antireflection film. In the optical fiber device according to any one of claims 1 to 5,
The layer containing the carbon nanotubes contains the carbon nanotubes and a binder material. In the optical fiber device according to any one of claims 1 to 6,
2. The optical fiber device according to claim 1, wherein the carbon nanotube is an open-ended carbon nanotube whose end is decorated with at least one of a carboxyl group and a hydroxyl group. In the optical fiber device according to any one of claims 1 to 7,
The optical fiber device is configured by a polarization maintaining optical fiber. In the optical fiber device according to any one of claims 1 to 8,
On the end face of the optical fiber, there is provided a filter on which light amplified by an optical amplification medium excited by light from a laser light source is incident,
The filter reflects light emitted from the laser light source and transmits the amplified light.
An optical fiber device characterized in that a layer containing the carbon nanotube is provided on the light emitting side of the filter. Having a laser light source,
An optical amplification region to which light from the laser light source is supplied is formed,
A mode-locked optical fiber laser device that reintroduces a part of the light emitted from the light amplification region to the light amplification region and outputs another part of the light emitted from the light amplification region. ,
A mode-locked optical fiber laser device comprising the optical fiber device according to claim 1. A method of manufacturing an optical fiber device including an optical fiber,
A step of making the end surface of the optical fiber an inclined surface inclined with respect to the optical axis of the optical fiber;
Providing an end face of the optical fiber with a layer containing carbon nanotubes,
The step of providing the layer containing carbon nanotubes includes a step of dispersing the carbon nanotubes in a solvent, centrifuging, extracting the supernatant, and applying the supernatant onto the end face of the optical fiber. Manufacturing method.