JP2000353837A - Induced emission beam generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which generates a 1.4 μm band induced emission beam at high efficiency. SOLUTION: Reflectors 12 and 14 of 1.06 μm are arranged on both sides of an Nd-doped optical fiber 10, forming a resonator. An exciting LD16 generates a 0.8 μm band excitation beam. The 0.8 μm band excitation beam passes through the reflector 12 before coming into the fiber 10, and a part of it excites the Nd of the fiber 10, while a remaining part transmits the fiber 10 and the reflector 14 before entering a Tm-doped optical fiber 18, to excite the Tm of the optical fiber 18. Nd excited with the 0.8 μm band beam generates a 1.06 μm beam, and the resonator comprising the reflectors 12 and 14 causes laser oscillation. The 1.06 μm band laser beam passes through the reflector 14 and then enters the Tm-doped fiber 18, to excite the Tm contained in it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a stimulated emission light generator for generating stimulated emission light in a 1.4 μm band.

[0002]

2. Description of the Related Art An optical fiber in which Tm is added to a core is as follows.
By exciting with a 06 μm band Nd: YAG laser,
4 μm band stimulated emission light can be generated. By exciting an optical fiber doped with Tm and Ho with an LD of 0.8 μm band, stimulated emission light of 1.4 μm band can be generated.

[0003] Tm3 + ^{ions, 3} from the 3 _{F 4} level
Light is emitted in the 1.4 μm band due to the transition to the H ₄ level. However, since this transition is self-terminating, it is difficult to form a population inversion. Therefore, Tm
Even when excited by light of 0.8 μm band, which is a normal excitation wavelength of 3+ ions, stimulated emission light does not occur. Conventionally, the following method has been adopted to generate stimulated emission light in the 1.4 μm band.

The first method is a method in which an optical fiber in which Tm is added to a core is excited by a 1.06 μm band Nd: YAG laser. Here, Tm is excited in two stages. FIG.
Indicates a transition between energy levels of Tm. FIG.
As shown in, in the 1.06μm ^excitation, 3 _{H 6} →
³ H _{5 ^{Then,, 3 H 4 → 3 F}} 2 of Tm in two stages is ^excited, the transition of ³ _{F 4} → 3 H ₄ generates a 1.4μm band light. The reason for using the 1.06 μm band light is that this wavelength energy matches the energy of the ³ H ₄ → ³ F ₂ transition, and self-excitation is performed by re-exciting the ³ H ₄ level electrons using this transition. This is because terminating can be prevented.

[0005] A second method is a method in which an optical fiber doped with Tm and Ho is pumped by a 0.8 μm band LD. FIG.
Indicates the energy level and transition of the Tm-Ho system. In this method, self-terminating is prevented by transferring electrons at the ³ H ₄ level of Tm to the ⁵ I ₇ level of an adjacent Ho ion by energy transfer. 0.
The 8μm band optical, Tm is excited from ³ H ₆ to ³ F ^_4, for generating stimulated emission light of 1.4μm band transition from 3 _{F 4} to ³ H _4.

[0006]

In the above-described first method, the first-stage transition, that is, the transition from ³ H _{6 to} ³ H ₅ becomes a problem. This transition has low excitation efficiency because the energy is away from the 1.06 μm excitation wavelength. Therefore,
Total energy efficiency is also reduced. Further, since a solid-state laser is used as the excitation light source, the coupling efficiency between the excitation light and the Tm-doped optical fiber is low, and it is difficult to reduce the size of the device.

In the second method, a 2 μm
A lot of energy is lost by the emission of the band. That is, energy efficiency is poor.

An object of the present invention is to solve such a problem and to provide a stimulated emission light generating apparatus which generates 1.4 μm band stimulated emission light with high efficiency.

Another object of the present invention is to provide a 1.4 μm band stimulated emission light generating device which is excellent in energy efficiency and easy to miniaturize.

[0010]

According to the present invention, there is provided a stimulated emission light generating apparatus according to the present invention, which includes a light emitting medium to which Tm is added, an excitation light generating 0.8 μm band light and a 1.06 band light, and supplying the light to the light emitting medium. And a light source. By exciting Tm at two wavelengths of 0.8 μm band and 1.06 μm band,
1. Efficiently without self-terminating.
4 μm band light can be generated.

Preferably, the excitation light source is a 0.8 μm band light generator for generating 0.8 μm band light, and absorbs a part of the output light of the 0.8 μm band light generator to generate 1.06 μm band light. A 1.06 μm band light generator that generates and supplies the rest of the output light of the 0.8 μm band light generator together with the generated 1.06 μm band light to the light emitting medium.
Thus, it is sufficient to prepare a single light source, and it becomes compact and can be manufactured at low cost.

The 1.06 μm band light generating device is preferably
A 1.06 μm band light generating medium that is excited by 0.8 μm band light to generate 1.06 μm band light, and a 1.06 μm band light reflecting medium disposed on both sides of the 1.06 μm band light generating medium. A first reflector and a second reflector. As a result, high-intensity 1.06 μm light can be obtained.

1.06 μm excited by 0.8 μm band light
For example, Nd generates light emission.

[0014] The stimulated emission light generating device according to the present invention also includes:
An excitation light source that generates excitation light of a first wavelength, a first light emitting material that is excited by the excitation light of the first wavelength to generate light of a second wavelength, and light of the first wavelength And an optical transmission medium including a second light emitting material that is excited by the light of the second wavelength to generate light of the third wavelength, and the second wavelength disposed on both sides of the optical transmission medium. It is characterized by comprising first and second reflectors for reflecting light in a band.
Thus, the light of the third wavelength, which is the final object, can be efficiently generated from the excitation light of the first wavelength.
The whole can be made compact.

For example, the first light emitting material is Nd and the second light emitting material is Nd.
Is Tm. In addition, the first wavelength is 0.8 μm
The second wavelength belongs to the 1.06 μm band, and the third wavelength belongs to the 1.4 μm band.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing one embodiment of a 1.4 μm band stimulated emission light generating apparatus to which the present invention is applied.

Numeral 10 denotes an Nd-doped fiber, and reflectors 12 and 14 for reflecting light in the 1.6 μm band are connected to both ends thereof to form a resonator in the 1.06 μm band. Reflector 1
2, the reflectivity of the 1.06 μm band light is preferably 100%, while the reflectivity of the reflector 14 for the 1.06 μm band light is less than 100%.

On the opposite side of the reflector 12 from the Nd-doped fiber 10, an excitation LD (laser diode) 16 for generating excitation light for Nd is connected. That is, the output light of the pump LD 16 passes through the reflector 12 and enters the Nd-doped fiber 10. The wavelength of the pump LD 16 is Nd
Wavelength that can be excited to the ³ F ₂ level and, usually, a 0.8μm band.

A Tm-doped fiber 18 is connected to the reflector 14 on the side opposite to the Nd-doped fiber 10. The target 1.4 μm band stimulated emission light 20 is a Tm-doped fiber 1
8 is output from the end face opposite to the reflector 14.

In this embodiment, the Nd-doped fiber 10
The d concentration and length are set so that a part of the excitation light from the excitation LD 16 can be transmitted. The reflectors 12, 14
It is composed of an element that transmits 0.8 μm band light with low or no loss, for example, a fiber grating or a dielectric multilayer mirror. Therefore, 0.
A part of the 8 μm band excitation light passes through the reflector 12, the Nd-doped fiber 10, and the reflector 14, and
And excites Tm contained in the fiber 18.

The operation of this embodiment will be described. Excitation LD16
Is transmitted through the reflector 12 with low or no loss and enters the fiber 10. Its 0.
Part of the 8 μm band light excites the Nd-doped fiber 10,
A 1.06 μm band light is generated, and the rest passes through the fiber 10 and the reflector 14 and is incident on the Tm-doped fiber 18.
The Tm of the Tm-doped fiber 18 is excited. The 1.06 μm band light generated in the Nd-doped fiber 10 is reflected by the reflector 12,
The laser is confined by 14 and resonates to oscillate. N
The 1.06 μm band laser light generated in the d-doped fiber 10 passes through the reflector 14 and enters the Tm-doped fiber 18 to excite the Tm contained therein.

As a result, in this embodiment, the Tm-added
The Tm included in the fiber 18 is output from the excitation LD 16
0.8 μm band light and 0.8 μm output from pump LD 16
The Nd-doped fiber 10 is generated by being excited by the band light.
It will be excited by both 1.06 μm band light. 0.
8 μm band light is³H₆From³F₄Transition and energy
Since the Rugies match, Tm³H₆Level electrons
Efficiently³F₄It can be excited to a level. As explained earlier
To³F₄Level electrons are³H₄1.47 down to the level
It generates light in the μm band. The 1.06 μm band light is³H
₄From³F₂The transition to and the energy match
At Tm³H₄Efficient level electrons³F ₂Return to level
To excite. Self-terminating by this re-excitation
And the extremely efficient 1.4 μm band
Stimulated emission light is obtained.

That is, in this embodiment, the conventional 1.06 μm
The problem of pumping, that is, low pumping efficiency from the ³ H ₆ level, has been solved by using pump light in the 0.8 μm band together.
Further, in this embodiment, the energy loss due to the emission of Ho, which is a problem of the conventional method using the Tm-Ho doped fiber, is solved by using the 1.06 μm band light together.
Further, in the present embodiment, despite the two-wavelength excitation,
Since two wavelengths can be generated by one LD, it can be realized very compactly and at low cost.

The structure can be further simplified by adding Nd and Tm to the same fiber. FIG. 2 is a schematic block diagram showing the configuration of such an embodiment. 30 is Nd and Tm
, And reflectors 32 and 34 for reflecting light in the 1.06 μm band are connected to both ends of the fiber to form a 1.06 μm fiber.
A resonator of the band light is formed. 1. Reflectors 32 and 34
The reflectivity of the 06 μm band light is preferably 100%.

A pump LD (laser diode) 36 for generating 0.8 μm band pump light is connected to the reflector 32 on the side opposite to the fiber 30. That is, the excitation LD
The output light 36 passes through the reflector 32 and enters the fiber 30.

The desired 1.4 μm band stimulated emission light 38 is generated in the fiber 30, passes through the reflector 34, and is output to the outside.

The Nd concentration of the fiber 30 depends on the pump LD 36
Absorbs part of the 0.8 μm band excitation light from
Is set to an extent that can be absorbed. The reflector 32
The reflector 30 is made of an element that transmits 0.8 μm band light with low loss or low loss, for example, a fiber grating or a dielectric multilayer mirror.
Any material that reflects light and can transmit light in the 1.4 μm band with low or no loss may be used.

The 0.8 μm band pumping light output from the pumping LD 36 is transmitted through the reflector 32 and passes through the Nd of the fiber 10.
And Tm. Nd of the fiber 30 is 0.8 μ
It is excited by m-band light and emits 1.06 μm band light. The generated 1.06 μm band light resonates in a resonator formed by the reflectors 32 and 34, and oscillates in a laser. This 1.06
The μm band laser light excites Tm in the fiber 30.

After all, similarly to the first embodiment, Tm is 0.8 μm band light output from the pumping LD 36 and 1.06 μm band where Nd is generated by being excited by the 0.8 μm band light output from the pumping LD 36. It will be excited by both light. Thereby, Tm stimulates and emits light in the 1.4 μm band with high efficiency.

Although Tm and Nd were added to the same fiber,
Similar effects can be obtained by serially connecting the Tm-doped fiber and the Tm-doped fiber.

Each of the above-described embodiments can be used, for example, in a device using optical amplification by stimulated emission such as a 1.4 μm band optical amplifier, a high-intensity light source, and a laser.

[0033]

As can be easily understood from the above description, according to the present invention, a 1.4 μm band stimulated emission light generation device with high efficiency, compactness and low cost can be realized. As a result, a highly efficient, compact and low-cost 1.4 μm
A band optical amplifier, laser, high-intensity light source, and the like can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention.

FIG. 2 is a schematic configuration block diagram of a second embodiment of the present invention.

FIG. 3 is a schematic diagram of energy levels and transitions of Tm.

FIG. 4 is a schematic diagram of energy levels and transitions of Tm and Ho.

[Explanation of symbols]

 10: Nd-doped fiber 12, 14: Reflector 16: Pump LD (laser diode) 18: Tm-doped fiber 20: 1.4 μm band stimulated emission light 30: Fiber 32, 34: Reflector 36: Pump light source 38: 1. 4μm stimulated emission light

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuya Nakai 2-1-1-15 Ohara, Kamifukuoka-shi, Saitama Pref. Inside Kadeidi Laboratories Co., Ltd. (72) Toshio Tani 2-1-1-15 Ohara, Kamifukuoka-shi, Saitama No. 5 F072 AB08 AK06 JJ01 JJ02 JJ08 KK07 PP07 RR01 YY15

Claims (7)

[Claims] 1. A stimulated emission light generating apparatus comprising: a light emitting medium to which Tm is added; and an excitation light source that generates 0.8 μm band light and 1.06 band light and supplies the light to the light emitting medium. 2. The 0.8 μm band light generating device, wherein the pumping light source generates 0.8 μm band light, and 1.06 μm band light by absorbing a part of output light of the 0.8 μm band light generating device. And a 1.06 μm band light generator for supplying the remaining output light of the 0.8 μm band light generator to the light emitting medium together with the generated 1.06 μm band light. Stimulated emission light generator. 3. The 1.06 μm band light generating device has an optical power of 0.1 μm.
A 1.06 μm band light generating medium that is excited by 8 μm band light to generate a 1.06 μm band light, and first and second 1.06 μm band light generating media disposed on both sides of the 1.06 μm band light generating medium. The stimulated emission light generating device according to claim 2, comprising a second reflector. 4. The 1.06 μm band light generating medium is Nd
The stimulated emission light generating device according to claim 3, comprising: 5. An excitation light source that generates excitation light of a first wavelength, a first light emitting material that is excited by the excitation light of the first wavelength to generate light of a second wavelength, and An optical transmission medium including a second light emitting material that is excited by the light of the first wavelength and the light of the second wavelength to generate light of the third wavelength; and disposed on both sides of the optical transmission medium. A stimulated emission light generator comprising: first and second reflectors for reflecting light in the second wavelength band. 6. The stimulated emission light generating device according to claim 5, wherein the first light emitting material is Nd, and the second light emitting material is Tm. 7. The first wavelength belongs to a 0.8 μm band,
The stimulated emission light generator according to claim 6, wherein the second wavelength belongs to a 1.06 µm band, and the third wavelength belongs to a 1.4 µm band.