JPS63250878A - Superconducting laser - Google Patents

Abstract

PURPOSE:To inductively radiate a coherent electromagnetic wave and to gener ate the wave of high output by by forming a superconducting laser of a ceramic supercondactor material having a specific composition and many crystal grains. CONSTITUTION:A laser is formed of a ceramic superconductor material having a composition represented by a formula AaBbCc and many crystal grains. That is, a superconductor 2 having many crystal grains 1 is provided in an atmosphere cooled by liquid nitrogen, one end of a waveguide 3 is disposed near the superconductor 2, an electromagnetic wave having approx. 1mum of wavelength is irradiated from the other end, and a DC voltage 5 is applied in a direction perpendicular to the junction 4 of the superconductor 2. In the formula, A is an element selected from groups Ia, IIa and IIIa, B is an element selected from groups Ib, IIb and IIIb, and C is an element selected from oxygen, sulfur, carbon and nitrogen. Thus, an electromagnetic wave having high coher ence as a whole and large output can be irradiated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a superconducting laser, and more specifically, to a novel superconducting laser that generates coherent electromagnetic waves based on the grain boundary Josephson effect.

<Prior art and problems to be solved by the invention> Conventionally, lasers have been developed with a focus on their ability to generate light with high coherence, and they can be broadly classified into gas lasers, liquid lasers, and lasers. The practical application of solid-state lasers is progressing. Among solid-state lasers, research has been actively conducted on the development and practical application of semiconductor lasers, in particular, because they can be extremely miniaturized, pumped with electric current, and easy to handle. ing.

However, the output characteristics of semiconductor lasers not only vary significantly due to the influence of ambient temperature, but also due to self-oscillation that accompanies laser oscillation.
In order to obtain stable output characteristics, a heat sink, a cooler, etc. are required, and there is a problem in that the control of the semiconductor laser as a whole becomes complicated.

<Object of the Invention> The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a novel superconducting laser whose temperature can be easily controlled.

Means for Solving Problems> In order to achieve the above object, a superconducting laser of the present invention is made of a ceramic superconducting material having a composition represented by the following general formula (I), and has a large number of crystal grains. It is something that you have.

AaBbCc (I) (wherein A is at least one element selected from group Ia elements, group IIa elements, and group IIIa elements of the periodic table, and B is an element of group 1b of the periodic table, an element of group IIb, and at least one element selected from Group IIIb elements, and C is at least one element selected from oxygen, fluorine, sulfur, carbon, and nitrogen.) To explain in more detail, it constitutes a ceramic superconductor. As the raw material for the ceramic superconductor, any material containing the elements constituting the superconducting substance can be used in either the form of a single substance or a compound.

Examples of the above-mentioned elements include elements of Groups I, II, and III of the periodic table, as well as oxygen, nitrogen, fluorine, carbon, and sulfur.

More specifically, among Group I elements of the periodic table, Group Ia elements include Li%Nas K, Rb, Cs, etc.
Group Ib elements include Cu s A g 1 and Au
can be mentioned. Also, among the elements of group II of the periodic table, IIa
Group elements include B e , M g %Ca5Sr
, Ba, and Ra, and examples of group IIb elements include ZnSCd and the like.

Among the elements of group ■ of the periodic table, the elements of group ■a include S c
s Y and lanthanoid elements La and Ce.

A c sT, which is an actinide element such as Gd and Lu
h, Pa%Cf, etc. In addition, examples of the IIIb group element include Af, Gas Ins T'1, and the like.

Among the above elements, a ceramic superconductor comprising an element selected from group Ib elements, an element selected from group NA elements, group II a elements, and lanthanoid elements, and an element selected from oxygen and fluorine is preferable. Furthermore, Ib
Among the group elements, CusAg is preferred.

However, it is particularly preferable that B in the above general formula (I) is copper and C is oxygen.

In the above superconducting laser, many crystal grains are formed,
A thin barrier is formed between the grains.

And since each barrier acts as a junction,
When bombing electromagnetic waves are irradiated, stimulated emission of highly coherent electromagnetic waves occurs at each junction,
It has high coherence as a whole and can emit human-powered electromagnetic waves.

To explain in more detail, as shown in FIG. DC voltage [
A superconducting laser having a configuration in which electromagnetic waves for pumping are supplied to the device by applying F]) was manufactured.

The light emitting principle of this superconducting laser is as follows: ■The superconducting state below the critical temperature is completely conductive with zero electrical resistance, but the more basic property is that when a superconductor is placed in a magnetic field, the magnetic field becomes a superconductor. It does not penetrate into the interior and the magnetic flux density is always zero, that is, it exhibits perfect diamagnetism (Meissner effect). In this state, an attractive interaction acts between the two conduction electrons through lattice vibrations (phonons), and when the Coulomb repulsion is overcome, the energy gap Δ(0) where the two conduction electrons are bound to each other is It is given by equation [11].

Δ(0) = 1.78X k T c
(I) However, k is a constant determined by the element, and Tc is the critical temperature.

■ In the above superconducting state, when an electromagnetic wave exceeding the energy gap 2△, that is, an electromagnetic wave (pumping wave) with a frequency ν that can destroy the Cooper pair, is incident on the superconductor, the superconductor rapidly absorbs the electromagnetic energy hν. It has been experimentally confirmed that the energy level transitions to E2 (4th
(See Figure A).

■After a large number of electrons have transitioned to energy level E2, when the current flowing through the junction decreases and becomes less than the critical current, the electrons at energy level E2 will lose the energy of the superconducting state due to the Josephson effect. When transitioning to level E1, light is stimulated to be emitted and becomes coherent light with all phases aligned (see FIG. 4B).

Therefore, although it has the advantage that pumping can be performed by externally supplying an electromagnetic wave with a frequency ν that can destroy the Cooper pair, niobium (Nb) has a low critical temperature and is clear from the above formula (II). Since the amount of energy stored is small, the output of the generated laser light is weak, and by finely adjusting the contact area and contact pressure between the niobium plate (6) and the needle (7), the two superconducting Since a bonded state is formed in the body, there is a problem that the yield is very low.

In contrast, the superconducting laser of the present invention has a large number of crystal grain boundaries, and the wavelengths of the electromagnetic waves stimulated and emitted at each crystal grain boundary are all the same, so that the superconducting laser as a whole emits strong and highly coherent electromagnetic waves. can be released. Further, since it is only necessary to maintain the temperature condition below the critical temperature, temperature control can be simplified compared to a case where the temperature is maintained at a constant temperature, such as in a semiconductor laser.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a superconducting laser, in which a superconductor (2) having a large number of crystal grains (I) is provided in an atmosphere cooled with liquid nitrogen, and one end of a waveguide (3) is connected to the superconductor. (2)
At the same time, an electromagnetic wave with a wavelength of approximately 1 μm is irradiated from the other end, and a DC voltage (5) is applied in a direction perpendicular to the superconductor junction (4).

To explain in more detail, the superconductor (2) is made of an oxide superconductor and has a composition of 0.8 0.2 )2 CuO4.
Y Ba A sintered raw material for conductor is used.

When observed with X-rays, the superconductor (2) has a polycrystalline structure, and the thickness of the junction (4) is 2.
It is μm. And the critical temperature is 105 degrees, which is higher than the temperature of liquid nitrogen.

In order to generate coherent electromagnetic waves using the superconductor (2), the end of the waveguide (3) is drooped so that the electromagnetic waves are irradiated in a direction parallel to the junction (4) of the superconductor (2). Electromagnetic waves with a wavelength of 1 μm are irradiated from the other end of the waveguide (3). In this state, the superconductor (■ absorbs electromagnetic energy and the energy level becomes a high level. In other words, the superconductor (■) Each crystal grain (I) is irradiated with electromagnetic waves, the potential increases, and the current decreases.

When the current flowing between the crystal grains (I) becomes less than the critical current, it transitions to a lower energy level due to the Josephson effect, and coherent emission with the same phase occurs through stimulated emission from multiple junctions (4) one after another. It emits stimulated electromagnetic waves.

FIG. 2 shows another embodiment of the superconducting laser, and FIG.
Similar to the example, a superconductor (2) with a polycrystalline structure is placed in an atmosphere cooled by liquid nitrogen, and an electromagnetic wave with a wavelength of approximately 1 μm is guided through an optical fiber. ) is irradiated in the direction of junction (4). A DC voltage (5) is applied in a direction perpendicular to the junction (4).

In the case of this embodiment as well, as in the first embodiment, the superconductor (2) absorbs electromagnetic energy by irradiation with electromagnetic waves having a wavelength of 1 μl, and the energy level becomes a high level. Then, each crystal grain (I) of the superconductor (2) is irradiated with electromagnetic waves, so that the potential increases and the current decreases. Then, when the current drops below the critical current density, the Josephson effect causes a transition to a lower energy level, and stimulated emission of coherent electromagnetic waves with a uniform phase occurs.

In summary, by simply irradiating a superconductor with a polycrystalline structure with electromagnetic waves, pumping can be performed, and amplified coherent electromagnetic waves can be stimulated to be emitted due to the Josephson effect of the polycrystalline grain boundaries. . Therefore, the laser generation conditions for the superconducting laser need only be to regulate the ambient temperature to below the critical temperature, and the configuration can be simplified.

Furthermore, since the critical temperature is high, it can be cooled with liquid nitrogen and is easy to handle.

The present invention is not limited to the above-mentioned embodiments. For example, since electromagnetic waves with high coherence and large output can be easily obtained, it is possible to apply the present invention to excimer lasers. Various design changes can be made without changing the gist.

<Effects of the Invention> As described above, according to the superconducting laser of the present invention, since a superconductor having a polycrystalline structure is used, coherent electromagnetic waves are stimulated to be emitted from the junctions of a plurality of crystals, and the overall high performance is achieved. It can generate output electromagnetic waves. Furthermore, since there is no need for contact between the superconductors, a unique effect is achieved in that the configuration can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the superconducting laser of the present invention, FIG. 2 is a diagram showing another embodiment of the superconducting laser of the present invention, and FIG. 3 is a diagram illustrating a conventional superconducting laser. . FIG. 4 is a diagram explaining energy levels when laser oscillates. (I)...Crystal grain, 0n...Superconductor, (3
)...Waveguide, (4)...Junk shield,
(5)...DC voltage

Claims (1)

[Claims] 1. A superconducting laser comprising a ceramic superconductor material having a composition represented by the following general formula (I) and having a large number of crystal grains. AaBbCc (I) (wherein A is at least one element selected from group I a elements, group IIa elements, and group IIIa elements of the periodic table, and B is an element of group I b of the periodic table, group IIb elements) elements, and
(C is at least one element selected from Group IIIb elements, and C is at least one element selected from oxygen, fluorine, sulfur, carbon, and nitrogen.) 2. B in the above general formula (I) is copper. The superconducting laser according to claim 1, wherein C is oxygen.