JPS63316493A - Josephson laser - Google Patents

Abstract

PURPOSE:To apply laminated superconducting materials to optical communication and optical computers by laminating superconducting material and insulating material, impressing a voltage on the superconducting material, and discharging photons from laminating interfaces. CONSTITUTION:A voltage is impressed from a voltage source 3 on materials where an oxidizing insulation layer 1 and a superconducting layer 2 are laminated alternately. The voltage V impressed between laminated materials discharges photons having oscillation frequencies omega. As to the frequency of a high frequency current passing through a laminating interface, it becomes the high frequency current of a micro wave band in cases where V is muV order and further, infrared, visible radiation, ultraviolet, X-and gamma-rays are discharged from laminating interfaces in cases where V is increased. In this way, lights or X-and gamma-rays having optional frequencies can be generated by laminating superconductors and insulators and by impressing a voltage on the laminated materials and then, their outputs are so high that such laminated materials can be used to high output, modulated laser and further, they are applicable for optical switches, magnetic switches as well as optical communication systems.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is based on a method of laminating a superconducting material and an insulating material, applying a voltage to the superconducting material, and emitting photons from the laminated interface. Son lasers are suitable for optical communications and optical computers.

[Conventional technology]

Conventionally, GaAs gr was used as a material for compound lasers.
A compound semiconductor such as nP is used, and the optical output increases with the injection current, but exceeding 50 mW requires accurate control of the growth rate and degree of lattice mismatch, and the threshold current is about 10 mA. is discussed in Applied Physics Tutorial 56 Volume 3 No. 357-360.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take superconducting materials into consideration, requires lattice mismatch control, has a high threshold current, and has difficulty in achieving an optical output exceeding 50 mW.

An object of the present invention is to provide a Josephson laser with a low threshold current.

[Means for solving problems]

The present invention resides in a Josephson laser characterized in that a VL layer is formed of a superconducting material and an insulating material, and photons are emitted from the laminated interface by applying a voltage to the superconducting material.

The above purpose is to combine the oxide insulating layer 1 and the superconducting WJ2 shown in FIG.
This is achieved by applying a voltage from the voltage source 3 to the material in which the superconducting layers are alternately laminated at a voltage lower than the Tc of the superconducting layer.

Let n be the Cooper pair concentration in the superconducting state, and the probability amplitude ψ of the Cooper pair is 'J' = fiV(!XP(i D )
・= (1). When the Cooper pair passes through the interface, the potential energy becomes -2 eV, so the potential energy in the stacked superconducting layers is eV, -e V , e V , -e V...
・It becomes. The probability amplitudes of these Cooper pairs ψl, ψ2.
The equation for...

It becomes t. The current from one superconducting layer to the next superconducting layer is (Jo
:/1 e n T), and the current oscillates at the frequency eV (5) ζ. Equation (5) indicates that when the Cooper pair passes through the insulating layer, it emits photons of ζω=2 eV.

That is, by changing V and emitting photons of an arbitrary frequency ω, if n is high, it can be applied as a laser.

[Effect]

The voltage V applied between the laminated materials emits photons of frequency ω, as shown in (5). From equation (5), the frequency of the high-frequency current passing through the interface has the characteristics shown in FIG. 2, and when V is on the order of μ■, it becomes a high-frequency current in the microwave band. Furthermore, when ■ increases, infrared rays, visible light,
Ultraviolet rays, X-rays, and γ-rays are emitted from the laminated interface.

〔Example〕

The present invention will be explained in detail below.

The laminated material of the oxide insulating layer and superconducting layer is made using the MBE method.

Manufactured by sputtering method. The manufacturing conditions are shown in Table 1.

Table 1 The vapor deposition sources used were BazYCuC)+ and KzMgFa.
type oxide. Since BazYCuOa, which is a superconducting material, is a transversely layered perovskite, a KzMgFi type oxide having almost the same lattice constant and structure was used for the insulating layer. When the film thickness of r3azY CIJO4 is 200 layers, the film thickness of the insulating layer is changed, and the total film thickness is 0.2 μm or more, the frequency Cf of the phonons emitted from the lamination interface is the third It became like the figure. dl<2
For 0 people, f is almost a constant value, but when dl > 20 people, as f decreases, the thickness of the insulating layer increases, and it becomes difficult to tunnel from the superconductor through the insulating layer. necessary,
The voltage may be low. Figure 3 shows the MBE in Table 1.
The frequency characteristics at liquid nitrogen temperature of a laminated film with a total film thickness of 0.3 μm produced under the following conditions are shown.

In the laminated film produced by the MBE method, f hardly decreases even when dl becomes 50 people, and it is thought that the tunnel current between the superconducting layer and the insulating layer flows stably.

B a 2 Cu O 4 produced under the MBE conditions shown in Table 1
A stacked film of 5rzTiOa and 5rzTiOa exhibited a light output of about 700 mW at liquid nitrogen temperature when d+=10 people. Further, the laser light output remained almost constant even when dl was increased up to 50 people, as shown in FIG.

〔Effect of the invention〕

According to the present invention, a superconductor and an insulator are laminated.

It can generate light, X-rays, and γ-rays with any frequency by applying a voltage, and its output is high, so it can be applied as a high-output, modulated laser. moreover.

It has potential applications in optical switches, magnetic switches, and optical communications in superconducting circuits.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the film structure of the Josephson laser of the present invention, and FIG. 2 is a diagram showing the relationship between frequency and applied voltage.
FIG. 3 is a diagram showing the relationship between frequency and current, and FIG. 4 is a diagram showing the relationship between optical output and current.

Claims (1)

[Claims] 1. A Josephson laser characterized by laminating a superconducting material and an insulating material and emitting photons from the laminated interface by applying a voltage to the superconducting material. 2. A Josephson laser according to claim 1, characterized in that a layered perovskite oxide is used as the superconducting material, and a perovskite oxide is used as the insulating material.