RU2351045C1 - Solid maser on conduction electrons - Google Patents

Abstract

FIELD: physics, radio.

SUBSTANCE: invention pertains to quantum radiophysics, and more specifically to solid laser beam generators, generating signals in millimeter and sub-millimeter ranges (30 GHz - 1500 GHz) and can be used in radio spectroscopy, in communication technology, in radio-astronomy and in detection and ranging, in biology and chemistry. The maser comprises an active element and injector, adjoining each other with their contact surfaces, having unevenness of not more than 1 mcm. On each surface opposite the contact surface, is fixed the corresponding current lead. Active element is made in the form of a lamel from mono-crystals of indium antimonide, thickness 0.5 mm - 1 mm, carrier concentration in it is 10¹⁴-10¹⁵ cm^-3. Injector is made in the form of a lamel from conductive ferromagnetic material with a high degree of spin polarization conduction electron with a resistivity of not more than 10^-2 O·cm, thickness 0.5 microns - 1 mm with the Curie temperature higher than the operating temperature.

EFFECT: range extension of radiation towards millimeter waves conserving the capability of radiation in sub-millimeter range due to the use of spin degree of freedom of injected electrons during range extension of operating temperatures towards higher temperatures.

7 cl, 2 dwg

Description

The invention relates to quantum radiophysics, and more particularly to solid-state quantum generators, and in particular to their low-frequency variety - masers generating signals in the millimeter and submillimeter ranges (30 - 1500 GHz), and can be used in physics, in particular for radio spectroscopy, for communication technologies, in radio astronomy and location, in biology, chemistry.

There is a problem of obtaining radiation in the millimeter and submillimeter range of electromagnetic waves, since lasers cannot emit in this range (wavelengths from tens of microns or less), and ordinary electrovacuum and semiconductor generators can no longer (wavelength - several millimeters or more) . Currently available fleet of generators capable of emitting in the millimeter and submillimeter ranges, there are units of devices. Millimeter-wave electro-vacuum devices, such as backward-wave lamps, do not allow frequency tuning, are bulky, and are not economical. Millimeter-wave semiconductor generators do not have the ability to smoothly change the frequency. The vast majority of masers emit only in the range of centimeter waves, have a small output power from 10 ^-10 to 10 ^-6 W, do not allow frequency tuning, work only at temperatures close to the temperature of liquid helium.

Any quantum generator or amplifier must have a spatially distinguished region (active region), in which, inevitably, an inverse population of the energy levels of any particles is artificially created periodically or continuously. The amplification of electromagnetic waves in the active region occurs due to forced particle transitions between energy levels with the emission of photons at a frequency determined by the difference in energy levels.

Several types of quantum generators are known: solid-state - on crystals or glasses, gas, semiconductor and quantum dye generators. Quantum generators are also subdivided into the types of particles that form the active medium. These can be molecules, atoms, ions and electrons (free or conduction electrons in a solid). Quantum generators are also subdivided according to the methods of inverting the population of levels (pumping) of the active medium. Quantum generators operating according to a three- or four-level scheme use optical pumping, gas-dynamic pumping, electric discharge pumping, and pumping with energy released as a result of chemical reactions. Quantum generators operating according to a two-level scheme use an external source of excited particles separated in space from the active region.

The present invention can be classified by type of quantum generators as solid-state masers, by type of particles as masers with conduction electrons, and by pumping method as masers with pumping used for two-level circuits, i.e. with an external source of particles creating an active medium.

A solid-state traveling wave device is known (RF Patent No. 2037916), amplifying vibrations in the millimeter wave range. The device is a rectangular elongated wafer of semiconductor having on the surface a system of transverse thin strips made also of a semiconductor or dielectric (waveguide structure), and also on the surface are two flat contacts located in front of and behind the waveguide structure, located on one straight line, perpendicular the direction of the stripes. The operation of the device is based on amplification of a wave propagating in a waveguide structure by electrons moving in a semiconductor with a drift velocity exceeding the wave velocity.

Since there are restrictions on the magnitude of the electric field that draws electrons, and therefore on the maximum speed of electrons, to achieve the maximum frequency, it is necessary to reduce the step of the periodic waveguide structure up to 1 μm. However, even with such a small step of the waveguide structure in a real device, the minimum length of the emitted electromagnetic wave was slightly less than 5 mm. Thus, the described device emits only at the beginning of the millimeter range and does not allow to obtain radiation in the entire range of millimeter waves and in the submillimeter range.

A known transistor microwave generator (RF Patent No. 2239938) with the claimed ability to generate second-harmonic oscillations with a frequency of over 100 GHz. The generator is constructed according to the Kolpitz scheme with the fundamental harmonic generation frequency specified by several concentrated and distributed capacitances and inductances, and a slot-waveguide resonator is included in the feedback at the second harmonic. The generator is a transistor, the three electrodes of which are connected to conductive surfaces located on a dielectric substrate, placed in a waveguide. One of the conductive surfaces is connected directly to the wide wall of the waveguide, and the other two are connected via blocking microstrip LC elements to the other wide wall of the waveguide. The gaps between the conducting surfaces together with the waveguide form waveguide-gap lines, the segments of which serve as waveguide-gap resonators.

The disadvantage of this generator is the need for precise matching of the location and size of several structural elements in resonance with the oscillations of the second harmonic. As a result of this, frequency tuning is not possible, and the minimum wavelength achieved by the real model was slightly less than 6 mm. Thus, the described device emits only at the beginning of the millimeter range and is not able to generate radiation in the entire range of millimeter waves and in the submillimeter range.

Known submillimeter silicon maser (RF Patent No. 2084996), excited using an additional infrared semiconductor laser based on GaAs. The maser is a parallelepiped made of n-Si, serving both as a resonator and an active element, a wide face of which is illuminated with laser light with a wavelength of 0.9 μm to create electron-hole pairs in silicon, and high voltage pulses are applied to opposite end faces. The radiation frequency is determined by the recombination energy of electrons and holes, i.e. Depends on the properties of the material and cannot be adjusted.

The disadvantage of a silicon maser is that such a maser is capable of generating radiation only at low temperatures (4.2 K <T <77 K) and requires a high-power semiconductor laser for excitation. Radiation occurs only at a single wavelength of 0.1 mm, and radiation at other wavelengths of the submillimeter and millimeter ranges cannot be obtained.

:Closest to the proposed invention is a solid-state cyclotron maser on conduction electrons (US Patent No. 4376917), generating oscillations at a frequency of 300 GHz - 30,000 GHz in the submillimeter range. A maser is a device containing two parts, both made of unalloyed or lightly doped semiconductor n-InSb (indium antimonide). Such doping corresponds to a carrier concentration of 10 ¹² -10 ¹³ cm ^-3 . The first part is the active element, made in the form of a disk with gold metallization of the end and side surfaces and is grounded. On one of the flat lateral surfaces of the active element in metallization, a round window is made for outputting radiation. On the opposite flat surface of the disk, metallization is made in the form of a lattice of thin concentric rings embedded in the body of the disk. The rings are connected to each other and to the rest of the metallization by thin jumpers. The second part of the maser, the injector, is designed to disperse conduction electrons and is made in the form of a hollow cylinder, one of the ends of which contacts the active element from the side of the lattice, and the opposite end is metallized and connected to the negative terminal of the current source. After the circuit is closed, the electrons in the injector accelerate and are injected through the metal lattice into the active element, in which they drift at a certain speed. In a magnetic field applied at a certain angle 0 <θ <π / 2 to the direction of electron drift, the electron motion acquires a spiral shape with an electron rotation speed Ω of the electrons in the spiral (Ω is the cyclotron frequency), and the kinetic energy of the electron motion along the spiral path acquires discrete values (quantized to Landau levels) with energy splitting levels

:

Ω = (qB ₀ ) / m,

where q is the electron charge;

V ₀ - external magnetic field;

m is the effective mass of the electron, in n-InSb m = 0.014m _0,

m ₀ - rest mass of an electron,

- постоянная Планка.

- Planck's constant.

Transitions from the highest Landau levels to the ground are accompanied by the emission of an electromagnetic wave at a frequency ω _c = SΩ, where S is an integer 1, 2, 3, etc.

However, a solid-state cyclotron maser has limitations on the maximum wavelength (or minimum frequency) that it is capable of emitting and the maximum temperature at which its operability is maintained. In a solid-state cyclotron maser, the kinetic motion of electrons along cyclotron orbits arising in a magnetic field is responsible for radiation. For a cyclotron (circular) orbit to occur, electrons must be able to rotate at least half a revolution, i.e. the condition Ω> 1 / τ _m should be satisfied, where τ _m is the relaxation time of the electron momentum or the time before the electron collides with any obstacle that changes its momentum. To fulfill these conditions, the temperature must be sufficiently low, since the frequency and amplitude of the atomic vibrations in the crystal, on collisions with which the electron momentum changes, depends on temperature. The magnetic field, on which the radiation frequency depends, on the contrary, should be high, since the radius of the electron’s circular orbit inversely depends on the magnitude of the magnetic field. In the well-known maser, the operating temperature cannot be higher than 77 K, and the magnetic fields should not be lower than a few kG, which corresponds to a minimum frequency of several hundred GHz. Thus, the real radiation range of a solid-state cyclotron maser covers only the middle and upper parts of the submillimeter range and does not reach the millimeter range due to disruption of the cyclotron maser’s operability with a decrease in the magnetic field.

The basis of the invention is the task of expanding the radiation range of the maser in the direction of millimeter waves while maintaining the possibility of radiation in the submillimeter range due to the use of spin degrees of freedom of the injected electrons while expanding the range of operating temperatures towards higher temperatures.

The problem is solved in that in a solid-state maser on conduction electrons, including an active element and an injector adjacent to each other by their contact surfaces, on each of the surfaces opposite the contact, a corresponding current supply is fixed, while the active element is made in the form of a plate of indium antimonide single crystal and its contact surface has a roughness of not more than 1 μm, according to the invention, the injector is made in the form of a plate of conductive ferromagnetic material with specific resistance of not more than 10 ^-2 Ohm · cm, a thickness of 0.5 μm - 1 mm and its contact surface also has a roughness of not more than 1 μm.

Wherein:

- materials with a high degree of spin polarization of conduction electrons, such as ferromagnetic semiconductors, semimetallic ferromagnets, ferromagnetic conductive manganites with a Curie temperature (T _C ) above the operating temperature, were used as a ferromagnetic material;

- Eu _0.98 Gd _0.02 O (T _C = 130 K), HgCr ₂ Se ₄ (T _C = 120-130 K) can be taken as ferromagnetic semiconductors;

- Heisler alloys Co ₂ MnSn (T _C = 826 K), Ni ₂ MnSn (T _C = 340 K), Co ₂ MnSb (T _C = 478 K) can be taken as semimetallic ferromagnets;

- La _0.8 Ba _0.2 MnO ₃ (T _C = 250 K), La _0.8 Si _0.2 MnO ₃ (T _C = 308 K) can be taken as ferromagnetic conducting manganites;

- the thickness of the active element is 0.5 - 1 mm, the concentration of carriers in it is 10 ¹⁴ -10 ¹⁵ cm ^-3 ;

- the contact surface of the active element is parallel to the crystalline plane (110) of indium antimonide.

The invention consists in the following.

To achieve this goal, a radiation formation mechanism was used, capable of operating in lower fields than the mechanism responsible for radiation in the prototype. It is known that the frequency of the spin resonance ω _s in the indium antimonide at the same magnetic field is almost three times lower than the cyclotron resonance frequency Ω, while the magnetic fields in which the transitions between spin levels occur can be significantly lower than the minimum magnetic fields, necessary for the formation of a cyclotron orbit in the prototype.

Spin is an analog of the mechanical moment of an elementary particle associated with its rotation around its own axis. If this particle is a negatively charged electron, then the rotation of such a charge around its own axis leads to the appearance of its own magnetic moment directed in the direction opposite to the mechanical moment (back). An external magnetic field interacts with the magnetic moments of the electrons and divides them into two groups of approximately equal numbers: with a magnetic moment directed across the field (lower Zeeman level) and against the field (upper Zeeman level). The transitions of electrons between levels change their energy - when moving from a lower level to an upper electron increases its energy (absorbs), and when moving from an upper to a lower one it can emit energy in the form of a quantum of electromagnetic energy. When transitions occur under the influence of a forcing electromagnetic field, they are called forced or stimulated transitions. The frequency ω _{s of} such a driving field is called the frequency of the spin resonance and is equal to the frequency of the quantum of electromagnetic energy emitted or absorbed by the electron during the transition.

where g is the conduction electron factor, in InSb g = -52,

µ _B - Bohr magneton,

- постоянная Планка.

- Planck's constant.

In this case, the ratio of the cyclotron resonance frequency (prototype) to the spin resonance frequency Ω / ω _s ≈ = 2.8.

The probability of forced transitions is the same for transitions from top to bottom and from bottom to top. Therefore, transitions occur from those levels at which there are more particles, and go on until the number of particles at the levels is equal. At finite temperatures in the natural state, at the lower level, the electrons are still slightly larger than at the upper, therefore, forced transitions are possible only from the lower to the upper level with energy absorption.

To obtain radiation during transitions between the Zeeman levels of conduction electrons in the active element, it is necessary to create a level population that is opposite to the natural one, i.e. make the population of the upper Zeeman levels larger than the lower ones (inverse population). In two-level systems, namely, such a system is formed by Zeeman levels of conduction electrons in the active element, inverse population can be created artificially only by delivering electrons from the outside to the upper level while electrons are evacuated from the lower level.

We found that the inverse population in an active element made of indium antimonide can be achieved by transporting spin-polarized electrons from an injector made of ferromagnetic materials capable of completely (or almost completely) polarizing the spin of a conduction electron due to the exchange interaction with the spin localized electrons responsible for ferromagnetism. (The spin direction of localized electrons at a temperature below the Curie temperature is opposite to the direction of the magnetic field.) Such materials include ferromagnetic semiconductors, semimetallic ferromagnets, and ferromagnetic conducting manganites. According to theoretical estimates, in materials of these classes at temperatures below the Curie temperature, 100% polarization of conduction electrons is possible. (In ordinary ferromagnetic metals, such as iron and nickel, the degree of polarization of conduction electrons does not exceed 10-20%.) Of the materials of these classes, those are used in which, at temperatures below the Curie temperature, the direction of polarization of the spin of conduction electrons coincides with the direction of the spin of localized electrons those. opposite to the direction of the magnetic field. We found that a number of materials possesses the indicated characteristics, in particular, EuO _0.98 Gd _0.02 O (T _C = 130 K), HgCr ₂ Se ₄ (T _C = 120-130 K), Co ₂ MnSn (T _C = 826 K), Ni ₂ MnSn (T _C = 340 K), Co ₂ MnSb (T _C = 478 K), La _0.8 Ba _0.2 MnO ₃ (T _C = 250 K), La _0.8 Sr _0.2 MnO ₃ (T _C = 308 TO).

The specified characteristic of the material of the injector in combination with the specific properties of the active element is used in the invention as follows. Usually, conduction electrons have a positive g-factor (g-factor is a value proportional to the gyromagnetic ratio of the electron). The positive sign of the g-factor for a negatively charged particle means that its spin and magnetic moment are directed in opposite directions. The indium antimonide from which the active element of the proposed maser is made is a material with an abnormal negative g-factor of conduction electrons. In such a material, the direction of the spin and the magnetic moment of the electron coincide. In an active element placed in an external magnetic field, in the equilibrium state (before the injection of spin-polarized electrons), conduction electrons are distributed over the Zeeman levels in accordance with Boltzmann statistics. In this case, most of the electrons with spin and magnetic moment directed along the field are at the lower levels, and a smaller part with the spin and magnetic moment opposite the field are at the upper levels.

We found that when electrons are injected from a material that polarizes spin into the n-InSb semiconductor, the direction of the electron spin is preserved, i.e. remains directed against the magnetic field. (In contrast to the electron momentum, which changes as a result of many electron collisions that occur during transport.) This phenomenon is based on the fundamental principle of conservation of angular momentum, an analog of which is spin. Since in n-InSb the upper Zeeman levels correspond to states with an electron spin directed opposite to the field, when electrons with spin also directed opposite to the field are transported from the injector to the active element, the upper Zeeman levels are filled and the lower levels are emptied, i.e. population inversion. This creates the conditions for the realization of radiation during transitions between these levels, i.e. conditions for achieving the task.

The radiation frequency, both in the prototype and in the proposed maser, is directly proportional to the magnitude of the magnetic field. However, with the same magnetic field in the indium antimonide, the frequency of the spin resonance is almost three times lower than the frequency of the cyclotron resonance (working frequency of the prototype). Moreover, the magnetic field itself, which sets the frequency of spin transitions, in the proposed device can be almost an order of magnitude smaller than the minimum magnetic field at which radiation in the prototype is possible. In the prototype, the minimum field is limited by the need to form an electron cyclotron orbit and is ₀ = 1.5-2 kG. In the proposed maser, the minimum field is determined from the condition that the coefficient of quantum gain of radiation exceeds the attenuation coefficient of the electromagnetic wave in the active element. Attenuation is inversely proportional to the square of the magnetic field. However, in the proposed maser, a high gain is achieved due to direct pumping of the upper Zeeman level by injection of electrons from a material with 100% polarization. As a result, the generation threshold was already reached in the fields B ₀ = 200-300 G.

Therefore, the use of spin degrees of freedom of the electron allows the proposed device to work in lower fields than the prototype can, and at the same time to obtain three times lower frequency in the same fields. Thus, the maximum wavelength can be increased by almost 30 times up to a few centimeters while maintaining the possibility of radiation in the submillimeter range, since the magnitude of the maximum magnetic field is unlimited.

The degree of inversion during electron transport is related to the magnitude of the polarization of electrons in the injector. The amplification characteristics of the active region are the higher, the greater the degree of inversion. Therefore, to achieve this goal, it is necessary to take materials with a maximum degree of electron polarization as the material for the manufacture of the injector.

The penetration depth of polarized electrons into the n-InSb plate determines the thickness of the active region and can range from a few micrometers to one millimeter depending on the current. To accomplish the task, the thickness of the active element is selected commensurate with or slightly greater than the thickness of the active region.

The active region is created by injection of electrons from the injector into the active element at the points of contact with the injector. To accomplish the task, it is necessary that the active region be continuous, and not in the form of islands that arise near the points of contact of the injector with the active element and surrounded by passive, absorbing material, the contact should be solid and dense. For this, the contact surfaces are made flat and smooth, with a roughness value of not more than 1 μm. For this, the contact surfaces of the injector and the active element must be combined. The size of the plate area of the active element is selected from design considerations, since it does not affect the performance of the proposed device.

The minimum thickness of the injector is determined by the thickness of the film of ferromagnetic material, which in order to achieve this goal must be known to be more than several hundred lattice periods so that its magnetic characteristics are close to those of bulk samples. The maximum thickness of the injector does not directly affect the operation of the device and is determined by considerations of the Joule heating of the device when an electric current flows through it. To reduce the Joule heating, it is necessary to use materials for the injector with a specific resistance of not more than 10 ^-2 Ohm · cm and not very thick, for example, 1 mm thick. With these parameters, a current of 10 A flowing for 10 μs causes the injector to heat less than one degree Kelvin.

The output power of the maser depends on the concentration of carriers in the active element: the higher the concentration, the more power can be achieved. However, at concentrations above 10 ¹⁵ cm ^–3 , the spin-spin relaxation time is shortened, the gain and, therefore, the output power decrease. Thus, the concentration of carriers in the active element from indium antimonide was selected 10 ¹⁴ -10 ¹⁵ cm ^-3 .

In a quantum generator (maser), electromagnetic radiation arises as a result of multiple amplification of its own spontaneous (noise) radiation. In the active element, it is necessary to create conditions for the effective interaction of the amplified electromagnetic wave with the electron. Such conditions are achieved when, during a forced transition, the electric component of the electromagnetic wave interacts with the electric dipole moment of the electron. The probability of electric dipole transitions is 10 ⁵ times higher than the probability of magnetic dipole transitions that occur, for example, in electron paramagnetic resonance. The electric dipole transitions with spin flip in InSb are realized upon magnetization of this material along the crystalline axis <110> (perpendicular to the plane (110) of the crystal). On the other hand, so that the penetration depth of electrons into the active element does not decrease due to the curvature of the trajectory of motion in a magnetic field, electrons must be sent to the active element along the magnetic field. Therefore, to achieve the task, the contact surface of the active element is parallel to the plane (110) of the crystal, and electrons are injected perpendicular to the plane of contact.

The maximum operating temperature of a quantum generator is determined by the competition of two processes: the upper-level pumping rate and the population leveling rate due to the thermal motion of the particles. The pump speed, both in the proposed device and in the prototype, is approximately the same and is determined by the magnitude of the current. The population leveling occurs during the pulse relaxation time τ _m (in the prototype) and during the spin relaxation time τ _s (in the proposed maser), which is usually much longer than the pulse relaxation time (in n-InSb, the ratio τ _s / τ _m can reach several orders of magnitude). Despite the fact that both times are shortened with increasing temperature, the ratio τ _s >> τ _m remains valid. Therefore, the proposed maser can operate at higher temperatures than the prototype. In the proposed maser, radiation was observed up to 200 K. The use of spin degrees of freedom of electrons provides an increase in the operating temperature by almost 3 times compared with the prototype, which expands the scope of the claimed maser and simplifies the conditions for its operation.

The invention is illustrated by drawings:

figure 1 - diagram of a solid state maser on conduction electrons;

figure 2 is a longitudinal section of the device.

A solid-state maser on conduction electrons is a contact structure consisting of an active element 1 and an injector 2. The active element 1 is made of a single crystal of indium antimonide semiconductor (n-InSb) with a carrier concentration of 10 ¹⁴ -10 ¹⁵ cm ^-3 and has the form of a plate with a thickness of 0.8 mm and an area of 2 × 2 mm ² . One of the wide sides of the plate is made flat and polished. The degree of roughness is not more than 1 μm. A layer of gold 3 is applied to the opposite side of the plate and the current contact 4 of the copper wire is soldered. The polished contact surface of the active element 1 should be parallel to the crystalline plane (110) of the indium antimonide semiconductor single crystal (n-InSb) of which the active element is made. Injector 2 - also has the shape of a plate and is made of a ferromagnetic material with a high degree of polarization of conduction electrons. The Heisler alloy Co ₂ MnSn (T _C = 826 K) was taken as the material for the injector. In addition, ferro-magnetic semiconductors EuO _0.98 Gd _0.02 O (T _C = 130 K), HgCr ₂ Se ₄ (T _C = 120-130 K) or Geisler alloys (semimetal ferromagnets) Ni ₂ MnSn (T _C = 340 K), Co ₂ MnSb (T _C = 478 K) or manganites La _0.8 Ba _0.2 MnO ₃ (T _C = 250 K), La _0.8 Si _0.2 MnO ₃ (T _C = 308 K). The resistivity of materials should not be more than 10 ^-2 Ohm · cm.

The injector 2 is approximately the same size, with the same preparation and the same polish. A gold layer 3 is also deposited on the surface opposite to the polished one and the current contact 4 is soldered. The polished surfaces of the active element 1 and injector 2 are densely pressed against each other along the normal of these surfaces using a special device (not shown).

The injector 2 from Geisler alloys can be obtained in the form of a film with a thickness of 0.5-1 μm deposited on the polished surface of the active element 1 from an indium antimonide semiconductor (n-InSb), for example, by thermal spraying in vacuum.

A solid state maser based on conduction electrons works as follows. A solid-state maser is located in the waveguide, for example, an 8-mm rectangular one, the contact plane of the active element 1 and injector 2 is parallel to the wide wall of the waveguide (not shown). The active element 1 by means of a current contact 4 is galvanically connected to the waveguide. A magnetic field of 450 G to 25 kG is applied perpendicular to the plane of contact along the direction of the <110> axis of the indium antimonide semiconductor (n-InSb). The device is cooled to a temperature of 180 K. (When using materials such as ferromagnetic semiconductors with a Curie temperature T _C = 120-130 K for the injector, the operating temperature must be lower than T _C. ) A negative potential of a current source, for example, a shaper, is applied to injector 2 current pulses of I = 0.5-10 A and a duration of 1-20 μs. Under the influence of the electric field created by the current pulse generator, spin-polarized electrons from the injector 2 are transported into the active element 1 to a depth of several units to hundreds of micrometers (depending on the magnitude of the electric field causing the current). In the active element, an active region is created under the entire contact area with a thickness equal to the penetration depth of electrons from the injector. The generation of radiation from the active region arises due to the amplification of intrinsic thermal noise, stimulating transitions between Zeeman levels of conduction electrons. Radiation in the form of packets of quanta with equally probable directions in the plane of contact of the active element 1 and injector 2 propagates parallel to this plane.

The radiation frequency f = ω _s / 2π, the wavelength λ = c / f,

where c is the speed of light.

The minimum magnetic field at which a solid-state maser operates on conduction electrons is determined by the competition of the quantum gain and attenuation of the electromagnetic wave in n-InSb and can be approximately estimated from the conditions of the generation threshold:

P = P ₀ exp [(k ₁ σIp-k ₂ / B ² ₀ ) L],

where k ₁ and k ₂ are the proportionality coefficients, P and P ₀ are the output and initial powers, p is the polarization coefficient p = (N ₂ -N ₁ ) / (N ₂ + N ₁ ), N ₂ and N ₁ are the population densities the upper and lower levels, respectively, I is the current, σ is the cross section of the forced transitions between the levels, L is the length of the active region, B ₀ is the external magnetic field.

In a solid-state maser at a current I = 1 A, lasing began in a field B ₀ ≈350 G, which corresponded to a wavelength of about one centimeter.

The initial power P _{0 of} thermal noise, the amplification of which causes generation, at T = 100 K is of the order of P ₀ ≈10 ^-12 W. When the output power in the millimeter range is P ₀ ≈ 10 ^-5 W, this corresponds to a gain of 10 ⁷ .

при 100% поляризации тока инжектируемых электронов (р=1), приведенная к величине тока для длин волн λ=8 мм и λ=0.1 мм, составляет 75 мкВт/А и 6 мВт/А соответственно.Ultimate Generation Power

at 100% polarization of the current of injected electrons (p = 1), reduced to the current value for wavelengths λ = 8 mm and λ = 0.1 mm, is 75 μW / A and 6 mW / A, respectively.

Spectral analysis of the radiation frequency in the millimeter wavelength range was carried out using pass-through resonators with known natural resonance frequencies and quality factor. Measurements showed that in fields with induction B ₀ 460, 530 and 700 G, electromagnetic radiation has a frequency f 33.4; 38 and 51 GHz, which corresponds to wavelengths of λ 9, 8 and 5.8 mm. The calculated wavelength λ in the field B ₀ = 23 kG is of the order of 0.018 mm. Thus, the maser emits in the millimeter wave range and preserves the possibility of radiation in the submillimeter range.

The magnetic field was measured in the range from 200 Gs to 23 kGs by a Hall sensor calibrated using a nuclear magnetometer.

Temperature was controlled and maintained in the range from 4.2 to 300 K using a helium pumping cryostat.

Temperature was measured in the range from 4.2 to 100 K using a germanium thermometer, and in the range from 70 to 300 K using a standard copper-constantan thermocouple.

The radiation was recorded in the temperature range from 4.2 to 200 K, when using Geisler alloys or manganites as an injector.

Thus, the operating temperature range was expanded from 77 K (prototype) to 200 K.

Claims (7)

1. A solid-state maser on conduction electrons, comprising an active element and an injector adjacent to each other by their contact surfaces, on each of the surfaces opposite to the contact, a corresponding current lead is fixed, while the active element is made in the form of a plate of indium antimonide single crystal, and its contact surface has a roughness of not more than 1 μm, characterized in that the injector is made in the form of a plate of conductive ferromagnetic material with a specific resistance of not more than 10 ^-2 Ohm · cm, a thickness of 0.5 μm - 1 mm and its contact surface also has a roughness of not more than 1 μm. 2. The maser according to claim 1, characterized in that a material with a high degree of spin polarization of conduction electrons, such as ferromagnetic semiconductors, semimetallic ferromagnets, ferromagnetic conductive manganites with a Curie temperature (T _c ) above the operating temperature, is used as a ferromagnetic material. 3. The maser according to claim 2, characterized in that EuO _0.98 Gd _0.02 O, HgCr ₂ Se ₄ can be taken as ferromagnetic semiconductors. 4. The maser according to claim 2, characterized in that Geisler alloys Co ₂ MnSn, Ni ₂ MnSn, Co ₂ MnSb can be taken as semimetallic ferromagnets. 5. The maser according to claim 2, characterized in that La _0.8 Ba _0.2 MnO ₃ , La _0.8 Si _0.2 MnO ₃ can be taken as ferromagnetic conductive manganites. 6. The maser according to claim 1, characterized in that the thickness of the active element is 0.5 mm - 1 mm, the concentration of carriers in it is 10 ¹⁴ - 10 ¹⁵ cm ^-3 . 7. The maser according to claim 1, characterized in that the contact surface of the active element is parallel to the crystalline plane (110) of indium antimonide.

Images