RU213923U1 - Radiation Pumped Semiconductor Disk Laser Using a β-Radiation Source - Google Patents

Abstract

The utility model relates to laser technology, more specifically to semiconductor disk lasers pumped from a radioactive source, and can be used in communication systems, sensors and laser medicine. The essence of the proposed model for pumping a semiconductor laser is that a radioactive β-source Ni-63 is used as a pumping source, which ensures complete autonomy of the laser complex from external sources of electrical power. Known solid-state radioluminescent laser source based on a crystalline semiconductor homo - or heterostructures (Patent US 5561679, Mannik et al.). The energy diagram of this structure (the active element of the corresponding laser) has the form of one or more quantum wells (semiconductors with low and high band gaps alternate in the structure, such as GaAs and GaAlAs). The source itself is a vertical cavity surface emitting laser (VCSEL). This invention is taken as a prototype.

Description

The utility model relates to laser technology, more specifically to semiconductor disk lasers pumped from a radioactive source, and can be used in communication systems, sensors and laser medicine.

A known model of radioluminescence of solid-state laser materials activated by neodymium upon excitation by α-particles and fission fragments (E.A. Seregina, A.A. Seregin // Quantum Electronics, 43(2), pp. 150-156, 2013). The disadvantage of the known model is the need to use high-energy radiation.

Models are known for the creation of high-power nuclear-pumped lasers, in which the energy of nuclear fission is directly converted into the energy of laser radiation (A.A. Seregin, P.P. Dyachenko, V.I. Lapidus, E.A. Seregina // Quantum Electronics, 26(2), pp. 98-102, 1999). The disadvantages of this model are the low pumping efficiency, the short lifetime of the upper working level, and the high level of radiation.

A known model of radiation pumping using solid-state radioluminescent sources, in which the radioactive element is placed in an amorphous semiconductor (see US patent No. 5118951). Within the known model, β-radiation excites non-equilibrium electron-hole pairs, the recombination of which can emit light. The luminescence efficiency is determined by the ratio of radiative-recombining pairs to the total number of excited nonequilibrium electron-hole pairs. The rate of radiative recombination depends on the carrier lifetime and the recombination coefficient, which expresses for a given pair the probability of recombining radiatively.

A disadvantage of the known model is that amorphous semiconductors used as a material that provides the generation of electron-hole pairs have a short carrier lifetime (significantly less than 1 ns) and, as a result, a recombination coefficient lower than that of standard structures.

The essence of the proposed model for pumping a semiconductor laser is that a radioactive β-source is used as a pumping source, which ensures the complete autonomy of the laser complex from external sources of electrical power.

Known solid-state radioluminescent laser source based on a crystalline semiconductor homo - or heterostructures (Patent US 5561679, Mannik et al.). The energy diagram of this structure (the active element of the corresponding laser) has the form of one or more quantum wells (semiconductors with low and high bandgap levels alternate in the structure, such as GaAs and GaAlAs). The source itself is a vertical cavity surface emitting laser (VCSEL). This invention is taken as a prototype.

The disadvantages of this device are the low output power of less than 100 mW and the significant volatility of the radioactive source.

The essence of the proposed semiconductor laser lies in the fact that the laser is additionally equipped with a semiconductor structure based on quantum dots, which have a lower generation excitation threshold.

The use of the proposed device provides the following technical result: lowering the generation threshold and increasing the power of a semiconductor laser pumped from a radioactive element.

The peculiarity lies in the fact that a radioactive β-source is used as a pumping source, which ensures the complete autonomy of the laser complex from external sources of electrical power.

The device that implements the proposed model is a disk semiconductor laser with a vertical cavity with an external mirror.

The peculiarity lies in the fact that the laser is additionally equipped with a semiconductor structure based on quantum dots, which have a lower generation excitation threshold.

The analysis of the prior art carried out by the applicant, including searching through patents and scientific and technical sources of information and identifying sources containing information about analogues of the claimed utility model, made it possible to establish that the applicant did not find an analogue characterized by features identical to all essential features of the claimed utility model. The definition from the list of identified analogues of the prototype, as the analogue closest in terms of essential features, made it possible to identify a set of distinguishing features that are essential in relation to the technical result perceived by the applicant in the claimed utility model, set forth in the formula of the utility model.

Therefore, the claimed utility model meets the condition of "novelty".

In FIG. 1 shows a schematic representation of a semiconductor disk quantum dot laser and the energy level structure. The positions of FIG. one:

1 - external mirror;

2 - β-source, Ni-63;

3 - substrate;

4 - active area;

5 - mirror;

6 - window;

7 - barrier;

8 - quantum dots;

9 - separator.

In FIG. Figure 2 shows the structure of InAs quantum dots (0.5 ML - half a monolayer) in a GaAs matrix. The distance between quantum dots is 2.3 GaAs monolayers. The density is about 1011 quantum dots per cm2 ^.

The disk semiconductor laser (FIG. 1) is a VCSEL laser with an external mirror. The use of an external mirror makes it possible to increase the area of the active element and to use the intracavity mode locking technique with the help of a saturating absorber. This technique makes it possible to obtain significant peak pulse powers at a low average output radiation power. It is proposed to use a structure based on quantum dots as an active medium. In FIG. Figure 2 shows the structure of quantum dots obtained by the epitaxial method of submonolayer growth.

The proposed device works as follows.

The electrons emitted by the radioisotope source bombard the semiconductor heterostructure with the structure of quantum dots. In this case, quantum dots (in the region of their emission) are used as an active laser medium in the form of a quantum-sized structure that provides compression of electron-hole pairs by alternating a large number (potentially significantly more than 100) of semiconductor layers with different band gaps. This should lead to an increase in the efficiency of the corresponding lasers at room temperature. The use of quantum dots makes it possible to significantly reduce the pump power required to create a population inversion; reach the energy generation threshold, which is extremely important in the case of radioactive pumping, the power of which is limited by the activity of the radioactive source used. In addition, the use of quantum dots provides additional design advantages: by changing the size of the dots, it is possible to change the wavelength of the generated radiation; the structure of quantum dots is not so sensitive to temperature changes.

To create more gain, it is necessary to use a multilayer quantum dot structure with more than 100 layers.

As a radioactive pumping source, we propose to use not volatile tritium, but the β-active isotope Ni-63, obtained at the State Scientific Center of the Research Institute of Atomic Reactors (Dimitrovgrad). The energy spectrum of β-electrons of this radioisotope varies in the range from 0 to 66.7 keV, with an average energy of 17.1 keV. These energies make it possible to generate free carriers (about 3-5 thousand electron-hole pairs per β-particle), but they lie below the defect formation range and cannot lead to defects and destruction of the semiconductor crystal structure. Electrons of such energies cannot penetrate the skin layers and harm human health (Nagornov Y.S., Radchenko V.M., Pchelintceva E.S., Kostishko B.M., Risovany V.D., Materials of IV Russian seminar of fiber lasers, pp. 131-132, 2010). A film with a radionuclide is placed inside the body of a semiconductor disk laser. The larger surface area of the disk laser compared to the VCSEL laser allows more radioisotope to be accommodated, which increases the pump power and also increases the output power of the laser.

Thus, the proposed disk semiconductor laser pumped by radiation has better characteristics than existing analogues, first of all, a lower generation threshold, as well as complete autonomy from external power supplies.

Claims (1)

A radiation-pumped semiconductor disk laser is a VCSEL laser with an external mirror, where a semiconductor heterostructure is used as an active element, characterized in that it contains a quantum dot structure, and a Ni-63 radioactive β-source, which is a film, is used as a pump source. with a radionuclide, placed inside the body of a semiconductor disk laser, which ensures complete autonomy of the laser complex from external sources of electrical power.

Images