RU2029424C1 - Method of cleaning active medium of liquid laser - Google Patents

Abstract

FIELD: quantum electronics. SUBSTANCE: active medium of liquid laser based on coumarin dye is pumped after radiation through layer of granulated sorbent saturated in advance with starting active medium till balance is established. Either zirconium oxide contacting titanium oxide or solid solutions of zirconium oxide with one of oxides of metals chosen from group of aluminium, yttrium rare Earth elements, calcium or magnesium is used as sorbent. EFFECT: enhanced cleaning efficiency. 2 tbl

Description

 The invention relates to quantum electronics, in particular to reusable dye lasers.

At present, liquid tunable lasers based on solutions of organic compounds are already used in various fields of science and technology. However, their application would be even wider if their service life (while maintaining high conversion efficiency) was higher. The most active photostable media of the blue-green spectrum, for example, provide a service life when the conversion efficiency drops by 2 times 300 J / cm ³ (energy pumped into 1 cm ^{3 of the} solution). Multicomponent mixtures based on ethanol coumarin 102 solutions can increase the resource to 1 kJ / cm ³ . However, with the advent of high-energy (pulse energy> 1 J) frequency (repetition frequency up to 1 kHz) pump lasers, in particular, xenon chloride, such an active medium resource is clearly not enough to create high-power laser systems. It is necessary to increase it by at least an order of magnitude (up to 10-50 kJ / cm ³ ).

 It is known to use both mechanical filters in a pumping system for liquid lasers designed to clean a dye solution of particulates that appear during operation due to wear of metal parts of a pump, etc., and special filters capable of cleaning the active medium from the resulting photoproducts [1].

 The closest in technical essence and the achieved technical result is the use of a liquid laser of aluminum oxide for cleaning the medium [2]. The disadvantage of this sorbent is its low efficiency of cleaning the active medium from photolysis products, the accumulation of which reduces the life of the liquid laser. In addition, during the operation of the laser due to photodecay, a decrease in the concentration of the active substance occurs, this is accompanied by a decrease in the gain, and, consequently, the generation efficiency. The use of aluminum oxide does not allow to stabilize the concentration of the active substance during the operation of the laser.

 The aim of the invention is to increase the service life of the active medium due to its regeneration and purification.

 The goal is achieved in that the active medium after irradiation is passed through a sorbent previously saturated with a solution of the initial active medium until equilibrium is established, and either zirconium oxide containing titanium oxide or solid solutions of zirconium oxide with one of the metal oxides selected from the group are used as the sorbent : aluminum, yttrium, rare earths, calcium, magnesium.

 As a result, the photoproducts formed during the training of the active medium are absorbed by the sorbent and the concentration of active molecules is restored, since the sorbent was previously saturated until equilibrium was established and it supports it. This leads to an increase in the life of the laser.

 The invention is illustrated by the following examples.

PRI me R s 1-3. The coumarin 102 dye alcohol solution with a concentration of C = (1.6-8) x10 ^-3 mol / L was irradiated with an xenon chloride excimer laser with an average pump power W _n = 10 MW / cm ² .

 The generation efficiency and the optical density of the solution were measured at the generation wavelength (λ = 477 nm).

An initial coumarin 102 solution was passed through a column with a sorbent pre-washed with alcohol until the coumarin concentrations at the column inlet and outlet levels were equalized (sorbent saturation stage). The diameter of the column is 10 mm, the load volume of the sorbent is 2 cm ³ . Then, an irradiated dye solution was passed through a column with a saturated dye at a rate of 60 ml / min 10 times. The characteristics of the initial, irradiated, and regenerated solutions are given in Table 1.

From the data in Table 1 it follows that when the working solution is irradiated due to the appearance of photolysis photoproducts, there is an increase in absorption at the generation wavelength (λ = 477 nm) and, as a result, the generation efficiency is halved. Subsequent transmission of the irradiated solution through a column with a sorbent leads to a decrease in the concentration of photolysis products (decrease in D ₄₇₇ ) and an increase in the generation efficiency almost to the initial value.

 A test of sorbents in the pumping system was carried out.

PRI me R s 8-12. A liquid column with a sorbent Z ₂ O ₂ containing various amounts of dye was included in the system for pumping a liquid laser with a volume of V = 20 cm ³ (ethanolic coumarin solution 102, C = 10 ^-3 mol / L). For comparison, a similar experiment was performed without a column with a sorbent. The data obtained are given in table.2.

 Irradiation parameters and pumping conditions are described in the previous example.

It was shown that in an active medium without a sorbent (Example 4), in two hours of the experiment, the generation efficiency decreased from 12 to 8.1%. The laser resource (time to reduce efficiency by half) was 3 h. In addition, an increase in absorption at λ = 477 nm to 0.036 and a decrease in optical density at the maximum of the absorption band of coumarin 102 (λ = 390 nm) from 1.24 to 1 were recorded. 0
If a sorbent that is not saturated with dye is loaded into the column, the laser life is reduced due to the absorption of the dye by the sorbent, although sorption of photoproducts takes place (Example 5). When using a sorbent saturated with a dye, the laser life increases linearly with increasing dye concentration (examples 6-8). The upper limit on the dye concentration is determined by the sorbent capacity and the dependence of the initial generation efficiency on concentration. At a concentration of 1.5 mg / g, the initial generation efficiency decreased by 20% compared to the optimal one, although at the same time the laser resource increased (Example 8).

When the dye content in the sorbent is 0.1-1 mg / g, a slower decrease in the concentration of the active component, a decrease in the concentration of photoproducts, and an increase in the resource of the active medium occur. So, at a dye concentration of 1 mg / g (Example 7) for 6 hours 30 minutes In the experiment, the generation efficiency decreased from 12 to 10.6%, the optical density at λ = 390 nm decreased to 1.12, D ₄₇₇ increased to 0.023.

 The environmental resource increased 10 times and amounted to 31 hours.

 Thus, the proposed cleaning method can significantly increase the resource of the active medium and can be used in all industrial liquid lasers.

Claims (1)

 METHOD FOR CLEANING THE ACTIVE MEDIUM OF A LIQUID LASER based on coumarin dyes by pumping through a layer of granular sorbent, characterized in that the sorbent is pre-saturated with the original active medium until equilibrium is established, while either zirconium oxide containing titanium oxide or solid solutions of zirconium oxide are used as the sorbent with one of the metal oxides selected from the group: aluminum, yttrium, rare earth elements, calcium, magnesium.

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