A multiwave CuBr and PbBr2 laser with a sectioned active volume
Introduction
Multicomponent lasers are of interest because they can be operated at several wavelengths simultaneously, which is required, e.g., for multifrequency atmospheric sounding, medium diagnostics, and research purposes. Metal- and metal salt vapor lasers operating at self-contained transitions possess similar mechanisms of inverse population generation and conditions of active medium excitation close with respect to parameters (the length and value of current and voltage pulses). One type of buffer gas and close optimal values of its pressure make it possible to form a common medium, while high gain coefficients allow operation at a shorter active zone as compared with the distance between the cavity mirrors. These properties provide for using several active media in one volume.
At the same time, different temperatures of active media are required to obtain optimal concentrations of individual components. Optimal pumping conditions should also be different. In addition, laser media can affect each other. Due to these reasons, even though lasing can be achieved simultaneously in different media in one volume, the power parameters of the lasing are not high. Hence, to optimize the operating mode relative to lasing power in the laser active volume, special zones are designed whose temperatures are different owing to variations of heat insulator properties; this allows the component composition of metal vapor lasers to be extended [1]. However, in the foregoing design of the active element, different requirements imposed on excitation pulses prevent using the capabilities of multicomponent lasers in full measure.
The development of a multiwave Sr and CuBr vapor laser was earlier reported in [2]. The IR radiation of an Sr laser was visualized by the CuBr laser radiation. In this case, the active element of the laser consisted of two sections with different active media. An additional electrode was inserted between the sections. The radiation power was distributed between the sections as 0.6 W (Sr) and 0.4 W (CuBr). The lasing occurred at 6.456, ∼ 3, and ∼ 1 μm of Sr lines, and at 0.51 and 0.57 μm of Cu lines. Thus, the multiwave lasing mode was realized due to the multicomponent active medium and IR-lasing was visualized, which provided control over the radiation path. This design of active element allows the active media with respect to the temperature regime and excitation parameters of each medium to be optimized.
In this work, we report the results of investigation into a two-section gas-discharge tube (GDT) where the sections were filled with CuBr and PbBr2.
Section snippets
Experimental setup
The experimental setup used in the experiments is shown in Fig. 1.
A special feature of the work is the use of a sectioned laser element with different active media in the sections. Correspondingly, GDT (2) is a discharge channel made of optically pure quartz of 20 mm in inner diameter and 1.5 mm in thickness with three electrodes equidistant from each other (450 mm): cathode (6), central electrode (7), and anode (8). The central electrode divides the discharge channel into two equal sections.
Experimental results and discussion
It is known that the use of small active volumes in self-contained metal vapor lasers provides the best energy pick-up. The point is that a high excitation pulse-rise rate is required for effective excitation of a laser medium, as well as a high Е/Р value when possible. First, an increase in volume results in an automatic increase in discharge circuit inductance decreasing the excitation pulse-rise rate, and, second, an increase in length decreases the Е/Р value, which decreases the laser
Conclusions
Our investigations show that the specific features of metal vapor lasers, i.e., high amplification, high efficiency of inverse population in small active volumes due to small inductance of the discharge circuit, make it possible to develop multicomponent lasers with a wide set of lasing lines using spatial and electric sectioning. In particular, the effective operation of a CuBr and PbBr2 vapor laser with simultaneous lasing at 722.9, 578.2, and 510.6 nm is possible. The average lasing power is
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