Passive film switch for mode-locked infrared lasers

Highly stable polymethine-dye-based polymer switches for passive mode locking in neodymium lasers

“…Such absorbers should be highly efficient and photostable, they should have short excitedstate relaxation times, large absorption cross sections a, a reasonable service life, and be easy to use [1,2]. The last requirement is fully satisfied by solid-state passive laser switches (PLSs), particularly those with polymer matrices which are coloured by organic dyes [3][4][5][6][7][8]. Replacement of liquid PLSs with solid switches increases the reproducibility of the temporal and energy parameters of the output radiation [5,7] and simplifies greatly laser design.…”

“…The last requirement is fully satisfied by solid-state passive laser switches (PLSs), particularly those with polymer matrices which are coloured by organic dyes [3][4][5][6][7][8]. Replacement of liquid PLSs with solid switches increases the reproducibility of the temporal and energy parameters of the output radiation [5,7] and simplifies greatly laser design. Passive switches [4,5] which are free films without facilities for mechanical displacement of the working zone are unsuitable for pulse-periodic lasers and have to be handled carefully because of their low resistance to abrasion.…”

“…Replacement of liquid PLSs with solid switches increases the reproducibility of the temporal and energy parameters of the output radiation [5,7] and simplifies greatly laser design. Passive switches [4,5] which are free films without facilities for mechanical displacement of the working zone are unsuitable for pulse-periodic lasers and have to be handled carefully because of their low resistance to abrasion. It is much preferable to adopt a triplex block configuration [3,6,7] in which a coloured polymer film is sandwiched between optical substrates that ensure the removal of heat, prevent penetration of atmospheric oxygen, and protect the polymer film from mechanical damage.…”

“…For example, the data on the photostability of a polymer film subjected to light pulses from a flashlamp given in Ref. [5] are insufficient because of the lack of information on the energy parameters of the incident radiation. We investigated the relative photostability of liquid (ethanol) solutions of dyes when they were irradiated with unresolved light from a DRK-120 ultrahigh-pressure mercury arc lamp and the radiation density in the sample zone was 7^35 mW cm" 2 .…”

“…Spectra of electronic absorption (extinction) £ of solutions of PD-4965 (/, 2) and PD-5596(5,4) in ethanol(1,3) and in a polyurethanematrix(2,4).…”