*
ALT'23 The 30th International Conference on Advanced Laser Technologies
LS-P-1
Laser modification of optical properties of PbSe films by continuous
radiation at a wavelength of 405 nm
M. A. Dubkova, A. A. Patrikeeva, A. A. Olkhova, M. M. Sergeev
National Research University ITMO, St. Petersburg, 197101, Russia
maria. [email protected]
Chalcogenide PbSe films are widely used as a photosensitive element in gas analysis devices due to high absorption in the IR spectral range from 1 to 4 microns [1]. To increase the efficiency of detection of various toxic gases by these sensitive elements, the optical properties of PbSe films can be improved by laser exposure.
In this study, modification of the structure of PbSe films using continuous laser radiation at a wavelength of 405 nm is considered as an alternative to heat treatment in a furnace. Laser processing of the sample took place in the darkening mode and in the bleaching mode, which was observed when the film was scanned again in the darkening mode.
As a result of laser modification, the structure of the sample was changed, as well as the recrys-tallization of the material without the formation of an oxide crystal phase in the processing zone, in contrast to the processing in the furnace. This feature is an advantage, since the presence of oxide can contribute to the degradation of the film and reduce its service life. Laser treatment also led to a change in the reflection and transmission of the film in the IR region of the spectrum (Fig. 1) corresponding to the absorption peaks of toxic gases [2].
Thus, the use of laser irradiation makes it possible to carry out local modification of the structure and the predicted change in the optical characteristics of the films and can compete highly with heat treatment in the furnace.
-Untreated film
-Good heat treatment
Laser modification:
-Darkening
-Bleaching
4,5 5,0 5,5 Wavelength, ,um
4,5 5,0 5,5
Wavelength, nm
Fig. 1. Fourier spectra of (a) reflection (excluding the film substrate) and (b) transmission (taking into account the film substrate) obtained for samples subjected to various treatments: initial sample (blue curve), sample after heat treatment (red curve). Sample after laser modification in the darkening mode modified by continuous radiation (dark green curve), a sample after laser modification in the bleaching mode modified by continuous radiation (light green curve); Absorption spectra of various gases (CH4, CO2, CO, NO, NO2, NH3) [3].
[1] C. L. Tan and H. Mohseni, Emerging technologies for high performance infrared detectors, Nanophotonics, 7.(1), pp.169-197, (2018).
[2] M. Vainio and L. Halonen, Mid-infrared optical parametric oscillators and frequency combs for molecular spectroscopy, Physical Chemistry Chemical Physics, 18.(6), pp. 4266-4294, (2016).
[3] A. A. Olkhova et al., Comparison of CW NUV and Pulse NIR Laser Influence on PbSe Films Photosensitivity, Applied Sciences, 13.(4), pp.2396, (2023)
Acknowledgment: this research was funded by the Russian Science Foundation grant (project no. 23-29-10081), grant UMNIK.PHOTONICS.