Space-selective tailoring of porous glass matrix density via femtosecond laser pulses Текст научной статьи по специальности «Физика»

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Space-selective tailoring of porous glass matrix density via femtosecond laser pulses

Z. Lijing1, R Zakoldaev1, S. Maksim1, V. Veiko1

1ITMO University, Department of Laser Systems and Technologies, Sanct-Petersburg, Russian Federation

In the past decade, high silica porous glass (PG) has been successfully demonstrated as a functional platform for fabrication of fluidics devices, sensors, and for host of active centers such as Bi, Er, etc. [1,2]. In particular, gas analysis based on a PG has recommended the following ratio: one glass plate applies for one type of detected gas [3], i.e. one functional platform occupies the whole PG plate. Thus, the integration of several functional platforms at one PG plate remains a technological problem.

Our team develops ways and methods for density control of PG by utilization of ultrashort laser pulses providing local heating inside the material, leading to local density change classified by four types: pores collapse (so-called "densification"), rarefaction, voids appearance and channel formation [4]. The investigation of the morphological properties, material density especially for densification type, and its tailoring remains a present task. Local control of PG matrix density will open the way for integration of photonic elements (waveguides, splitters, and combiners) and fluidic structures (molecular barriers, solution separators) in single PG platform.

In this work, densified regions which work as waveguides inscribed by femtosecond laser pulses (1035 nm, 220 fs, 1 MHz) were adopted for investigation of refractive index change (An) based on a measured near field distribution of guiding mode. By correlating An with the change of PG matrix density, i.e. positive An means densification and negative An indicates rarefaction of glass matrix, we found a "core-cladding" structure of these waveguides in the cross-section, where a rarefaction region surrounds a densified region and they act as a core and cladding respectively.

References

[1] Sugioka, Koji, etc. Lab on a Chip 14, no. 18 (2014): 3447-3458.

[2] Iskhakova, Liudmila D., etc. Journal of Non-Crystalline Solids 503 (2019): 28-35.

[3] Maruo, Yasuko Yamada. Sensors and Actuators B: Chemical 126, no. 2 (2007): 485-491.

[4] V. P. Veiko, etc. Laser Phys. Lett. 13, 055901 (2016).