Direct writing in transparent materials using ultra short laser pulses: towards functionalization by controlling the induced phase shift Текст научной статьи по специальности «Медицинские технологии»

LP-O-6

Direct writing in transparent materials using ultra short laser pulses: towards functionalization by controlling the induced phase shift

B. Ancelot1, L. Gemini1, M. Faucon1, R Kling1 1ALPhANOV, Laser Processing, Talence, France

In the past years, the process of direct writing in transparent materials by femtosecond laser pulses has been thoroughly studied [1,2] and greatly developed thanks to its wide range of application fields such as optical waveguides generation [2-4], to mention only a few. Indeed, the use of ultrashort laser pulses combined to a tight laser beam focusing allows the generation of a permanent and local index change in the area of the focal point within the bulk of transparent materials [5]. However, the possibility to exploit this local refractive index change into functionalized components still faces substantial challenges since the induced laser phase shift must be controlled precisely.

The purpose of this work is to quantitatively evaluate the influence of laser parameters on the induced phase shift and its homogeneity within the bulk of polymers and fused silica for different laser patterns: 0D (single laser shot), 1D (single laser line) , 2D (multiple laser lines) and 3D (multiple laser lines at different z positions). An example of a single laser line phase shift measurement is illustrated on the figure 1.

\ \ \ \ / / / , Acp = -2,7

x(Mtn)

Fig. 1. Example of a single laser line phase shift measurement.

Influence of the pulse energy (from 0.1 pJ to 2 pJ), pulse to pulse overlap, focusing conditions and laser trajectory on the induced refractive index change is firstly investigated and a prototype for high-resolution fluorescence imaging application is finally realized in silica glass.

The wavelength and pulse duration of the laser employed in the study are 1030 nm and 350 fs, respectively. The wavelength is converted to 515 nm for the trials within polymers bulk. Phase shift characterization is carried by a quantitative phase imaging camera.

References

[1] V.P. Zhukov, N.M. Bulgakova and M.P. Fedoruk, J. Opt. Technol., Vol 84, 439-446 (2017).

[2] R. R. Gattass and E. Mazur, Nature Photonics, Vol 2, 219-225 (2008).

[3] K. Itoh, W. Watanabe, S. Nolte and C.B. Schaffer, MRS Bulletin, Vol.31, 620-625 (2006).

[4] W.M. Patzold, A. Demircan and U. Morgner, Optics Express, Vol 25, 263-270 (2017).

[5] S.S. Mao, F. Quere, S. Guizard, X. Mao, R.E. Russo, G. Petite and P. Martin, Applied Physics A, Vol. 79, 1695-1709(2004).