Optimization of laser energy deposition for single-shot high aspect-ratio microstructuring of thick BK7 glass

We investigate the generation of high aspect ratio microstructures across 0.7 mm thick glass by means of single shot Bessel beam laser direct writing. We study the effect on the photoinscription of the cone angle, as well as of the energy and duration of the ultrashort laser pulse. The aim of the study is to optimize the parameters for the writing of a regular microstructure due to index modification along the whole sample thickness. By using a spectrally resolved single pulse transmission diagnostics at the output surface of the glass, we correlate the single shot material modification with observations of the absorption in different portions of the retrieved spectra, and with the absence or presence of spectral modulation. Numerical simulations of the evolution of the Bessel pulse intensity and of the energy deposition inside the sample help us interpret the experimental results that suggest to use picosecond pulses for an efficient and more regular energy deposition. Picosecond pulses take advantage of nonlinear plasma absorption and avoid temporal dynamics effects which can compromise the stationarity of the Bessel beam propagation.

[1]  Yasushi Shinohara,et al.  First-principles simulation of the optical response of bulk and thin-film α-quartz irradiated with an ultrashort intense laser pulse , 2013, 1312.5051.

[2]  R. Stoian,et al.  [INVITED] Ultrafast laser photoinscription of large-mode-area waveguiding structures in bulk dielectrics , 2016 .

[3]  T. Baumert,et al.  Control of ionization processes in high band gap materials via tailored femtosecond pulses. , 2007, Optics express.

[4]  Ottavia Jedrkiewicz,et al.  Experimental investigation of high aspect ratio tubular microstructuring of glass by means of picosecond Bessel vortices , 2015 .

[5]  Razvan Stoian,et al.  Flipping the sign of refractive index changes in ultrafast and temporally shaped laser-irradiated borosilicate crown optical glass at high repetition rates , 2008 .

[6]  A. Couairon,et al.  Practitioner’s guide to laser pulse propagation models and simulation , 2011 .

[7]  Craig B. Arnold,et al.  Bessel and annular beams for materials processing , 2012 .

[8]  D. Faccio,et al.  Nonlinear light-matter interaction with femtosecond high-angle Bessel beams , 2012 .

[9]  E. Yablonovitch,et al.  Avalanche Ionization and the Limiting Diameter of Filaments Induced by Light Pulses in Transparent Media , 1972 .

[10]  Peter G. Kazansky,et al.  ``Quill'' writing with ultrashort light pulses in transparent materials , 2007 .

[11]  Razvan Stoian,et al.  Single-shot high aspect ratio bulk nanostructuring of fused silica using chirp- controlled ultrafast laser Bessel beams , 2014 .

[12]  J. C. Losada,et al.  Underlying conservation and stability laws in nonlinear propagation of axicon-generated Bessel beams , 2015, 1508.05877.

[13]  Ottavia Jedrkiewicz,et al.  Laser micro- and nanostructuring using femtosecond Bessel beams , 2011 .

[14]  E. Mazur,et al.  Ultrafast laser processing of materials: a review , 2015 .

[15]  A. Piskarskas,et al.  Observation of conical waves in focusing, dispersive, and dissipative Kerr media. , 2007, Physical review letters.

[16]  A. Couairon,et al.  Plasma absorption evidence via chirped pulse spectral transmission measurements , 2015 .

[17]  Daniele Faccio,et al.  Filamentation in Kerr media from pulsed Bessel beams , 2008 .

[18]  Maxime Jacquot,et al.  High aspect ratio nanochannel machining using single shot femtosecond Bessel beams , 2010 .

[19]  Razvan Stoian,et al.  Role of free carriers excited by ultrafast Bessel beams for submicron structuring applications , 2014 .

[20]  Seongho Cho,et al.  Properties of optical breakdown in BK7 glass induced by an extended-cavity femtosecond laser oscillator. , 2009, Optics express.