High 90% efficiency Bragg gratings formed in fused silica by femtosecond Gauss-Bessel laser beams

Abstract

Direct laser write of volume Bragg gratings with diffraction efficiency (absolute) ∼90% is demonstrated using Gauss-Bessel laser beams in fused silica glass. Axial multiplexing of ∼ 90 µm long segments of modified optical material was demonstrated and thick Bragg gratings of aspect ratio depth/period ≈234 were achieved with period d = 1.5 µm. Typical fabrication scanning speeds were up to 50 mm/s for gratings with cross sections up to five millimeters made within 1 h time. Potential applications of high efficiency Bragg gratings in a low nonlinearity medium such as silica are discussed.

Femtosecond laser induced phenomena in transparent solid materials: Fundamentals and applications

“…These FBGs have been used as optical waveguides, waveguide retarders, polarization beam splitters, optical edge filters, temperature-compensated fiber-optic 3D shape sensor, etc. [229,321,323,[396][397][398][399][400]. Fig.…”

[INVITED] Ultrafast laser micro-processing of transparent material

“…This does not allow full exploitation of the three-dimensional capabilities of ultrafast laser micromachining. To overcome the limitations, an application of non-diffractive Bessel beams for laser material processing has been attempted [105][106][107][108][109][110][111][112][113][114]. The intensity maximum is strongly localized over a distance that exceeds the Rayleigh range of Gaussian beams by orders of magnitudes.…”

“…In glass, modifications or damage tracks are found to be over longer distances [106]. The applications include the surface ablation [107,108], channel formation [109,110], writing waveguides [111] and gratings [112] within bulk glasses, and cutting of glass [113]. …”

Femtosecond fiber laser welding of PMMA

“…Femtosecond laser processing of transparent materials, such as glasses, polymers, and crystals [1], has become a microfabrication technique of growing interest in several fields, particularly for the production of photonic and bio-medical devices since it allows direct fabrication of waveguides [2][3][4], gratings [5][6][7] and microfluidic channels [8][9][10][11][12][13].Based on this technology, several studies have demonstrated the ability of focused femtosecond laser pulses to weld similar [14,15] and dissimilar glasses [16][17][18] without the insertion of any intermediate light-absorbing layer. This innovative laser joining technique promises an easy and versatile integration of miniaturized devices.…”