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ion Pulse shaping resolves a key challenge of laser fabrication of

active single crystal architecture in glass Himanshu Jain, Lehigh University, DMR 0906763

Femtosecond laser is a unique tool for fabricating 3D single crystal architecture in a glass, but the process has been marred by the fact that the local temperature profile, hence the shape of the crystal varies with the depth in glass. Now the researchers at Lehigh University together with collaborators at Kyoto University have made significant progress in overcoming this challenge, as shown in figures. They shaped laser pulses to account for aberration introduced as the laser beam traversed deep into glass. Such pulse shaping is an important first step for producing consistent crystal growth conditions for 3D micro-optics.

Fig. 2: Inverse pole figure (IPF) electron diffraction maps show a single crystal orientation for each line. The secondary electron images (SEI) reveal a 'fine structure‘, which is currently under investigation.

Fig. 2Fig. 1

Fig. 1: Aberration-corrected growth increased the uniformity of individual crystal lines, but variation was seen in the shape of cross sections between different lines (colors show thickness and orientation variation).

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ion Probing the state of laser fabricated single crystal architecture in glass

Himanshu Jain, Lehigh University, DMR 0906763

Laser heating of glass offers high spatial selectivity, which can be exploited to create ferroelectric single-crystal architecture within glass. However, in order to become viable for active functionality, the characteristics of the crystal need to be better understood. Scanning confocal Raman and fluorescence spectroscopy, and combined excitation emission spectroscopy (CEES) measurements have given a most detailed insight about the state of an erbium doped LaBGeO5 crystal sample within the glass of same composition – see Figures 1 and 2. These results also provide guidance for optimizing the fabrication process.

Figure 1: 2D maps of the intensity of the 802cm-1 Raman peak (top) and erbium fluorescence (bottom) show significant disparity with respect to spatial distribution within the glass. Also there is an enhancement of the erbium fluorescence emission within the crystal, which exhibits remarkable asymmetry.Fig. 2. CEES maps of furnace crystallized (left) and laser

crystallized (right) Er.002La.998BGeO5 show differing strain environments.