Fluorescence image of possible paths for entangled photons in laser induced waveguides in silica
Within the past decade, the use of ultrashort laser pulses has found widespread attention for precise microstructuring. Particularly, the possibility to realize localized modifications within the bulk of transparent materials has recently attracted increasing interest. When intense ultrashort pulses are tightly focused into the transparent bulk material, the intensity in the focal volume can become high enough to initiate absorption through nonlinear field ionization. This results in the creation of an electron-ion plasma, leading to permanent structural changes inside the sample without affecting the surface. Depending on the processing parameters, either refractive index changes (isotropic or birefringent) or microvoids can be generated in the focus [MRS Bulletin 31, 620 - 625 (2006)External link].
Schematic illustration of key steps in ultrashort-pulse induced structural modifications inside transparent materials.
Illustration: Univ. Jena, IAPThese defined modifications are exploited for a variety of different applications:
- Inscription of Waveguides into Glasses and Crystals
- Discrete Optics in Photonic Lattices
- Integrated Photonic Quantum Computing
- Nanogratings
- Fiber Bragg Gratings / Volume Bragg Gratings
- Ultrashort Pulse Laser Welding
- Medical Applications
