Applied Physics A

, Volume 84, Issue 3, pp 257–260

Influence of focusing depth on the microfabrication of waveguides inside silica glass by femtosecond laser direct writing

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DOI: 10.1007/s00339-006-3610-4

Cite this article as:
Liu, D., Li, Y., An, R. et al. Appl. Phys. A (2006) 84: 257. doi:10.1007/s00339-006-3610-4


We studied the influence of focusing depth on the index change threshold and damage threshold of silica glass irradiated by a focused 120 fs laser beam. Both thresholds increased with the focusing depth. The aspect ratio of the waveguide cross section can be selected by changing the focusing depth. A 5 mm long waveguide was written at the depth of 2100 μm, which was single mode at 632.8 nm and exhibited propagation loss of 0.56 dB/cm. The refractive index change was calculated to be ∼2.47×10-3. The influence of the focusing depth should be considered in multi-layer devices as shown in the fabrication of a 3×3 waveguide array.

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© Springer-Verlag 2006

Authors and Affiliations

  • D. Liu
    • 1
  • Y. Li
    • 1
  • R. An
    • 1
  • Y. Dou
    • 1
  • H. Yang
    • 1
  • Q. Gong
    • 1
  1. 1.State Key Laboratory for Mesoscopic Physics and Department of PhysicsPeking UniversityBeijingP.R. China