Transient light-induced refractive index change made by laser microfabrication in nitroaniline-doped PMMA film

Kazuhiko Yamasaki, Saulius Juodkazis, Mitsuru Watanabe, Shigeki Matsuo, Kenji Kamada, Koji Ohta, Hiroaki Misawa

Research output: Contribution to journalConference articlepeer-review

5 Citations (Scopus)


We report the observation of high light-induced change in refractive index (recognizable by observation in conventional microscope) in PMMA film doped with an optically non-linear dye 2-nitroaniline (NO2(C6H4)NH2 abbreviated as 2NA). The optically altered micrometer-sized regions were fabricated by single-shot irradiation of 120 fs laser pulses into doped PMMA film using high numerical aperture 1.3 and high magnification ×100 objective lens. The doping of films can be achieved in a wide range of 2NA concentrations (up to 40 wt%) without precipitation. This allows to control a storage time of an optically altered region up to one month by the adjusting the energy of the femtosecond (fs) recording pulse at 800 nm. Typical recording energy was 10-80 nj/pulse at the point of irradiation. Total recovery of transmission of the PMMA|2NA film was confirmed by optical transmission measurements in microscope. The light induced damage threshold (LIDT) (for permanent damage) was increased more than by 4 times (up to 40 nJ/pulse) when 2NA doping were ca. 13 wt%. While the LIDT for transient damage was decreased by 1.5-2 times. Total optical recovery was observed single exponential with decay time of ca. 0.5-1 min for moderate irradiation intensities (0.1×LIDT of permanent damage). The damage induced with at the higher intensities lasts up to month, but the recovery was not total (residual transmission changes were observable). The phenomenon can be applied for the optical memory, photonic crystal, and micro-mechanical applications. The underlying mechanism of the phenomenon is discussed in terms of anelastic α- and β-relaxation (polymer backbone and side chain relaxation, respectively).

Original languageEnglish
Pages (from-to)51-54
Number of pages4
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2000
Externally publishedYes
Event1st International Symposium on Laser Precision Microfabrication - Omiya, Jpn
Duration: 2000 Jun 142000 Jun 16

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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