Evaluation of the Optical and Electrical Properties of Oxy-chalcogenide GlassesK. Richardson, Clemson University,

S.W. Martin, Iowa State University, H. Jain, Lehigh UniversityDMR-0312081

The preparation of candidate oxysulfide materials for optical applications (waveguides) will result in glasses that combine the superb chemical stability of oxides and the attractive linear and non-linear optical properties of sulfide materials. The figure in right demonstrates the successful production of amorphous oxysulfide materials through the sulfination of a range of different starting oxide materials. The composition space of our study has been also broadened to multicomponent Ge,Ga,Sb,S,Se materials. We have shown that the non-linear refractive index, n2, of these new glasses increases with the substitution of Ge for Ga in the glass host system Ge – Sb - S. This n2 variation may be related to the total number of electronic lone pairs and to the position of the absorption band gap.

.

200 400 600 800 1000 1200 1400

0.5 GeO2 - 0.2 Sb

2O

3 - 0.30 B

2O

3

0.80 GeO2 - 0.2 Sb

2O

3

Inte

nsity

(A. U

.)

Wavenumber (cm-1)

Before sulfination After sulfination

Raman spectra of germanium antimony based glasses

(exc = 632 nm)

0 50 100 150 200 25050

100

150

200

250

300

350

Ge23

Sb7S

70

Ge18

Ga5Sb

7S

70

Photo

expan

sion (

nm

)

Dose (MJ/cm3)

The figure in left shows that the Ga-based glass is also photosensitive to laser irradiation. This glass exhibits a photo-expansion of the surface after laser irradiation. We have shown that the incorporation of Gallium in the germanate network increases the photosensitivity of the glass due to a redshift of bandgap but decreases the photoexpansion compared to that of Ga-free glass as seen in the below left figure. This may be understood by the presence of isolated GaS4 units in the germanate glass network which restrict structure variation under laser exposure. The evidence for photosensitivity of the sulfo-selenide and oxysulfide bulks/films has been demonstrated and shows promise for use in photonics devices, which deserves further study

Evaluation of the Optical and Electrical Properties of Oxy-chalcogenide GlassesK. Richardson, Clemson University,

S.W. Martin, Iowa State University, H. Jain, Lehigh UniversityDMR-0312081

Broader Impact-EducationThe broader impact of the proposed program is the global understanding, cultural and educational experiences realized by US-France team participants assembled to carry out this effort. The current NSF-EU program truly allows full integration of research and educational activities between researchers in both countries. The assemblage of glass science, chemistry and optical science researchers, brings to the effort a proven track record of educational outreach and mentoring. This effort continues to serve as a producer of high quality graduates who have shown capabilities and expertise across interdisciplinary boundaries. We continue to use 'during semester' research opportunities to seed new efforts that overlap into our summer REU programs (#EEC- 0244109). Shown (below right) is Julie Boudies, one of the 2006 INTL REU students, from the University of Bordeaux I presenting her summer research at the Poster presentation organized at CREOL (UCF/FL) in July 2006. This supports continuity in our program and also grooms undergraduates (US and Europeans) for graduate programs within and subsequent to our program. Shown (below left) is Jonathan Massera with Prof. K. Richardson. Jonathan was an 2005 INTL REU student from Polythech’Montpellier and worked at Clemson University on processing and IR femtosecond laser irradiation of novel sulfo-selenide glasses.

Jonathan is now a PhD student at Clemson under Prof. K. Richardson’s supervision. Our efforts from this funded effort are regularly exhibited at national and international conferences as oral or poster presentations. Additionally, students are routinely included as co-authors on peer-reviewed, refereed publications that result from their (INTL REU) experience.