book of abstracts - IM2NP

A B S T R A C T S TUESDAY, JUNE 29 N A N O S E A 2 0 1 0
emission with the required operating wavelengths (C-band, 1530 - 1560 nm). X-ray Interference Lithography
(XIL) has been chosen as the preferential technique to produce the gratings that provide the optical feedback.
2 – Abstract
In the last years optical gain from organic active media has been observed at different wavelengths lying in
the near-IR region (up to 1300 nm) [1-3] but still far from the wavelengths required for the optical
communications. P. Del Carro et al. have recently fabricated a distributed feedback (DFB) laser tunable in
the range of 890 - 930 nm [4]. Here we present an organic DFB laser exploiting the 4f – 4f transition at 1535
nm of the Er ion coordinated to the three Quinoline groups of the ErQ3 molecule. A film of amorphous ErQ3
is deposited by Vacuum Thermal Evaporation on a periodically modulated surface obtained by XIL.
According to the Bragg condition with the first order of emission (m=1) at 1535 nm, a 472 nm‐pitch has
been calculated for the DFB cavity and reproduced on the samples with nanometric precision. XIL represents
the obvious choice to obtain periodic structures, with its capacity to engrave (in few minutes) large areas of
photoresist (~ 1 mm2) with nanometer (100 nm) size ordered patterns without making use of masks. The XIL
tool is a low-cost apparatus made of a table-top coherent X-ray source and a simple Lloyd‟s setup where the
interference patterns are produced by reflection of one half of the laser beam that overlaps with the
undeflected half in correspondence of the sample surface [5]. The X-ray laser source is a prototype capillary
discharge plasma source developed at the University of L‟Aquila and emitting 1.5 ns long pulses of coherent
radiation at λ = 46.9 nm with 0.1 Hz maximum repetition rate, exploiting the single pass amplification of the
3p-3s transition in Ne-like Ar [6].
The effects of the grating surface modulation on the emission properties have been studied as a function of
the grating period (easily and cheaply tunable with the XIL technique) and of the organic layer thickness. A
morphological characterization has been performed by Atomic Force Microscopy on both the grating surface
and the active layer surface. Detailed X-Ray Photo-Emission Spectroscopy measures have been performed to
complete the characterization of the device.
3 – Conclusion
The largely diffused use of wide-band optical networks and the increasing request of improving their
performance are pushing toward the concept of an all-optical information processing. The fabrication of a
miniaturized organic laser for C-band applications is a step toward an all-optical scenario. The technological
impact of the novel device will depend on the possibility to adopt the on-chip optical interconnection
strategy diffusely: the low costs of constituent materials and fabrication techniques are the premise for a vast
diffusion of the ErQ3-based laser throughout the network.
[1] M. Casalboni, F. De Matteis, V. Merlo, P. Prosposito, R. Russo and S. Schutzmann, Appl. Phys. Lett. 83, 416 (2003).
[2] K. Yamashita, T. Kuro, K. Oe and H. Yanagi, Appl. Phys. Lett. 88, 241110 (2006).
[3] J. Thompson, M. Anni, S. Lattante, D. Pisignano, R. I. R. Blyth, G. Gigli and R. Cingolani, Synth. Met. 143, 305 (2004).
[4] P. Del Carro, A. Camposeo, R. Stabile, E. Mele, L. Persano, R. Cingolani, and D. Pisignano, Appl. Phys. Lett. 89, 201105 (2006).
[5] P. Zuppella, D. Luciani, P. Tucceri, P. De Marco, A. Gaudieri, J. Kaiser, L. Ottaviano, S. Santucci and A. Reale, Nanotechnology, 20 (2009),
115303.
[6] A. Ritucci, G. Tomassetti, A. Reale, F. Flora and L. Mezi, Phys. Rev. A 70, 023818 (2004).
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