37,380 research outputs found
Polarized micro-Raman studies of femtosecond laser written stress-induced optical waveguides in diamond
Understanding the physical mechanisms of the refractive index modulation
induced by femtosecond laser writing is crucial for tailoring the properties of
the resulting optical waveguides. In this work we apply polarized Raman
spectroscopy to study the origin of stress-induced waveguides in diamond,
produced by femtosecond laser writing. The change in the refractive index
induced by the femtosecond laser in the crystal is derived from the measured
stress in the waveguides. The results help to explain the waveguide
polarization sensitive guiding mechanism, as well as providing a technique for
their optimization.Comment: 5 pages, 4 figure
Femtosecond-laser-irradiation-induced structural organization and crystallinity of Bi2WO6
Controlling the structural organization and crystallinity of functional oxides is key to enhancing
their performance in technological applications. In this work, we report a strong enhancement of
the structural organization and crystallinity of Bi2WO6 samples synthetized by a microwave-assisted
hydrothermal method after exposing them to femtosecond laser irradiation. X-ray difraction, UVvis and Raman spectroscopies, photoluminescence emissions, energy dispersive spectroscopy, feld
emission scanning electron microscopy, and transmission electron microscopy were employed to
characterize the as-synthetized samples. To complement and rationalize the experimental results, frstprinciples calculations were employed to study the efects of femtosecond laser irradiation. Structural
and electronic efects induced by femtosecond laser irradiation enhance the long-range crystallinity
while decreasing the free carrier density, as it takes place in the amorphous and liquid states. These
efects can be considered a clear cut case of surface-enhanced Raman scattering
On-chip electro-optic tuning of a lithium niobate microresonator with integrated in-plane microelectrodes
We demonstrate electro-optic tuning of an on-chip lithium niobate
microresonator with integrated in-plane microelectrodes. First two metallic
microelectrodes on the substrate were formed via femtosecond laser process.
Then a high-Q lithium niobate microresonator located between the
microelectrodes was fabricated by femtosecond laser direct writing accompanied
by focused ion beam milling. Due to the efficient structure designing, high
electro-optical tuning coefficient of 3.41 pm/V was observed.Comment: 6 pages, 3 figure
Thermally-Reconfigurable Quantum Photonic Circuits at Telecom Wavelength by Femtosecond Laser Micromachining
The importance of integrated quantum photonics in the telecom band resides on
the possibility of interfacing with the optical network infrastructure
developed for classical communications. In this framework, femtosecond laser
written integrated photonic circuits, already assessed for quantum information
experiments in the 800 nm wavelength range, have great potentials. In fact
these circuits, written in glass, can be perfectly mode-matched at telecom
wavelength to the in/out coupling fibers, which is a key requirement for a
low-loss processing node in future quantum optical networks. In addition, for
several applications quantum photonic devices will also need to be dynamically
reconfigurable. Here we experimentally demonstrate the high performance of
femtosecond laser written photonic circuits for quantum experiments in the
telecom band and we show the use of thermal shifters, also fabricated by the
same femtosecond laser, to accurately tune them. State-of-the-art manipulation
of single and two-photon states is demonstrated, with fringe visibilities
greater than 95%. This opens the way to the realization of reconfigurable
quantum photonic circuits on this technological platform
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