323,053 research outputs found
Amplitude noise and timing jitter of pulses generated by supercontinuum spectrum-slicing for data-regeneration and TDM/WDM applications
No full text5-GHz repetition-rate dual-wavelength pulse-train generation from an intracavity frequency-modulated Er-Yb:glass laser
No full text(INVITED) Flexible photonics for biomedical applications: A review
No full textFlexible photonics is a powerful tool that has emerged in last few decades to solve footprint and shape related limitations in photonic devices. Indeed, flexible photonic devices offer several key features: ability to adjust to complex shape surfaces, small footprint, high resilience to mechanical damage, immunity to electromagnetic interference. Thanks to these characteristics, these devices are very attractive for applications in the biomedical field. For instance, the flexibility allows optimal adhesion to the skin, or the reduced size facilitates the realization of wearable devices. In this paper, we will first present the characteristic of flexible photonic devices and discuss about the so far impact of flexible photonics in the biomedical field. Then, we will analyze the currently existing devices and the main used components, with a focus on the applications
High-repetition-rate picosecond pulse generation at 1.5 μm by intracavity laser frequency modulation
No full textWe propose and experimentally demonstrate generation of transform-limited pulse trains at a 2.5-GHz repetition rate from a frequency-modulated erbium - ytterbium bulk glass laser by using an intracavity lithium niobate phase modulator and an external fiber Bragg grating filter. Light pulses with durations tunable from 40 to 80 ps and 0.2-mW fiber-coupled average power at 1535 nm have been obtained. © 1997 Optical Society of America
Design and fabrication of fiber optic sensors and systems for aerospace applications
No full textThe rapid evolution of fiber optic technology has revolutionized the field of communication
and sensing, enabling unprecedented levels of accuracy, miniaturization,
and scalability. This thesis describes the results obtained during my Ph.D.
activity and concerning the development of fiber optic sensors, optical fiber
components, and light sources tailored to advance the field of aerospace structure
monitoring. The work has required the exploration of the research forefront in
this field.
The first part of the thesis focuses on the design, fabrication, and characterization
of non-conventional fiber optic sensors. These sensors leverage Bragg
gratings to detect several physical parameters, including temperature, strain, and
bending, matching the stringent requirement of structural health monitoring of
Carbon Fiber Reinforced Polymers (CFRP). The findings have been obtained in
collaboration with the University of Southampton (Optoelectronic Research
Centre - ORC, UK) trying to give a contribution to the ongoing evolution of
aerospace sensor technologies.
Bragg gratings are wavelength-selective structures also employed for multiplexing
optical signals or for the construction of laser cavities. By considering
these aspects and the growing interest in Medium-Infrared (Mid-IR) spectral
range, the second part of the thesis delves into the design, fabrication, and characterization
of Mid-IR optical fiber components, based on soft glasses, operating
between 0.5 μm and 12 μm. Optical fiber combiners/couplers are essential elements
in communication and sensing systems that enable the splitting (or combining)
of optical signals into (from) a single optical fiber preserving beam quality.
The development of a custom manufacturing procedure for fluoride and chalcogenide
glasses, in collaboration with the company Le Verre Fluoré (Bruz,
France) made it possible, for the first time, to address the results described in the
doctoral thesis.
Moreover, Bragg gratings in combination with these optical fiber components
allow the development of all-in-fiber Mid-IR amplifiers, lasers, and wavelength
division multiplexing (WDM) systems. In particular, optical fiber lasers, operating in the Mid-IR spectral range, can be employed for material inspection
purposes to assess the integrity and quality of composite materials via Non-Destructive
Testing (NDT) techniques. Therefore, the design and optimization of
Mid-IR continuous wave (CW) lasers, are reported in the last part of the Ph.D.
research work.
Part of the obtained results have been published in International Journals and
in the Proceedings of National and International Conferences, as listed at the end
of the thesis
Single-frequency glass waveguide lasers
No full textWe report results on a single-end pumped waveguide laser for sensing applications Output power in excess of 20 mW with 17% slope efficiency in robust single-frequency operation at 1533.5 nm is demonstrated. The overall laser cavity laser was 60-mm long but the active medium, an Er:Yb-doped phosphate glass, was only 9-mm long. The waveguide was fabricated by two-step Ag-Na ion-exchange technique. The overall cavity length including butt-coupled fiber- Bragg-grating mirrors was <60 mm. We also reports on recent work to reach 100-mW single-frequency output power. To extend the operation wavelength to 2-micron wavelength region we also developed new tellurite glasses. Preliminary results on glass investigation are also reported
Absolute frequency stabilization of two diode-pumped Er-Yb:glass lasers to the acetylene P(15) line at 1534 nm
No full textTwo identical diode-pumped bulk Er-Yb:glass lasers, operating at 1534-nm wavelength, have been independently locked to the P(15) rovibrational line of the acetylene molecule by the FM sideband technique. Measurements of the beat note between the two lasers show a long-term frequency stability of 170 kHz over a 1-h period and a short-term laser linewidth below 50 kHz over 1 ms. The Allan standard deviation of the beat frequency was measured yielding values below 10-10 for integration times between 10 ms and 1 s, reaching the 4×10-11 level at 0.1 s. © 1998 American Institute of Physics
Novel approach towards cross-relaxation energy transfer calculation applied on highly thulium doped tellurite glasses
No full textIn this paper we calculated, for the first time to the best of our knowledge, the cross relaxation parameter of Tm3+ ions in tellurite glasses over a wide range of concentrations: from 0.36 mol% up to 10 mol%. A new measurement approach based on emission spectra monitoring is proposed. This method is very simple and allows to measure even very highly doped samples. The obtained values of cross-relaxation parameter show a linear dependence with respect to dopant concentration over the full investigated interval, suggesting a dipole-dipole interaction process. The measured slope is 1.81x10^−17 cm^3 s^−1 mol%^−
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