1,721,063 research outputs found
Widely tunable single-frequency erbium-ytterbium phosphate glass laser
No full textA tunable, single-frequency, diode-pumped miniature Er:Yb:glass laser of high power is described. The laser exhibits two intervals of continuous tuning, from 1549 to 1563 nm (Δλ=14 nm) and from 1531 to 1540 nm (Δλ=9 nm), respectively. For an input pump power of 140 mW, a single frequency output power of 20 mW at 1563 nm has been obtained. The tuning characteristics are found to be strictly related to the gain-loss balance of the laser cavity. © 1996 American Institute of Physics
(INVITED) Flexible photonics for biomedical applications: A review
Full text linkFlexible 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
Realizzazione e caratterizzazione di vetri drogati con terre rare per la fabbricazione di laser in fibra ottica
No full text2.1-μm lasers frequency stabilized against CO2 lines: Comparison between fringe-side and frequency-modulation locking methods
No full textA comparison between the use of the fringe-side and the frequency-modulation methods to frequency stabilize diode-pumped Tm-Ho:YAG lasers against linear absorption lines of CO2 near 2.1 μm is reported. Frequency stability was evaluated by monitoring of the beat signal between two independently stabilized Tm-Ho:YAG systems. Frequency instability levels of ∼20 and ∼400 kHz for 1-s integration time were achieved by the frequency-modulation and fringe-side methods, respectively. © 2003 Optical Society of America
Effective photodarkening suppression in Yb-doped fiber lasers by visible light injection
Full text linkAl-silicate fibers have excellent manufacturing quality. Unfortunately, high-Yb doping concentration may be limited by severe losses induced by photodarkening phenomenon. In this paper we demonstrate for the first time that Al-silicate Yb-doped fibers with highinversion and doping concentration above 1 wt% can be successfully used by implementing a simple optical bleaching scheme. A co-injection into the active fiber of a few mW of light at around 550 nm wavelength successfully eliminates almost all photodarkening induced losses. We demonstrate operation at above 90% of the pristine output power level in several lasers with up to 30% Yb ions in the excited state. These results may allow to use Yb-doped Al-silicate fibers with doping level increased by one order of magnitude. Finally, we provide a comprehensive picture of main parameters affecting photobleaching performance and, to the best of our knowledge, we report the first quantitative measurement of the Ytterbium excited state absorption cross-section in the visible range. © 2014 Optical Society of America
Theoretical and experimental analysis of intensity noise in a codoped erbium-ytterbium glass laser
No full textA comprehensive analysis of the mechanisms inducing intensity noise in a single-frequency, diode-pumped erbium-ytterbium glass laser is presented. Owing to the energy transfer between the codopant and the active material, the Er: Yb laser shows a markedly reduced sensitivity to pump power fluctuations, and hence its intensity noise spectrum is mainly determined by the fluctuations in the cavity losses. The experimental measurements confirm the results of the theoretical analysis. © Springer-Verlag 1998
Intensity noise reduction in a single-frequency ytterbium-codoped erbium laser
No full textWe report on intensity noise suppression in a diode-pumped, single-frequency erbium bulk-glass laser codoped with ytterbium. Using an optoelectronic feedback circuit, we acheived a 30-dB reduction of the relaxation oscillation peak, at 160-kHz frequency, to a relative intensity noise of -114 dB/Hz. A useful output power of 15 mW at 1533-nm wavelength was obtained. © 1996 Optical Society of America
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
Experimental analysis and theoretical modeling of a diode-pumped Er:Yb:glass microchip laser
No full textA comprehensive study of a diode-pumped Er:Yb:glass microchip laser, operating at 1530-nm wavelength, is presented. The operating conditions wherein a linearly polarized, single longitudinal and transverse mode operation is achieved are indicated. An optimum pump spot size that minimizes the threshold pump power and maximizes the slope efficiency is experimentally found and theoretically justified by a space-dependent rate-equation model. © 1995, Optical Society of America
Optoelectronic feedback loop for relaxation oscillation intensity noise suppression in Tm-Ho:YAG laser
No full textAn optoelectronic feedback loop that can be used to effectively reduce the intensity noise of a 2.1 μm Tm-Ho:YAG laser has been designed. The feedback circuit is based on a variable-gain biquadratic bandpass filter with adjustable central frequency and quality factor, providing a high loop gain around the relaxation oscillation frequency of the laser and a closed-loop phase margin larger than 50°. The relaxation oscillation peak in the intensity noise spectrum was completely suppressed in closed-loop operation and a noise reduction of up to 24 dB was obtained
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