Ignacio Iparraguirre

Stimulated and upconverted emissions of Nd3+ in a transparent oxyfluoride glass-ceramic

Abstract The stimulated emission properties of Nd3+ ions in an oxyfluoride glass-ceramic have been studied. Ultraviolet and visible emissions generated by upconversion processes inside the laser cavity under lasing and non-lasing conditions have been also characterized. The expected losses produced by these processes have been estimated.

Spectroscopic and laser properties of Nd/sup 3+/ in BIGaZLuTMn fluoride glass

The optical properties of Nd/sup 3+/-doped fluoride BIGaZLuTMn glass have been investigated by using steady-state and time-resolved laser spectroscopy. Laser action has been obtained for the first time in this glass by flashlamp pumping. The influence of site-dependent effects on fluorescence lifetime and time-resolved stimulated emission has been proved. >

Broadband laser tunability of Nd 3+ ions in 0.8CaSiO 3 -0.2Ca 3 (PO 4 ) 2 eutectic glass

Site-selective spectroscopy and stimulated emission experiments performed in the (4)F(3/2)-->(4)I(11/2) laser transition of Nd(3+)-doped 0.8CaSiO(3-) 0.2Ca(3)(PO(4))(2) eutectic glass are presented. The spectral features of the excitation spectra and those of spontaneous and stimulated emissions reveal the existence of a very complex crystal field site distribution for Nd(3+) ions. As a consequence, the stimulated emission of Nd(3+) in this glass shows a tunability of about 10 nm as a function of excitation wavelength.

K5Nd(MoO4)4: a self-tunable laser crystal.

We report for the first time to our knowledge an experimental demonstration of wavelength self-tuning in a K5Nd(MoO4)4 broadband-emitting laser crystal (KNM), as well as a theoretical treatment of the system based on its birefringence properties. The self-frequency-tuning of the laser along the full spectral range of the KNM crystal was obtained by rotating a birefringent gain plate in its own plane. The gain plate was placed inside a resonator at Brewsters angle. The tuning characteristics of the spectral filter were obtained by use of the Jones vector formalism. The calculated wavelength-selective tuning precisely matches the experimental observations.

Diffusive random laser modes under a spatiotemporal scope

At present the prediction and characterization of the emission output of a diffusive random laser remains a challenge, despite the variety of investigated materials and theoretical interpretations given up to now. Here, a new mode selection method, based on spatial filtering and ultrafast detection, which allows to separate individual lasing modes and follow their temporal evolution is presented. In particular, the work explores the random laser behavior of a ground powder of an organic-inorganic hybrid compound based on Rhodamine B incorporated into a di-ureasil host. The experimental approach gives direct access to the mode structure and dynamics, shows clear modal relaxation oscillations, and illustrates the lasing modes stochastic behavior of this diffusive scattering system. The effect of the excitation energy on its modal density is also investigated. Finally, imaging measurements reveal the dominant role of diffusion over amplification processes in this kind of unconventional lasers.

Cr/sup 3+//spl rarr/Nd/sup 3+/ energy transfer and Nd/sup 3+/ laser action studies of La/sub 3/Ga/sub 5/SiO/sub 14/:Cr/sup 3+/,Nd/sup 3+/ co-doped crystal

Energy transfer between Cr/sup 3+/ and Nd/sup 3+/ ions has been investigated in the 4.2-300-K temperature range by using steady-state and site-selective time-resolved laser spectroscopy. Radiative and nonradiative energy transfer has been studied from the time-resolved emission spectra and the donor fluorescence decays. The transfer efficiency was calculated as a function of temperature by using the Cr/sup 3+/ lifetimes of the single doped and co-doped samples. Laser experiments were carried out in a diffusive cavity by pumping a co-doped rod 54 mm long and 5 mm in diameter with xenon flashlamps. The laser spectral emission shows a complex structure which varies as a function of pump energy. The temporal evolution of the laser spectrum is discussed in terms of a simple four-level spectral rate-equation laser model which takes into account the existence of two main broad Nd/sup 3+/ site distributions with a large spectral overlap.

Wavelength tuning of Titanium Sapphire Laser by its own crystal birefringence

We report for the first time to our knowledge an experimental demonstration of wavelength tuning in a broadband-emitting Ti: sapphire laser crystal based on its own birefringence properties. To investigate the tuning characteristics of the spectral filter, we have used Jones-Vector formalism. The calculated wavelength-selective tuning matches very precisely the experimental observations.

Laser action and infrared-to-visible upconversion processes of Nd3+ in yttrofluorite crystals

In this work, together with the laser dynamics and for the first time, the study of upconversion processes that produce violet and visible emissions in yttrofluorite mixed crystals with 15 wt% of YF3, and 1, 4, 8, and 16 wt% of NdF3 is presented. Site-selective excitation of Nd-doped yttrofluorite crystals by using spectrally narrow pump pulses have shown that it is possible to lase these materials in a single line at 1054 nm or at 1063 nm independently, or simultaneously in both lines depending on the Nd3+ concentration and the excitation wavelength. The upconversion measurements were conducted in such a way that the dynamics of the violet and visible fluorescence was performed under lasing and nonlasing conditions. The dynamics of the upconverted emission shows that both energy transfer upconversion and excited state absorption of the laser emission occur.

Upconversion processes and laser action in K5Nd(MoO4)4 stoichiometric crystal

In this work we report the upconversion processes that produce blue, green, orange, and red emission in K5Nd(MoO4)4 stiochiometric crystal together with the dynamics and spectral properties of the laser emission. It was found that upconversion energy transfer processes reduce the energy storage capacity through the reduction of the fluorescence lifetimes of the metastable 4F3/2 level. The experiments were conducted in such a way that the dynamics of the IR and visible fluorescence was performed under lasing and nonlasing conditions. The dynamics of the unconverted emission shows that both upconversion energy transfer and excited state absorption of the laser emission occur.

A performance study of Nd-based stoichiometric random lasers

This work presents a comparative study of the random lasing performance of several Nd-based stoichiometric compounds, including threshold and absolute slope efficiencies together with a discussion about the fundamental parameters which control the random laser operation in this kind of compounds.