Abstract
This work presents an overview of near infrared random lasing emitters based on a variety of neodymium (Nd3+)-doped crystal powders with different Nd3+ concentrations and different grain sizes. The pump-configuration used allows for an absolute measurement of both pumping and emitted energies. The results provide an absolute measure of the random laser efficiency and prove a relation of direct proportionality between the absorbance of the material and the laser slope efficiency. Likewise, they suggest a relationship close to an inverse proportionality between the absorbance and the threshold energy per unit area. The temporal behavior of the random laser emission shows noteworthy differences between local and spatially integrated registers.
Highlights
Scattering materials have attracted attention as laser sources due to potential applications such as high definition speckle-free phosphors, holographic laser displays, optical or chemical sensors for medical diagnosis, nanoscale lithography, miniature spectroscopy, etc [1,2,3].Conventional lasers are built on accurate reflecting cavities so they have a well defined direction, very high coherence and mode stability, etc
The results provide an absolute measure of the random laser efficiency and prove a relation of direct proportionality between the absorbance of the material and the laser slope efficiency
This result says that almost all pumping photons absorbed above the threshold are re-emitted as stimulated emission, which means that other de-excitation channels from upper laser level are negligible against the stimulated emission
Summary
Scattering materials have attracted attention as laser sources due to potential applications such as high definition speckle-free phosphors, holographic laser displays, optical or chemical sensors for medical diagnosis, nanoscale lithography, miniature spectroscopy, etc [1,2,3]. Of the absolute stimulated emission energy (and slope efficiency), laser threshold energy and their dependences with the pump spot size and pump wavelength, and of the time dynamics of emission pulses and spatial distribution of pump and emission beams. In this review we would like to clarify some of the basic properties of random lasing in rare earth-activated materials For this purpose we will use a variety Nd3+ doped crystal powders (in the 4F3/2→4I11/2 emission band of Nd3+ ions around 1.064 μm) with different Nd3+ concentrations and different grain sizes, with transport lengths in the 10-100 micron range. The investigated properties are the emission spectrum, the threshold energy and the absolute emitted energy and the slope efficiency, and their dependence on pump beam area, pump wavelength, Nd3+ concentration and grain size. Intensity fluctuations with characteristic times less than 100 ps are observed when detection is spatially resolved which could be attributed to coherent wave interferences
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
