We have demonstrated the use of microspectroscopy for measuring the Cr3+ and Cr4+ fluorescence spectra in double-clad Cr:YAG crystal fiber. The emission spectra of Cr3+ and Cr4+ are detected from core and inner cladding. The Cr3+ spectrum in the inner cladding shows a broad-band emission from 650to950nm, while the emission of Cr4+ occurs in the range of 1.15–1.55μm with a peak around 1.22μm. The characteristic of Cr ion at high-field sites shows a narrow-band emission (E2→A24 for Cr3+; E1→A23 for Cr4+), whereas that at low-field sites shows a broad-band emission (T24→A24 for Cr3+; T23→A23 for Cr4+). The emission intensity ratio of high-field sites to low-field sites in the inner cladding with different compositions has been investigated. It varies from 20% to 29% for Cr3+ and from 7.1% to 11.3% for Cr4+ when the concentration of SiO2 increases from 26.9to43.0wt%.

We demonstrated an efficient, compact, and continuous-wave Raman crystal fiber laser (RCFL) using an intracavity and resonant χ(3) approach. The gain and nonlinear medium was Cr4+:Y3Al5O12 double-clad crystal fiber grown using the codrawing laser-heated pedestal growth technique. The RCFL threshold was only 50 mW, and the slope efficiency reached 14.3% above a pump power of 350 mW. The result is in good agreement with theory, which indicates a near-100% quantum efficiency of resonant stimulated Raman scattering.

No abstract

No abstract

We have demonstrated the use offluorescence confocal microscopy in mapping the Crt3 profile within the YAG crystalfiber. A sensirivity of 2.3xId6/cd was achieved, which is ten jold of magnitude better than that of electron probe micro -analysis.