Compact 589 nm yellow source was reported and generated from intracavity frequency-doubling of c-cut YVO 4 / Nd:YVO 4 /YVO 4 Raman laser. A Cr 4+ :YAG/YAG composite was adopted for compact passively Q-switching operation. Double-end composited Nd:YVO 4 crystal was designed to reduce the thermal effect and increase Raman crystal length. Both noncritical phase-matching (NCPM) LBO crystal and critical phase-matching (CPM) BBO crystal were used as frequency doubling crystal for comparison. 780 mW output power of 589 nm yellow emission was achieved with an incident pump power of 16 W. The pulse repetition frequency and pulse width were 41 kHz and 3.6 ns at the maximum output power, respectively. The results show passively Q-switched operation provides a compact method to obtain 589 nm yellow emission.
Smart hospitals are important components of smart cities. An intelligent medical system for brain tumor segmentation is required to construct smart hospitals. To achieve intelligent brain tumor segmentation, morphological variety and serious category imbalance must be managed effectively. Conventional deep neural networks have difficulty in predicting high-accuracy segmentation images due to these issues. To solve these problems, we propose using multimodal brain tumor images combined with the UNET and LSTM models to construct a new network structure with a mixed loss function to solve sample imbalance and describe an intelligent segmentation process to identify brain tumors. To verify the practicability of this algorithm, we used the open source Brain Tumor Segmentation Challenge dataset to train and verify the proposed network. We obtained DSCs of 0.91, 0.82, and 0.80; sensitivities of 0.93, 0.85, and 0.82; and specificities of 0.99, 0.99, and 0.98 in three tumor regions, including the
whole tumor
(
WT
),
tumor core
(
TC
), and
enhanced
tumor
(
ET
). We also compared the results of the proposed network with those of other brain tumor segmentation methods, and the results showed that the proposed algorithm could segment different tumor lesions more accurately, highlighting its potential application value in the clinical diagnosis of brain tumors.
Diode end-pumped Nd,La:CaNb2O6 self-Raman laser with acousto-optic Q-switching was successfully demonstrated for the first Stokes wave generation at 1,174 nm. A 1.0 at.% Nd3+ and 1.0 at.% La3+-doped CaNb2O6 crystal in dimensions 3 × 3 × 14.3 mm3 was used as the self-Raman laser crystal. Doping 1 at.% La3+ ions into this crystal could subdue the fluorescence quenching caused by cross-relaxation between Nd3+ ions and finally improve the laser output performance. Under the incident pump power of 9.9 W, the first Stokes wave at 1,174 nm with a maximum output power up to 928 mW was obtained, with the diode to Stokes conversion efficiency of about 9.4%. The results show that the Nd,La:CaNb2O6 is also a promising self-Raman crystal for efficient fundamental and Raman laser operation.
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