A conical refraction (CR) laser based on a separate gain medium (Nd:YVO<sub>4</sub>) and an intracavity CR element (KGW) was demonstrated. The decoupling of the gain and CR media enabled the laser to produce a well-behaved CR laser beam with excellent quality, while reducing the complexity of the pumping scheme. The proposed laser setup has the potential for power scaling using the efficient diode pumping approach and the properties of the generated CR beam are independent from the laser gain medium.
We have demonstrated the highest conical refraction (CR) laser output power to date by placing a CR crystal inside of a diode-pumped Nd:YVO laser cavity. The CR crystal did not have a significant influence on laser output power as well as efficiency. The CR laser produced the maximum output power of 3.68 W with the slope efficiency of 42 % and opticalto- optical efficiency of 34 %. Therefore, this approach could be an attractive pathway for further power scaling of the CR lasers.
A new heterostructure based on Al<sub>x</sub>In<sub>1-x</sub>N/GaN high electron mobility transistor (HEMT) on SiC substrate has been
proposed for high frequency, where it offers the best performance in comparison to other two heterostructures like on
Al<sub>x</sub>Ga<sub>1-x</sub>N/GaN and In<sub>x</sub>Ga<sub>1-x</sub>N/GaN. We have investigated the effect of different higher output characteristics in
comparison to conventional Al<sub>x</sub>Ga<sub>1-x</sub>N/GaN and In<sub>x</sub>Ga<sub>1-x</sub>N/GaN with the Al<sub>x</sub>In<sub>1-x</sub>N/GaN heterostructure, where the drain
current is maximum for Al<sub>x</sub>In<sub>1-x</sub>N/GaN and Al<sub>x</sub>Ga<sub>1-x</sub>N/GaN heterostructure HEMT respectively for the same barrier
thickness and for the same gate source voltage.