The research team of Professor Wang Jun from the School of Electronic Information of Sichuan University and Suzhou Everbright Photonics Co., Ltd. proposed a method to expand the longitudinal gain based on multi-junction VCSEL to increase the power of single-mode VCSEL, and constructed a multi-junction VCSEL The mode analysis model solves the problem that the single-mode power is difficult to break through the level of about 10 mW. Under DC drive, a single-base transverse mode laser output of 20.2 mW is achieved, with a power conversion efficiency of 42% and a divergence angle of 9.8° (1/ e 2 ) and 5.1° (FWHM). This is the highest single-mode power of a single VCSEL to date, and its power value is nearly twice the existing single-mode power record.

Fiber-coupled diode modules have various applications in material processing and fiber laser pumping because of their high efficiency and high reliability. Commercial fiber-coupled diode modules using spatial beam combining and polarization beam combining cannot be employed in high-brightness applications, for example metal cutting, which demands a laser power exceeding 1 kW with a BPP of a few mm*mrad. Dense wavelength beam combining (DWBC) technology showed the possibility of further scaling-up the output power of fiber-coupled diode modules while maintaining the same beam quality that allows for fiber-coupled diode modules to be used in high-brightness applications. The efficiency, reliability, and brightness of fiber-coupled diode modules can be improved by using single emitters instead of laser diode bars as power sources in DWBC. Two types of high-brightness 100 µm/0.22 NA 2 kW fiber-coupled diode modules employing single-emitter-based DWBC technology, which have a wavelength range from 953 to 991 nm with 50% efficiency and a narrower wavelength range with 48% efficiency respectively, were developed for material processing and Raman fiber amplifier pumping. Furthermore, we combined 15 high-brightness 100 µm/0.22 NA 1.4 kW fiber-coupled diode modules into a 600 µm/0.22 NA fiber, achieving more than 22 kW at the output.