At SPIE 2020 conference, we presented a blue diode laser that provides 200W output from a 200μm core diameter 0.22 NA fiber. Blue laser with high power and high brightness is the best choice for higher efficiency demanded by industrial processing. Based on 7 modules each provides 160W from a 105μm core diameter 0.22 NA fiber (NA 0.15/0.22 power ratio >93%), using fiber beam combining, 1000W output is achieved from a 330μm core diameter 0.22 NA fiber. And the aging test of 160 W unit modules was carried out. 1000W high brightness blue laser source is an ideal choice for processing (welding, 3D printing, etc) of non-ferrous metals, especially copper.
In order to optimize the output parameters of 808nm array of high-power microchannel heat sink package, the fluid thermodynamic characteristics of 50 × 10 array were simulated. The thermal distribution of the simulation results was used to guide the array assembly. The spectral characteristics of each bar in the stacked array were observed by near-field fiber scanning probe. The simulation results show that the flow rate of the stacked bar decreases gradually from bottom to top, the temperature of the bar increases gradually, and the flow rate of each stacked bar decreases slowly as it is far away from the water outlet. When the flow rate at the entrance of the stack array is 10 L/min, the temperature difference between the bottom and top bar of a single stack array is 13.1 °C, the flow rate difference is 0.24 L/min, and the FWHM width of the stack array spectrum can reach 4.5nm. The temperature of the active region is calculated by measuring the wavelength shift of each bar in a single stacked array, and the results are consistent with the simulation results. The spectral characteristics of the array can be effectively improved by assembling the array according to the temperature distribution.
High power wavelength-stabilized 976nm diode lasers attract more attention recently with the development of higher power, higher efficiency and higher brightness fiber lasers. The wide spectrum of a high-power diode laser without wavelength stabilization (about 5 nm), together with thermal shift at about 0.3 nm/°C, strongly limits the conversion efficiency benefits at 976 pumping. In this paper, we will report the development of kilowatt wavelength-stabilized CW and QCW diode lasers at BWT.
With certain emitter beam quality and BPP allowed by fiber, we have derived a spatial beam combination structure that approaches the BPP limit of the fiber. Using the spatial beam combination structure and polarization beam combination, BWT has achieved 1.1KW output from a fiber (one end coated) with NA 0.22 and core diameter of 200μm. The electro- optical efficiency is nearly 47%. Multiple emitters with wavelength of 976nm are packaged in a module with size of 600 ×350×80mm3.
With continuous increase in output power of fiber lasers, small volume, low weight, high electro-optic efficiency and high brightness diode laser pump source has become the trend of development. Using spatial beam combining and polarization beam combining methods, BWT has developed a compact pump laser achieving 600W level out of a fiber of 0.22 NA and 200 μm core diameter. At 12A, electro-optical efficiency is higher than 49%. Its brightness is higher than that of the commercially available 158W pump from BWT.
Proc. SPIE. 9733, High-Power Diode Laser Technology and Applications XIV
KEYWORDS: Energy efficiency, Diffraction, Mirrors, Polarization, High power lasers, Reflectivity, Semiconductor lasers, Collimation, High power fiber lasers, Beam shaping, Electro optics, Diffraction gratings
Spectral beam combination expands the output power while keeps the beam quality of the combined beam almost the same as that of a single emitter. Spectral beam combination has been successfully achieved for high power fiber lasers, diode laser arrays and diode laser stacks. We have recently achieved the spectral beam combination of multiple single emitter diode lasers. Spatial beam combination and beam transformation are employed before beams from 25 single emitter diode lasers can be spectrally combined. An average output power about 220W, a spectral bandwidth less than 9 nm (95% energy), a beam quality similar to that of a single emitter and electro-optical conversion efficiency over 46% are achieved.
In this paper, Rigorous Coupled Wave analysis is used to numerically evaluate the influence of emitter width, emitter pitch and focal length of transform lens on diffraction efficiency of the grating and spectral bandwidth.
To assess the chance of catastrophic optical mirror damage (COMD), the optical power in the internal cavity of a free running emitter and the optical power in the grating external cavity of a wavelength locked emitter are theoretically analyzed.
Advantages and disadvantages of spectral beam combination are concluded.