Akira Fujisaki

High-power Cascaded Raman Fiber Laser with 41-W output power at 1480-nm band

A cascaded Raman laser with 41-W CW output at 1480-nm band was demonstrated by a 65-m silica-based highly nonlinear fiber as the Raman gain medium.

High-power erbium-doped fiber amplifier pumped by wavelength multiplexed semiconductor laser diode unit

High-power optical fiber amplifiers (OFAs) are needed in various optical transmission systems: wavelength-division multiplexing (WDM) systems, large passive splitting systems, long-haul repeaterless systems, analog distribution systems, etc. The use of high power pumping sources is one of the most important factors for high-power OFAs. High-power OFAs with various pumping sources are reported. We demonstrate a high-power Er-doped fiber amplifier (EDFA) pumped with wavelength multiplexed light from a MQW semiconductor laser diode unit.

2D/3D laser cutting of carbon fiber reinforced plastic (CFRP) by fiber laser irradiation

We report on the laser cutting of carbon fiber reinforced thermo-plastic (CFRTP) and carbon fiber reinforced plastic (CFRP) with a cw IR fiber laser (average power: 2 kW). CFRTP and CFRP are a composite material which contains carbon fibers and binding plastics. A well-defined 2D laser cutting of CFRTP and CFRP flat plates which were free of debris around the groove was performed by the laser irradiation with a fast beam galvanometer scanning on a multiple-scan-pass method. The area of laser-induced damages in the samples was observed by microscopic X-ray Computed Tomography. Laser cutting with a high speed beam scanning exhibits a clean top and an excellent sidewall quality along with a negligible heat affected zone. In addition, the laser cutting of CFRP for a three-dimensional molded sample was performed with a five-axis laser cutting machine.

Laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) by single-mode fiber laser irradiation

We report on the laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) with a cw IR fiber laser (single-mode fiber laser, average power: 350 W). CFRTP is a high strength composite material with a lightweight, and is increasingly being used various applications. A well-defined cutting of CFRTP which were free of debris and thermal-damages around the grooves, were performed by the laser irradiation with a fast beam galvanometer scanning on a multiple-scanpass method.

High power single-mode fiber laser and its application to metal and non-metal materials

The power level of Yb doped fiber lasers which operate in continuous wave mode has been increasing in recent years and various kinds of applications using high power single-mode fiber lasers that oscillate in 1microns wavelength range were reported. Single-mode fiber laser that has excellent beam quality of less than 1.1 M2 value with kW class average power can be focused to tens of microns diameters and its optical power density at the focus point is more than 1×108 W/cm2. In this power density range, the interaction between 1microns laser light and matter, not only metal materials but non-metal materials, is completely different from that of lower level. The power density initiates laser processing of copper that has relatively high reflectivity at this wavelength range among metals and alumina base plate with over 90% reflectivity. Other interesting material which can be processed by this energy level is carbon fiber reinforced plastics (CFRP). On the other hand, for industrial application and further processing investigation, modulation speed is one of the most important factors because that relates to processing speed and precise control of laser energy input to a material. In this paper, we report on the power dependence of some material processing of copper wafer welding, alumina base plate scribing, and CFRP cutting using single-mode fiber laser which is capable of over 1kW peak power operation and has rapid switching time below 5 micro seconds.

Laser trepanning of CFRP with a scanner head for IR and UV lasers

The dual beam of cw-350 W single-mode near-IR fiber laser and ns-pulsed-35 W UV laser were used in the experiments for cutting. The laser beam on the sample surface was scanned with a galvanometer scanner and focused with the f-theta lens of 400 mm focal length for IR and UV laser irradiations. A prototype remote scanner head for the multiple laser irradiations has been developed for a high-quality and high-speed laser processing of carbon fiber reinforced plastics (CFRP). In this paper, we report on the laser trepanning of circular patterns on CFRP.

High power single-mode fiber laser and a multi-mode delivery cable

Over 500W output power Yb doped single-mode fiber laser demonstrates excellent beam quality of less than 1.1 M2 value. Use of single mode fiber as delivery cable enables small spot-size; however delivery length is limited by SRS in fiber. To mitigate this characteristic, use of multi-mode fiber for delivery is one of approach. We present our design of 500W single mode fiber laser and beam quality measurement of multi-mode delivery fiber. How they vary, how we can homogenize beam depend on different condition of connection style, etc. We also present material process results in different beam performance.

High quality and high speed cutting of Al2O3 substrate with single mode fiber laser

Alumina ceramic (Al2O3) is one of high performance thermal conducting substrate then widely used for several electric devices such as LED. One of key process, which will sometimes limits their productivity in LED production is singulation. As a conventional method, blade cutting is well known technique; however there are several disadvantages such as slow speed of 10mm/s and wear of blade due to physical contact. To solve this problem, laser cutting is one of ideal technique; however alumina ceramics have higher reflection for conventional lasers for material process.Recent progress of single mode fiber lasers enables remarkably high brightness at focal point. The power density reaches higher than 107 W/cm2, this power level make us possible to initiate cutting of alumina substrates both at high speed and high quality even though they have a poor absorbance at λ = 1084 nm, which is the wavelength of our fiber lasers. We have developed 500W single mode fiber laser and demonstrated alumina ceramics substrates singulation at more than ten times faster than the speed of the mechanical cutting. Excellent cutting quality was demonstrated at a single sweep process. A pretty smooth cutting surface and dross-free cutting does not require any additional finishing work.Alumina ceramic (Al2O3) is one of high performance thermal conducting substrate then widely used for several electric devices such as LED. One of key process, which will sometimes limits their productivity in LED production is singulation. As a conventional method, blade cutting is well known technique; however there are several disadvantages such as slow speed of 10mm/s and wear of blade due to physical contact. To solve this problem, laser cutting is one of ideal technique; however alumina ceramics have higher reflection for conventional lasers for material process.Recent progress of single mode fiber lasers enables remarkably high brightness at focal point. The power density reaches higher than 107 W/cm2, this power level make us possible to initiate cutting of alumina substrates both at high speed and high quality even though they have a poor absorbance at λ = 1084 nm, which is the wavelength of our fiber lasers. We have developed 500W single mode fiber laser and demonstrated alumina ceramics substrat...

High-power polarization-maintaining dispersion-shifted EDFA

Summary form only given. We have developed fully engineered polarization-maintaining and dispersion-shifted Er-doped fiber amplifiers (EDFAs) using polarization-maintaining and absorption-reducing (PANDA) and dispersion shifted fiber structure erbium-doped fiber (PMDS-EDF).