We have developed a commercial 4-kW fiber laser consisting of seven, 600-W modules whose outputs are combined
with a fused-fiber combiner. The system architecture has several practical advantages, including pumping with reliable
single-emitter diodes, monolithic fused-fiber construction (no free-space beams), and end pumping using a 91:1 pump
combiner (eliminating the need for complex pump/signal combiners). Typical results at 4-kW output power are a beamparameter
product of 2.6 mm-mrad, 8-hr power stability of < 0.5% rms, central wavelength of 1080 nm, and linewidth of
1.2 nm FWHM. These lasers have been incorporated into Amada machines used for cutting metal sheet and plate and
have been used to cut aluminum, mild steel, stainless steel, brass, titanium, and copper with a thickness up to 19 mm. A
world-record cutting speed of 62 m/min has been demonstrated for 1-mm aluminum sheet metal.
We report the development of fused-fiber pump and signal combiners. These combiners are enabling components of a ytterbium fiber-laser emitting 4 kW of 1080-nm radiation. The fiber-laser system consists of seven fiber laser modules and a 7:1 signal combiner. The laser modules are end-pumped by 90 915-nm JDSU L4 diode-lasers, yielding a nominal pump power of 900 W. The diode laser radiation is coupled into the laser fiber through a 91:1 fused-fiber pump combiner. The input fibers of this pump combiner are standard 105/125-um multimode fibers with an NA of 0.22. These fibers form a hexagonally packed fused-fiber bundle, which is tapered to match the cladding diameter of the laser fiber. Eighty-six percent of the light exiting the pump-combiner is emitted within an NA of 0.32, and all measurable power is emitted within an NA of 0.45. The typical insertion loss of the pump combiners is <1%. The high-brightness radiation of seven laser modules is combined into a single output fiber using a 7:1 fused-fiber signal combiner providing a total power of >4 kW in the single output beam. The beam parameter product of the combined output was 2.5 mm-mrad. The low insertion loss of < 2% indicates that the signal combiner is suitable to handle even higher laser powers.
Multipath resonators are well known as optical delay lines. By many zick-zack rays between two mirrors large optical path lengths can be obtained. This passive system can be converted into a laser oscillator by closed ray paths and a Nd:YAG crystal at one mirror. Optical pumping occurs by directly coupled diodes at the reflection points. Very efficient (more than 40% optical/optical) and compact systems up to 20 W, with the beam propagation factor m2 < 3 were generated. Q-switching and internal frequency doubling were also demonstrated. The fundamental physics of this system including the transverse mode-locking at the degeneration points of the resonator was investigated, experimentally and theoretically.
This paper reports optical and electrical performance study of high Tc superconductors, especially YBaCuO film. The behavior of high Tc superconductors at or near Tc was studied in detail. A high Tc superconducting transition-edge bolometer has been fabricated from YBaCuO thin film on a (100) SrTiO3 substrate. The performance of the bolometer was studied. By using of the detectors, we also studied the photoresponse of YBaCuO film to He-Ne laser and far infrared laser. At or near the middle point of the film's transition temperature, the obtained voltage response signal of YBaCuO film to 1.5 mW He-Ne laser chopped at a frequency of 0.1 Hz is 10 mV. The relationship between the photoresponce signal to material, temperature and chopping frequency was studied in detail.
This paper reports the Preliminary results of a high Tc superconductive transition-edge bolometer for millimeter and submillimeter waves outputed from an optically pumped far infrared laser. The bolometer was fabricated by using of a photolithographic YBaCuO thin film on a (100) SrTiO3 substrate at liquid nitrogen (LN) temperature as the fast sensitive detector.
This paper reports the divergence study of optically pumped far infrared laser with wave lengths of 118 micrometers , 447 micrometers , and 890 micrometers . A special device of scanning, recording and detecting system is used in order to obtain the laser beam divergence.
This paper reports the photoresponse of photolithographic YBaCuO superconducting film at liquid nitrogen (LN) temperature range under the irradiation of He-Ne laser and optically pumped far infrared laser. The relationship of laser photoresponse of YBaCuO film to chopping frequency is studied theoretically and experimentally in detail.
Pulsation behaviors of optically pumped HCOOH 433 micrometers , CH3I 447 micrometers , and CH2CF2890 micrometers sub-millimeter laser were experimentally studied. Pulsation frequency varies continuously with tilting the output cavity mirror or changing the gas pressure. Two-frequency pulsation was observed and it developed easily into chaos by condition changing such as cavity tilting. Laser chaos was not sensitive to condition changing and was able to persist for quite a long time.