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Fiber Lasers with Air Cool 300 W, Water Cool 500 W
Single-mode and 2 kW Multi-mode for Material Processing

1.

INTRODUCTION

Fiber lasers have an ideal performance with respect tohigh beam quality, to long time stability, to high reliability
and to high efficiency and also make the direct fiber delivery to processing targets available. With such excellent
features, the market size of fiber lasers is expanding year
after year. The popularity of, especially, the fiber lasers
with high output of more than 1 kW has been increasing
rapidly in the field of metallic material processing whereexisting carbon dioxide lasers or solid-state lasers weremainly used.
We, as a pioneer amongst domestic companies, haveworked early in research, in development and in massproduction manufacturing in the technologies of special
fibers, optical components, pumping semiconductor
lasers, fiber splicing, and also fiber amplifiers and fiber
lasers using such technologies.

2.

Figure 1 Air-cool-type fiber laser with 300 W output.
(Upper: power supply, Lower: optical section)

SINGLE-MODE FIBER LASER

The single-mode fiber laser which achieves diffractionlimited focusing property is commercialized in two types:
air-cool-type with 300 W output and water-cool-type with
500 W output.
The key specifications of these single-mode fiber laser
are illustrated in Table 1.
Table 1

Key specifications of single-mode fiber laser.

Items

Specifications

Center wavelength1084 ± 5 nm

Beam quality (M²)

< 1.1

Modulation rate

up to 50 kHz

Guide light

660 nm

Notes

Red

Figure 2 Water-cool-type fiber laser with 500 W output.

Figure 2 shows the water-cool-type fiber laser with a500 W output. It achieves a high processing performancefor high reflecting materials such as copper, aluminum orceramics because the beam intensity of focusing
becomes over 1 x 108 W/cm2. Figure 3 shows the crosssection of the processing mark at the evaluation for penetration into tough pitch copper C1100 and Figure 4 shows
the cutting surface of full-cut alumina.

Figure 1 shows external view of the air-cool-type singlemode fiber laser with 300 W output. It has an output fiberwith approx. 12 μm of mode field diameter and more than
20 m of delivery is available.

Furukawa Review, No. 43

201351Fiber Lasers with Air Cool 300 W, Water Cool 500 W Single-mode and 2 kW Multi-mode for Material Processing

connected to this laser combiner and 2 kW output with50 μm core diameter is obtained. Also, delivery fiber
length to more than 20 m is attained.
Table 2 illustrates the key specifications of a kW fiber
laser and Figure 6 shows the external view of the fiber
laser with 2 kW output.
Table 2Figure 3 Penetration into tough pitch copper.
(Focusing length f = 100 mm)

Key specifications of kW fiber laser.

Items

Specifications

BPP< 2.2 mm・mrad

Modulation rateup to 50 kHz

Guide light660 nmRed1000(W) x 520(D) x 850(H) mm

Opticalsection

SizeNotes

200 µmFigure 4 Example for the cut processing on alumina.
(t = 500 μm)
Figure 6 Fiber laser with 2 kW output.

kW MULTIPLEXING BY LASERCOMBINER
12 μm NA=0.08

50 μm NA=0.22

Figure 7 shows that the relationship between the driving current and the laser output characteristics of pumping a semiconductor laser, and a conversion efficiency ofthe optical output towards the power supplied to thediode at 2 kW output was as good as 27.3%.

SM fiber laser
SM fiber laser
SM fiber laser

Laser combiner

Figure 5 Configuration of a laser combiner and a kW fiber laser.

Output power (W)SM fiber laser

2500

30%

2000

25%
20%

1500

15%
1000

10%

500

Similar to TFB (Taper Fiber Bundle) used to lead pumping
light of the fiber laser oscillator into cladding, a laser combiner is a beam combiner which is achieved by applying
fused taper technique for optical fibers. As shown inFigure 5, high efficiency of more than 95% is achieved
when combining seven single-mode inputs with 12 μm
core diameter and NA=0.08 into one multi-mode fiberwith 50 μm core diameter and NA=0.22.
For the commercialized 2 kW fiber laser, 4 pcs of singlemode fiber lasers with output of 500 W class each are

Efficiency (%)

3.

5%

00%
02

468
Pump drive current (A)1012Figure 7 Output characteristics of 2 kW fiber laser.

As shown in Figure 8, M2 of this laser is 4.66 and theemission wavelength of the laser is 1084 nm, so that theBPP (Beam Parameter Products) is calculated as 1.609
mm · mrad.

Furukawa Review, No. 43

201352Fiber Lasers with Air Cool 300 W, Water Cool 500 W Single-mode and 2 kW Multi-mode for Material Processing

Penetration depth [μm]6000
SUS304
A5052
C1100

5000
4000
3000
2000
1000
00

20

40

60

80

100120

Welding Speed [m/min]Figure 8 Beam quality of 2 kW fiber laser.

The kW output fiber laser has a multi-mode output anda power density of its focused beam which is lower thanthat of the single-mode fiber laser described earlier, however, since the output power becomes higher, on theother hand, the processing performance for the highreflecting materials is improved1). Figure 9 shows the penetration characteristics into stainless (SUS304), aluminum(A5052) and tough pitch copper (C1100) irradiated by acondenser lens with a focusing length f = 200 mm
We have started to sell this kW fiber laser for metallic
processing use such as sheet-metal cutting or welding
processing.

Figure 9 Penetration characteristics into various metals.
(Focusing length f = 200 mm)

REFERENCES1) Journal of JLPS Vol.19 No.1 p.7 (2012)

For more information, please contact:
Planning & Administration Department,
Telecommunications Company
Tel: +81-3-3286-3768 Fax: +81-3-3286-3708
E-mail: Fiberlaser_bsgr@furukawa.co.jp

Furukawa Review, No. 43

201353