光技術情報誌「ライトエッジ」No.39（2013年6 月発行）
レーザーディスプレイ国際会議 (2012年4月)
Multi-Watt Class, Red, Green, and Blue, Direct Emitting and
Frequency Doubled Laser Diodes for Display Applications
Hidekazu Hatanaka 1), Gregory T. Niven 2)
Development Division, USHIO INC.,
1194, Sazuchi, Bessho-cho, Himeji, Hyogo 671-0224, Japan, +81-79-252-4318 (phone) -4626(fax)
h.hatanaka@ushio.co.jp 2) Necsel Intellectual Property
1) SSLS
ABSTRACT
We provide multi-watt class red, green, and blue lasers as a solid state light source solution for projectors and
other display applications. Life tests demonstrated over 38,500 hours of actual operation for green and blue lasers.
The test for red laser has passed 7,000 hours under acceleration test condition and is going on.
1. INTRODUCTION
Solid state light source based on semiconductor
technology has a lot of attractive properties as a
light source for projectors 1,2） such as long life and
quick start. We provide multi-watt class red,
green, and blue lasers as a solid state light source
solution. The wavelengths of these red, green, and
blue lasers are 639 nm, 532 nm, and 465 nm,
respectively. The red (Model NECSEL-640-5000) is
a direct-emitting laser diode with continuous wave
output power of 5 W. Both green (Model
NECSEL-532-3000) and blue (Model NECSEL-465-3000)
are Necsel type laser diodes with output power of
3 W 3,4）. This paper reviews the technology used
for these laser products and discusses the
reliability based on measured life test data.
is composed with an infrared (IR) VCSEL (Vertical
Cavity Surface Emitting Laser) array and a
nonlinear optical crystal (PPLN：Periodically Poled
Lithium Niobate) for blue of 465 nm and green of
532 nm. For both green and blue Necsel type laser
diodes of the first generation, diamond was used as
the submount material for excellent thermal
conductivity. The life test result shown in Fig. 2
demonstrates that the laser output power is almost
the same as the initial after 35,000 hours. This
corresponds to over 10-year of use if it is used ten
hours per day,seven days per week, and 50 weeks
per year, which would be very typical for
projection applications.
(a)
Table.1 Specifications of Necsel red, green, and blue laser
diodes
Specifications
Red
Green
Blue
Laser Power［ W］
5
3
3
Wavelength
［ nm］
639
532
465
2. Laser structures and Life tests
Infrared
VCSEL
Array
Frequency
Doubler
(PPLN)
Output
Coupler
(VBG)
(b)
This chapter reviews typical properties and life
test results of each laser.
2.1 Green and blue lasers
Both green and blue are unique Necsel-type laser
diodes with output power of 3 W shown in Fig. 1 [3,4].
The Necsel-type laser diode is an intra-cavity,
frequency doubled type visible laser diode, which
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Fig.1 Necsel type green and blue lasers. (a) Schematic of
the laser, and (b) photo of green laser in operation.
光技術情報誌「ライトエッジ」No.39（2013年6月発行）
レーザーディスプレイ国際会議(2012年4月)
Normalized Laser Power
1.4
1.2
Initial Laser Power : 3W
1.0
0.8
0.6
0.4
Failure Definition :
0.5
0.2
0.0
24,000
28,000
32,000
36,000
40,000
44,000
Time（hours）
Fig.2 Life test result of green laser (Gen.1).
1.4
Normalized Laser Power
1.2
1.0
Initial Laser Power : 3W
0.8
0.6
0.4
Failure Definition :
0.5
0.2
0.0
8,000
12,000
16,000
20,000
Time（hours）
The life test result in Fig. 3 demonstrates that
the laser output power is almost the same as the
initial after 19,400 hours under the accelerated test
condition of Tnecsel = 50℃, corresponding to 38,800
hours for the rated temperature of Tnecsel =
40 ℃.
The on-off test result in Fig.4 demonstrates that
the laser output power is almost the same as the
initial for the third generation after over 25,000
on-off cycles. Thermal stress was applied to
confirm the stable operation at a variety of
installation sites. The initial laser power level was
set at 3 W. The temperature of T necsel moved
between 28 ℃ and 40 ℃ in one on-off cycle. Each
on-off cycle has typically a 20-minute on-state to
heat the laser by self-generating heat and a
20-minite off-state to cool the laser by forced air
flow. The result shows that after over 25,000 on-off
cycles, the laser output power is almost the same
as the initial. This corresponds to over 14-year of
use if these are used five times on-off per day,
seven days per week, and 50 weeks per year,
which would be very typical for cinema projection
applications.
2.2 Red laser
Fig.5 shows direct emitting LD; (a) with
collimation lens option, and (b) with fiber coupling
option.
Fig.3 Accelerated life test result of green laser (Gen.3).
Acceleration factor is two when Tnecsel = 50℃, which is
higher than the rating of 40 ℃ by 10 ℃.
(a)
1.4
Normalized Laser Power
1.2
1.0
Initial Laser Power : 3W
0.8
>25,100cvcles
0.6
0.4
Failure Definition :
0.5
(b)
0.2
0.0
5,000
10,000
15,000
20,000
Time（hours）
Fig.4 On-off test result of blue laser (Gen.3). Test condition for
one cycle is 20 minutes on and 20 minutes off typically.
Generation 3 in Fig s . 3 and 4 is the pres ent
product employing Cu-plated AlN as the submount
material for matching of coefficients of thermal
expansion with the GaAs die and copper cooling plate.
Fig.5 Red laser diodes. (a) Collimation lens option, and
(b)Fiber coupling option.
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光技術情報誌「ライトエッジ」No.39（2013年6 月発行）
レーザーディスプレイ国際会議 (2012年4月)
Fig.6 demonstrated that the laser output power
is stable over 7,000 hours after some decrease
during initial hundreds hours under an output
power acceleration test condition of 6 W which is
higher than the rated 5 W by 1 W. The
acceleration factor is not discussed concretely
here. However, it looks very promising to operate
the laser much longer time at the rating of 5 W.
Normalized Laser Power
1.2
Initial Laser Power : 6W
1
0.8
0.6
Failure Definition :=0.5
0.4
0.2
0
0
1,000
2,000 3,000 4,000 5,000 6,000 7,000
Time（hours）
Fig.6 Life test result of red laser diode. Test condition for
laser power of 6 W is higher than the rating of 5 W by 1 W.
3. Conclusions
The life tests demonstrated over 38,500 hours of
actual operation for both green and blue laser
diodes. The test for red laser has passed 7,000
hours under acceleration test condition and is
going on. We believe these reliable lasers are
suitable for light sources for projectors and other
displays.
References
1）B. D. Silverstein, et al., A Laser-Based Digital Cinema
Projector , in Proc. SID 11, Vol. 42, Issue 1, pp. 326-329
(2011).
2）P. Janssens, et al., Fiber-Coupled Laser Cinema Projector , in
Proc. IDW 11, pp. 1885-1888 (2011).
3）G. Niven and A. Mooradian, Trends in Laser Light Sources for
Projection Display , in Proc. IDW 06, pp. 1936‒1939 (2006).
4）H.Hatanaka and G Niven, Multi-Watt Class, Red, Green, and
Blue Direct Emitting and Frequency Doubled Laser Diodes , in
Proc. IDW 11, pp. 2052-2056 (2011).
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