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(b)
Figure 1: (a) the selective area ICP-QWI process; and (b) SEM
photograph of the extended-cavity laser. [1]
Prof. Mei Ting’s group in PhRC has pioneered the
research of plasma-based QWI technology and has
obtained several promising preliminary results. Using
Inductively Coupled Plasma (ICP) enhanced QWI,
we have demonstrated large bandgap energy blueshifts
(> 100 nm), selective area bandgap tuning and integration
of laser and low-loss waveguide (with losses less than
12.9 dBcm −1 ). Further study in ICP-QWI will be carried
out as part of the larger program to develop PIC.
Reference
[1] H.S. Djie, et al, “Photonic Integration using Inductively
Coupled Argon Plasma enhanced Quantum Well Intermixing”,
Electron. Lett., vol. 38, no. 25, pp. 1672-1673,
2002.
Development of High Power Laser Diode Arrays
Ast/P Tang Xiaohong
High power laser diode arrays are of great interest
because of their compact size and the numerous
applications in diode-pumped solid-state lasers,
Erbium-doped fibre amplifiers, space communication,
smart welding of metals and plastics, thermal printing
and medical treatment, etc.
In PhRC, laser diode bar arrays with optical powers in
excess of 20 watts in continuous-wave (CW) operation,
and a high slope efficiency of 1.1 W/A, have been developed.
The threshold current is about 6 A for a 19-emitter
array, and the threshold current density per device is as
low as Jth = 200 A/cm2 .
Fabrication of high power laser diode arrays involves
device design, material growth, post-growth processing,
device packaging and characterization. The materials
were grown with our own Metal-Organic Chemical
Vapour Deposition (MOCVD) system. The keys to
the success of this project are good material quality and
good packaging for thermal management, and most of all
the dedication of the research team consisting of Dr Bo
Baoxue, Dr Huang Gensheng, Dr Zhang Baolin, and
Dr Zhang Yuanchang.
Did You Know? One of the most powerful ultraviolet laser in the
world, (the 60-terawatt omega, at the Laboratory for Laser Energetics
at the University of Rochester, New York) is used to test fusion experiments.
In less than a billionth of a second, the laser sends the temperature
in a tiny pellet from just a few degrees above absolute zero
to nearly 30 million degrees Celsius—twice as hot as the core of the
sun. For this brief period of time the laser power is about 100 times the
peak power of the entire U.S. power grid.
(a)
(b)
Figure 1: (a) Laser bars in perspective (b) Laser bar under test on
a copper heatsink.
PHOTONIC MATERIALS & DEVICES RESEARCH September 2003 17