All III-Arsenide Low Threshold InAs Quantum Dot Lasers on
InP(001)
Jinkwan Kwoen, Natalia Morais, Wenbo Zhan, Satoshi Iwamoto and Yasuhiko
Arakawa
This study investigates the development of InAs quantum dot (QD) lasers
on a InP(001) substrate, utilizing only III-arsenide layers. This
approach avoids the issues associated with the use of phosphorus
compounds, which are evident in the crystal growth of conventional
C/L-band QD lasers, making the manufacturing process safer, simpler, and
more cost-effective. The threshold current density of the fabricated QD
laser was 633 A/cm2, which is the lowest value for QD
lasers in the 1.6 μm-wavelength region. This result suggests a high
cost-effectiveness and paved the way toward a large-scale production
technology for high-performing C/L/U-band QD lasers.
Introduction: Conventional-band (C-band) and long-band (L-band)
lasers used in optical communications are prevalent for long-distance
communication due to their minimal loss within optical fibers. These
lasers play a crucial role in enabling high-speed data transmission over
long distances [1, 2]. The potential applications of lasers extend
beyond traditional optical communications. Advancements in laser
technology have opened new possibilities, such as their use as gain
media for silicon photonics and as nonlinear optical components for
quantum computing[3, 4]. These emerging fields require lasers with
specific properties and capabilities. Quantum dot (QD) lasers have
attracted considerable interest in recent years due to their unique
characteristics. They exhibit features such as low threshold current
density, high-temperature stability, and exceptional emission efficiency
[5–7]. These attributes make them promising candidates for various
applications. InAs QDs on InP substrates have been extensively
researched for C/L-band QD lasers [8–10]. The combination of InAs
quantum dots and InP substrates has shown great potential for achieving
efficient lasing in the C and L wavelength bands.
However, it is generally standard to concurrently use group V materials,
arsenic and phosphorus, in the crystalline growth of C/L-band quantum
dot lasers via molecular beam epitaxy. The use of indium materials in
fabrication presents several challenges. The production of white
phosphorus, which is both spontaneously combustible and toxic,
complicates the manufacturing process and poses safety risks. Further,
the need for additional phosphorus supply equipment such as cells,
pumps, and safety traps increase both cost and process complexity.
Moreover, there is a need for precise control over the phosphorus and
arsenic mix during crystal growth. These issues can be mitigated by
using only Group III-Arsenide (III-As) materials. Without using
phosphorus, the manufacturing process becomes safer, simpler, and
cost-effective.