Book contents
- Frontmatter
- Contents
- Preface
- 1 The need for compact blue-green lasers
- Part 1 Blue-green lasers based on nonlinear frequency conversion
- Part 2 Upconversion lasers: Physics and devices
- Part 3 Blue-green semiconductor lasers
- 9 Introduction to blue-green semiconductor lasers
- 10 Device design, performance, and physics of optical gain of the InGaN MQW violet diode lasers
- 11 Prospects and properties for vertical-cavity blue light emitters
- 12 Concluding remarks
- Index
10 - Device design, performance, and physics of optical gain of the InGaN MQW violet diode lasers
Published online by Cambridge University Press: 07 December 2009
- Frontmatter
- Contents
- Preface
- 1 The need for compact blue-green lasers
- Part 1 Blue-green lasers based on nonlinear frequency conversion
- Part 2 Upconversion lasers: Physics and devices
- Part 3 Blue-green semiconductor lasers
- 9 Introduction to blue-green semiconductor lasers
- 10 Device design, performance, and physics of optical gain of the InGaN MQW violet diode lasers
- 11 Prospects and properties for vertical-cavity blue light emitters
- 12 Concluding remarks
- Index
Summary
OVERVIEW OF BLUE AND GREEN DIODE LASER DEVICE ISSUES
In this chapter we focus chiefly on the device science and engineering features of the violet edge-emitting InGaN MQW diode lasers. The extraordinary progress made with these devices since 1999, spearheaded by Nakamura and coworkers, seems to assure them an important place in future optoelectronics technology (Nakamura, 1999). By 2001, approximately half a dozen research groups reported achieving lifetimes of hundreds to a thousand hours for cw room-temperature operation, although the extrapolated lifetime of 15 000 hours at Nichia remained unequalled. Among the other groups we mention those at the laboratories of Sony, Toyoda Gosei, NEC, and Sharp in Japan, Samsung in Korea, and Xerox PARC, Cree Lighting, and Agilent Technologies in the USA.
A number of the core issues that intertwine the design, performance, and the physics of operation of the nitride lasers will be discussed in this chapter. We will focus on representative heterostructures that encompass the requirements of joint electronic and optical confinement, comment on some fabrication techniques, and highlight continuing challenges. The last include questions concerning the high threshold current density and the continued efforts to create artificial substrate templates for reducing the misfit (threading) dislocation density for improved device performance and lifetime. At a more fundamental level, there is evidence that the InGaN alloy which forms the optically-active QW medium has characteristic compositional disorder that impacts the gain spectrum of the laser. This feature, which increases in seriousness with the indium concentration, may restrict the operation of the devices at practical threshold current densities to the violet, leaving the longer blue and green regions to await future developments, perhaps involving complementary material approaches.
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- Information
- Compact Blue-Green Lasers , pp. 487 - 516Publisher: Cambridge University PressPrint publication year: 2003