100-mW kink-free blue-violet laser diodes with low aspect ratio

Asano, T.; Tojyo, T.; Mizuno, Takashi; Takeya, M.; Ikeda, S.; Shibuya, Katsuyoshi; Hino, T.; Uchida, Shiro; Ikeda, Masao

doi:10.1109/jqe.2002.806213

Cited by 43 publications

(20 citation statements)

References 13 publications

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“…Thus, a new ridge structure in which both sides of the ridge stripe are covered with a stacked layer of Si on thin SiO 2 was developed to prevent the generation of kink [2,11]. As Si exhibits absorption loss in the 400-nm wavelength region, the first-order lateral mode can be effectively suppressed by selecting the thickness of SiO 2 appropriately.…”

Section: Transverse-mode Stabilizationmentioning

confidence: 99%

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High‐power GaN‐based semiconductor lasers

Ikeda¹,

Mizuno²,

Takeya³

et al. 2004

phys. stat. sol. (c)

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PACS 42.55.Px, 42.60.Lh, 78.66.Fd, 81.05.Ea, 81.15Gh GaN-based blue-violet lasers with a kink-free output power of higher than 150 mW have been successfully realized by adopting a new ridge structure and appropriately designing the beam divergence. The new ridge structure is a narrow 1.4 µm ridge covered with a stacked layer of Si on SiO 2 and the beam divergence half-angles parallel and perpendicular to the junction plane are set at 8° and 21°, respectively. These lasers have been operating stably for more than 500 h under 130-mW pulsed operation at 60 °C. The empirical activation energy of device lifetime under 30-mW continuous-wave operation is 0.32 eV.Introduction GaN-based high-power blue-violet laser diodes (BV-LDs) operating in the 400-410 nm wavelength band are promising light sources for large-capacity optical storage systems. The characteristics of BV-LDs have been improved remarkably since Nakamura et al. reported the first roomtemperature continuous-wave (CW) operation in 1996 [1]. Reliable BV-LDs with estimated lifetimes exceeding 10,000 h under 30-mW CW operation at 60 °C have been realized in recent years [2][3][4]. Although these devices can be readily used in high-density digital video recording systems [5], reliable BV-LDs capable of much higher output power will be required in the near future as the technology for optical disk systems extends to multi-layer disks and higher data transfer rates to facilitate higher densities and higher recording speeds.In designing a high-power laser suitable for use in optical disk systems, it is essential to maintain both a high kink level and a high catastrophic optical damage (COD) level of output power. These two levels are closely related to the optical confinement in the stripe of the laser structure, and hence to the beam divergence angles. The lifetime of BV-LDs is also governed by the density of dislocations within the stripe [6]. The stripes of current lasers typically contain significantly less than 100 dislocations, reduced from previously much higher numbers through the use of dislocation-reduction techniques such as epitaxial lateral overgrowth (ELO) [7,8], and lifetimes of over 1,000 h at 60 °C have already been achieved. However, even one dislocation in a stripe causes rapid degradation in other III-V laser diodes such as AlGaAs, GaInAsP and AlGaInP lasers. The remarkably long lifetimes and resilient nature of GaN-based lasers is therefore apparently associated with the inherent rigidity of this material system.In this paper, the kink and COD levels of a laser structure optimized for obtaining high output powers of more than 100 mW are described with reference to the most important device parameters. The dependence of the lifetime of these high-power lasers on the ambient temperature and output power are also reported.

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Section: Transverse-mode Stabilizationmentioning

confidence: 99%

“…The half-angle θ ⊥ can be adjusted by designing the layer thickness of each layer appropriately, as described in detail elsewhere [11]. The measured COD levels under CW operation, averaged over several devices, are plotted against θ ⊥ in Fig.…”

Section: Cod Levelmentioning

confidence: 99%

High‐power GaN‐based semiconductor lasers

Ikeda¹,

Mizuno²,

Takeya³

et al. 2004

phys. stat. sol. (c)

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“…Our self aligned process for structuring ridge widths of 1.5 to 2.5 µm is described elsewhere [2]. We want to mention that we see advantages using absorbers on the GaN surface compared to earlier publications using absorbers on the top of the passivation layer [3]. Chip structuring is followed by scribing and cleaving of laser bars and facet coating using TiO 2 /SiO 2 .…”

Section: Methodsmentioning

confidence: 99%

Beam quality of blue InGaN laser for projection

Strauß

Eichler

Rumbolz

et al. 2008

Phys. Status Solidi (c)

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The blue light sources of choice for laser projection will be long wavelength nitride lasers because of their high wall plug efficiency and their small form factor compared to blue light sources using second harmonic generation. High quality of the far field is required for laser projection. However, optical confinement of GaN/AlGaN structures becomes increasingly difficult when wavelength shifts from 405 nm to the true blue spectrum. We will show excellent far fields by suppression of higher order laser modes and by improved waveguiding, respectively. We present simulations of laser modes as a function of ridge width. The slow axis far field is improved by absorber layers that guarantee in‐plane values of M2 < 1.5. Sufficient vertical confinement of the laser light by thick cladding layers is necessary to suppress laser modes guided within the substrate. We present 440 nm lasers for projection with threshold currents of 20 mA and slope efficiencies more than 0.8 W/A. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…[7][8][9][10] Another advantage of inserting an unintentionally doped GaN layer is the expansion of optical field distribution in the direction perpendicular to the junction plane, which is beneficial to reduce both optical power density in active region and the vertical divergence angle. 7,11 But during the device structure design and material epitaxial growth of InGaN LDs, the effect of layer thickness and background concentration of unintentionally doped GaN interlayer (IL) should be investigated in detail, which is going to be addressed in this article. The corresponding influence to the optical and electrical characteristics of InGaN LDs is theoretically simulated by the two-dimension simulator LASTIP.…”

Section: Introductionmentioning

confidence: 99%

The thickness design of unintentionally doped GaN interlayer matched with background doping level for InGaN-based laser diodes

et al. 2016

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In order to reduce the internal optical loss of InGaN laser diodes, an unintentionally doped GaN (u-GaN) interlayer is inserted between InGaN/GaN multiple quantum well active region and Al0.2Ga0.8N electron blocking layer. The thickness design of u-GaN interlayer matching up with background doping level for improving laser performance is studied. It is found that a suitably chosen u-GaN interlayer can well modulate the optical absorption loss and optical confinement factor. However, if the value of background doping concentration of u-GaN interlayer is too large, the output light power may decrease. The analysis of energy band diagram of a LD structure with 100 nm u-GaN interlayer shows that the width of n-side depletion region decreases when the background concentration increases, and may become even too small to cover whole MQW, resulting in a serious decrease of the output light power. It means that a suitable interlayer thickness design matching with the background doping level of u-GaN interlayer is significant for InGaN-based laser diodes.

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100-mW kink-free blue-violet laser diodes with low aspect ratio

Cited by 43 publications

References 13 publications

High‐power GaN‐based semiconductor lasers

High‐power GaN‐based semiconductor lasers

Beam quality of blue InGaN laser for projection

The thickness design of unintentionally doped GaN interlayer matched with background doping level for InGaN-based laser diodes

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