High-Power AlGaInN Laser Diodes with High Kink Level and Low Relative Intensity Noise

Tojyo, T.; Uchida, Shiro; Mizuno, Takashi; Asano, T.; Takeya, M.; Hino, T.; Kijima, Satoru; Goto, Shu; Yabuki, Yoshifumi; Ikeda, Masao

doi:10.1143/jjap.41.1829

Cited by 39 publications

(20 citation statements)

References 4 publications

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“…In agreement with literature data, we found that for single mode operation the ridge width has to be smaller than 2 m. 5,6 In conclusion, we have presented time-resolved emission spectra and far-field distributions along with theoretical computations which show that local self-heating of InGaN-based violet-blue diode lasers together with carrier diffusion effects can result in lateral mode switching and beam steering of the far field on a microsecond time scale. This unwanted behavior can be avoided if the ridge width is reduced to 1.5 m. …”

supporting

confidence: 89%

Microsecond time scale lateral-mode dynamics in a narrow stripe InGaN laser

Eichler¹,

Hofstetter²,

Chow³

et al. 2004

Applied Physics Letters

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Time-resolved measurements of the spectrum and the far field of InGaN-based laser diodes show lateral-mode changes and gradual tilting of the far field on a microsecond time scale. Numerical simulations based on a microscopic theory are in good agreement with the measurements. The observed effects are attributed to lateral carrier diffusion in combination with thermal lensing.For violet-blue diode lasers, there exist several important applications, such as optical storage and laser printing, requiring lateral mode stability. While the design of singlemode lasers is an ongoing problem, the underlying physical mechanisms leading to stable fundamental-lateral mode operation in conventional semiconductor lasers is, in principle, well understood. However, this understanding may not apply to the wide-band-gap group-III nitride ͑III-N͒ material system because of its drastically different physical properties. The investigated laser diodes were fabricated by OSRAM Opto Semiconductors. They were grown on a SiC substrate without ELO techniques by metalorganic chemical vapor deposition and consist of a 560 nm thick AlGaN:Si cladding, followed by a 120 nm GaN:Si lower waveguide layer, three 2 nm In 0.1 Ga 0.9 N/GaN quantum wells with GaN:Si barriers, an Al 0.2 Ga 0.8 N electron blocking layer, a 100 nm thick GaN:Mg upper waveguide layer, and a 400 nm thick AlGaN:Mg upper cladding layer. Contacts are deposited on a p-GaN cap layer on top of the ridge and on the n-SiC backside. The cleaved facets are coated with high reflectivity coating (Rϳ98%/70%).2 The devices are operated in junction side up configuration, which is possible due to the SiC substrate. Since we use short pulses in the microsecond range, the back contact of the device does not see a temperature increase during the pulse, as shown in Ref. 3. After each pulse, the laser has enough time to cool down again due to the very low duty cycle. Thus, the kind of mounting the device onto the heatsink has only negligible influence on the effects described in this letter.For measurements of the time-resolved optical spectrum, the light of the temperature stabilized laser diode is collimated and then focused on the entrance slit of a grating monochromator. At the output slit, the light of the actually selected wavelength is collected by a fast photomultiplier tube. Thus, for this particular wavelength the intensity distribution versus time can be observed on an oscilloscope connected to the photomultiplier tube. Scanning the selected wavelength of the monochromator over the range of the emission spectrum of the laser diode yields therefore a threedimensional graphics with time and wavelength as the x and y axis, respectively, and optical intensity as the z axis ͑color encoded͒. This plot, which is shown in Fig. 1 ͑top͒, allows to observe the evolution of the laser spectrum during a current pulse. The corresponding time-resolved far field is measured in the same manner. The only difference to the previous measurement is that the monochromator is now replaced by a step motor c...

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supporting

confidence: 89%

Microsecond time scale lateral-mode dynamics in a narrow stripe InGaN laser

Eichler¹,

Hofstetter²,

Chow³

et al. 2004

Applied Physics Letters

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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%

“…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.…”

mentioning

confidence: 99%

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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“…The reliability of AlGaInN-based LDs has been dramatically improved by the introduction of the epitaxial lateral overgrowth (ELO) technique [2][3][4][5][6][7] for the basal layer of LDs. The estimated lifetime of present devices exceeds 10,000 h under 30 mW cw operation at 60 °C [8,9] However, in spite of these developments, the degradation mechanism of these devices has yet to be fully understood. In this paper, the results of degradation experiments for AlGaInN-based laser diodes conducted for the purpose of obtaining evidence on which to construct a possible model of the degradation mechanism are reported.…”

mentioning

confidence: 99%

Degradation in AlGaInN lasers

Takeya¹,

Mizuno²,

Sasaki³

et al. 2003

phys. stat. sol. (c)

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Degradation experiments for AlGaInN-based laser diodes were conducted for the purpose of constructing a possible model of the degradation mechanism. Lasers in this experiment were aged under 30 mW continuous-wave operation at 60 °C, and the lifetime was defined as the time at which the operating current increased by 20%. The lifetime was found to be dependent on the dislocation density of the basal ELOGaN layer, with the degradation rate being almost proportional to the square root of aging time. A model of degradation in which degradation is governed by a diffusion process is proposed based on these results. Although the model describes the experimental findings well, further investigation is considered necessary before the degradation mechanism in AlGaInN lasers can be fully understood.

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High-Power AlGaInN Laser Diodes with High Kink Level and Low Relative Intensity Noise

Cited by 39 publications

References 4 publications

Microsecond time scale lateral-mode dynamics in a narrow stripe InGaN laser

Microsecond time scale lateral-mode dynamics in a narrow stripe InGaN laser

High‐power GaN‐based semiconductor lasers

Degradation in AlGaInN lasers

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