Improvement of Current Injection Uniformity and Device Resistance  in Long-Wavelength Vertical-Cavity Surface-Emitting Laser  Using a Tunnel Junction

Sekiguchi, Satoshi; Miyamoto, Tomoyuki; Kimura, T.; Okazaki, Gen; Koyama, Fumio; Iga, Kenichi

doi:10.1143/jjap.39.3997

Cited by 11 publications

(4 citation statements)

References 12 publications

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“…An important criterion in determining whether implanted TJs can be used for current blocking is that the injected current must be uniform across the light-emitting aperture. 11 To evaluate this, we grew a VCSEL test structure on a ͑100͒ n-InP substrate. Above the active region consisting of seven quantum wells, a 0.35-m-thick p-InP cladding layer separates the TJ from the quantum wells and places it at a node of the standing optical field.…”

Section: ͑3͒mentioning

confidence: 99%

Helium ion-implanted InGaAsP tunnel junction current blocking layers

Wang

Forrest

2002

Applied Physics Letters

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We experimentally investigate and model He+-implanted InGaAsP tunnel junctions used for lateral current confinement in vertical-cavity surface-emitting lasers (VCSELs). Prior to implantation, a 56-μm-diameter tunnel junction exhibits a peak-to-valley ratio of 2.2 and a differential resistance of 27 Ω at −2 V. After implantation at a dose of 3.3×1013 cm−2, the current under reverse bias reduces by a factor of >107. Placing tunnel junctions close to the laser active region does not degrade the gain in the quantum wells. With He+-implanted tunnel junctions, mirrorless test VCSEL structures up to 50 μm diameter have uniform current distribution across the entire light-emitting apertures.

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Section: ͑3͒mentioning

confidence: 99%

Helium ion-implanted InGaAsP tunnel junction current blocking layers

Wang

Forrest

2002

Applied Physics Letters

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“…Moreover, a small specific resistance of 4 x 10-6 Qcm2 was achieved with the proposed type-II TJ of n-InGaAs/p-GaAsSb [5]. In addition to these reductions in resistance, for high-speed operation, differential gain is expected to increase because current injection uniformity is improved by electron injection with high mobility [6].…”

Section: Introductionmentioning

confidence: 96%

1.1-¿m-Range Tunnel Junction VCSELs with 27-GHz Relaxation Oscillation Frequency

Yashiki

Suzuki

Fukatsu

et al. 2007

OFC/NFOEC 2007 - 2007 Conference on Optical Fiber Communication and the National Fiber Optic Engineers Conference

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We have developed novel 1.1-ptm-range InGaAs VCSELs with buried type-II tunnel junctions for high-speed optical interconnections. A relaxation oscillation frequency of 27 GHz was achieved. Error-free 30-Gbps operations were demonstrated using directly modulated multimode VCSELs. C 2006 Optical Society of America OCIS codes: (250.7260) Vertical cavity surface emitting lasers; (140.5960) Semiconductor lasers IntroductionThe demands for higher data throughput and interconnect densities in high-end computing systems are growing quickly due to higher chip speeds, wider buses, and larger numbers of processors. However, the performance at electrical interconnections faces numerous challenges, such as power consumption, signal integrity, and electro-magnetic interference. Optical interconnects are expected to provide one of the major alternatives for upgrading interconnect performance. Vertical-cavity surface-emitting lasers (VCSELs) are promising light sources for optical interconnection because of their small size, which allows a high-density 2D array, low power consumption, and low costs.So far, we have developed strained InGaAs quantum wells (QWs) in VCSELs with an oxide-confined structure. The InGaAs QWs are desirable active layers for achieving the system requirements of high speed and reliability because they have a high differential gain and the indium suppresses dislocation motion [1]. We have achieved an error-free 25-Gbps operation with oxide-confined InGaAs-QW VCSELs [2]. However, the 3-dB bandwidth was 20 GHz. The relaxation oscillation frequency was saturated at 16 GHz by the self-heating effect. Here, the bandwidths are limited by the relaxation oscillation frequency. Therefore, we have proposed low-resistive VCSELs with buried type-II tunnel junctions (BTJ) to suppress the self-heating effect. By applying type-II tunnel junctions with extremely low specific resistance, we have reduced the chip resistance by half compared with conventional oxide-confined VCSELs [3].

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“…Therefore, the frequency of lasing mode could affected by the fluctuation and non-uniformity in both junction temperature and injected carrier density [9]. For the VCSELs, the reports also indicated the transverse mode structures depend on the drive current, [10] and the injection current from the periphery of the top contact aperture into the active region tends to cause current crowding and non-uniform current spreading [11][12][13][14]. Such non-uniform current spreading might lead to the kinks in L-I curve.…”

Section: Introductionmentioning

confidence: 99%

Improvement of kink characteristic of proton-implanted VCSEL with ITO overcoating

et al. 2004

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Proton implanted VCSEL has been demonstrated with good reliability and decent modulation speed up to 1.25 Gb/s. However, kinks in current vs light output (L-I) has been always an issue in the gain-guided proton implant VCSEL.The kink related jitter and noise performance made it difficult to meet 2.5 Gb/s (OC-48) requirement. The kinks in L-I curve can be attributed to non-uniform carrier distribution induced non-uniform gain distribution within emission area. In this paper, the effects of a Ti/ITO transparent over-coating on the proton-implanted AlGaAs/GaAs VCSELs (15um diameter aperture) are investigated. The kinks distribution in L-I characteristics from a 2 inch wafer is greatly improved compared to conventional process. These VCSELs exhibit nearly kink-free L-I output performance with threshold currents ~3 mA, and the slope efficiencies ~ 0.25 W/A. The near-field emission patterns suggest the Ti/ITO over-coating facilitates the current spreading and uniform carrier distribution of the top VCSEL contact thus enhancing the laser performance. Finally, we performed high speed modulation measurement. The eye diagram of proton-implanted VCSELs with Ti/ITO transparent over-coating operating at 2.125 Gb/s with 10mA bias and 9dB extinction ratio shows very clean eye with jitter less than 35 ps.

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Improvement of Current Injection Uniformity and Device Resistance in Long-Wavelength Vertical-Cavity Surface-Emitting Laser Using a Tunnel Junction

Cited by 11 publications

References 12 publications

Helium ion-implanted InGaAsP tunnel junction current blocking layers

Helium ion-implanted InGaAsP tunnel junction current blocking layers

1.1-¿m-Range Tunnel Junction VCSELs with 27-GHz Relaxation Oscillation Frequency

Improvement of kink characteristic of proton-implanted VCSEL with ITO overcoating

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