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We have demonstrated multi-wavelength VCSEL array operating at 1060nm with dielectric phase tuning layers. Uniform threshold currents of approximately 0.35mA were successfully realized over 16 channels (10nm wavelength span) by only four-step lithography and etching.

It is important to know distance characteristics of electric field pattern to measure radiation patterns for car mounted antennas. In this paper, distance characteristics of electric field pattern for an antenna mounted on a car in the UHF band are investigated by the electromagnetic simulation for the first time. As a result, it is shown that distance characteristics of electric field pattern are affected by polarization, frequency, antenna positions, and origin positions to define the distance.

This paper reviews research and development of 1060nm VCSELs at Furukawa Electric. We pursue the simultaneous realization of three strong demands for low power consumption, high reliability, and high speed. For this purpose, we have chosen compressively strained InGaAs/GaAs active layers emitting in a 1060 nm wavelength range because of their advantages of lower threshold voltage, smaller defect propagation velocity, and larger material differential gain, compared to those of GaAs/AlGaAs active layers widely used in 850 nm VCSELs. Oxide-confined and double intracavity structures provide low and stable electrical resistance as well as low optical loss. The developed VCSELs exhibited low threshold currents of 0.31 mA at 25 °C and 0.56 mA at 90 °C, together with highly uniform slope efficiency distributions throughout a wafer. We also demonstrated 10 Gbps error free transmission at a very low bias current of 1.4 mA, yielding low power dissipation operation of 0.14 mW/Gbps. Clear eye openings up to 20 Gbps were confirmed at a low bias current of 3mA. A series of endurance tests and accelerated aging tests on nearly 5000 VCSELs have proved Telcordia qualified high reliability and a very low failure rate of 30 FIT/channel at an operating temperature of 40 °C and a bias current of 6mA, with a 90% confidential level.

Furukawa's 1060nm VCSELs with double-intra-cavity structure and Al-free InGaAs/GaAs QWs enable us to realize low power consumption, high speed operation and high reliability simultaneously. The power dissipation was as low as 140fJ/bit. Clear eye opening up to 20Gbps was achieved. Random failure rate and wear-out lifetime were evaluated as 30FIT/channel and 300 years. For higher speed operation, thickness of oxidation layer was increased for lower parasitic capacitance of device. Preliminary reliability test was performed on those devices. In high speed operation faster than 10Gbps, conventional lifetime definition as 2dB down of output power is not sufficient due to smaller margin of modulation characteristics. We suggest threshold current as a barometer for degradation of modulation characteristics. The threshold currents of our VCSELs degrade small enough during accelerated aging test. We also observed no remarkable change in 25Gbps eye diagram after aging test. The definition of life time for high speed VCSEL is discussed from the change in threshold current and so on in addition to the conventional power degradation during aging. It is experimentally verified that our VCSELs are promising candidate for highly reliable light source including long term stable high speed operation.

High reliability, low power consumption and high speed laser diodes are required for optical interconnect. We developed 1060nm VCSELs with InGaAs/GaAs strained quantum wells, oxide-confined and double intra-cavity structures for that purpose. As for the power consumption, low power dissipation of 0.14 mW/Gbps at 10 Gbps operation has been achieved. Clear eye openings up to 20 Gbps were confirmed at a low bias current of 5 mA. In the reliability test, accelerated aging tests were performed up to 5,000 hours at 6 mA in three different temperatures, 70 oC, 90 oC and 120 oC. The total number of the VCSELs was 4,898 pcs (approximately 5,000). No failure was observed. Under the normal operating condition of 40 oC and 6 mA, the total device-hours was 7.75×107 hours assuming Ea = 0.35 eV according to Telcordia GR-468-CORE. The random failure rate of 30 FIT with the confidence level (C.L.) of 90 % and 12 FIT with the C.L. of 60 % were estimated. To estimate the wear-out lifetime and the number of FITs, high stressed aging tests with 170 oC and 6 mA were performed. With the acceleration factor of Ea = 0.7 eV in the wear-out failure, the median lifetime was 3,000 hours which was equivalent to 300 years in 40 oC ambient. The FIT numbers due to the wear-out were estimated as 0.3 FIT for 10 years. Compared with the random failure rate of 30 FIT, the wear-out failure rates are considered to be negligible. In the extremely long term aging test with 90 oC and 6 mA, no wear-out trend has been observed in both threshold current and optical power up to 20,000 hours operation. These results indicate that 1060 nm VCSEL is promising light source used in optical interconnect for high performance computers and data centers.

The demand for the on board intra-chip optical interconnection as the "Green interconnect" have been growing so rapidly in order to catch up the speed of the performance development of high performance computing systems. In this report, our continuous study results expanding to intra-chip application in terms with power consumption and reliability are shown for the "Green" 1060nm VCSEL arrays developed by Furukawa Electric 1 . As the basic performance level, the clear eye opening up to 20Gbps was achieved with low power dissipation level of 160fJ/bit with voltage swing level of 130mVpp. This value would be considered as the same level of the 140fJ/bit in 10Gbps operation with 75mVpp. In the reliability test, our large scale FIT rate test had been reached up to 7.8E7 device hours and the estimated FIT rate of 30FIT/ch was obtained from no failure sample and confidence level of 90%. Our wear-out study was performed with high stress test of 170°C ambient temperature and estimated failure rate for 10years service time was 0.3FIT/ch for this mode. Our 1060nm VCSEL with low power consumption level of 140fJ/bit and high reliability of 30FIT/ch would be projected to a light source for intra-chip application.

1060nm VCSELs with InGaAs/GaAs strained quantum wells have been reviewed in terms of power consumption and reliability. Clear eye opening was confirmed at 10Gbps with bias current of as low as 1.4mA.

Extremely low power dissipation of 0.14 mW/Gbps at 10 Gbps operation with as small as 75 mV p-p of modulation amplitude has been achieved in carefully designed InGaAs/GaAs-MQW 1060 nm VCSELs employed double intra-cavity structure.

VCSEL performance will be reviewed. A careful design of cavity structure, as well as precise control in the epitaxial growth enables us to achieve a record power conversion efficiency of 62% in the 1060nm VCSELs.

The optical absorption coefficient (α) for carbon-doped GaAs epitaxial layer by CBr 4 with doping range from 1018 to 1020 cm−3 was measured for the first time. Obtained α GaAs:C was 2-times larger than α GaAs:Zn at 1300nm.

High efficiency VCSELs will be reviewed in terms of power conversion efficiency. Other lasing parameters will be also discussed.

VCSELs will be reviewed in terms of power conversion efficiency in this talk. In addition, high speed VCSEL and its transmitter modules for parallel optical interconnection will be presented.