We have demonstrated high density, 2D (4x12) VCSEL arrays operating at an aggregate data rate of over 480Gb/s in an aerial density of 1400x3750 μm<sup>2</sup>, or 9.14 Tbs/cm<sup>2</sup>. These flip-chip, bottom-emitting 990nm VCSELs have low drive voltage, low electrical parasitics, improved thermal impedance and 2D scalability over their wire-bonded top emitting counterparts. Excellent high speed performance was obtained through the use of 1) compressively strained InGaAs MQW active region 2) low parasitic capacitance oxide-confined VCSEL structures and 3) low series resistance, high index contrast AlGaAs/GaAs mirrors. 10Gb/s operation was obtained with low operating current density of ~6kA/cm<sup>2</sup> at 70C. Our best results to date have achieved data rates greater than 12.5Gb/s @70C at a current density less than 10kA/cm<sup>2</sup>. The device results show good agreement with theoretically calculated/simulated values.
This work was partially supported by DARPA under contract MDA972-03-3-0004.
We report results for broad area edge emitting lasers having AlInGaAs active regions that exhibit low thresholds, high T<sub>0</sub> and T<sub>1</sub> and high efficiencies. The lasers were grown on InP substrates using MOCVD. This paper analyzes the effects of doping, epilayer design, wavelength dependence and number of QWs on device performance. Our results show that the concentration and offset of zinc doping in the p-cladding layer plays a major role in carrier confinement and hence high temperature performance. The difference in surface mobility of Al adatoms (as compared to In or Ga) poses some challenges in the growth of AlInGaAs.
We demonstrate novel electrically pumped 1300 nm and 1550 nm VCSELs with two InP/air-gap DBRs. The active
regions comprise conventional InGaAsP multiple quantum wells. A tunnel junction is placed between the active region
and top DBR to convert electrons into holes, thus minimizing the use of p-type material in the structure to reduce the
free-carrier loss and achieve current confinement. The whole structure was grown in a single growth run by low
pressure MOCVD. For both 1300 and 1550 nm emission wavelengths, air-gap DBR VCSELs exhibit roomtemperature,
CW threshold current density as low as 1.1 kA/cm<sup>2</sup>, differential quantum efficiency greater than 30%, and
CW operation up to 85°C. The single-mode output power was 1.6 mW from a 1300 nm VCSEL with a 6.3 μm
aperture; and 1.1 mW from a 1550 nm VCSEL with a 5.7 μm aperture under room temperature CW operation