Growth and characterization of 850nm InGaAsP/InGaP strain-compensated VCSELs by MOCVD

Abstract

In this paper, we demonstrate the growth and characterization of 850nm oxide-confined VCSELs utilizing I n o , e G a a .~2 A s o~0 2 / l n a ,~G a a .~ strain-compensated SC-MQ Ws by MOCVD. The VCSEls show very low threshold current good temperature performance , and high modulation response up to 12.5Gb/s from 2JC to 85C. 850 nm Vertical Surface Emitting Lasers (VCSEL) have became a standard technology for application in local area networks (LANs) fiom 1.25 Gbls to 10Gb/s. In this paper, we demonstrate the high speed and high temperature operation of 850nm oxide-confmed VCSEL utilizing I n o .~~G a o .~~A s~.~P~.~f l~,~G a o .~P strain-compensated (SC-MQWs). The VCSEL wafer was grown on an Semi-insulating GaAs (100) substrate by MOCVD. The VCSELs have a 5 prn diameter emitting aperture defined by lateral oxidation. These VCSELs exhibit very low threshold currents -0.4 mA, and the slope efficiencies -0.5 mW/mA. The threshold current change with temperature is less than 0.2 mA and the slope efficiency drops less than -25% when the substrate temperature is raised from 25°C to 90°C. This is superior to the AIGaAdGaAs VCSEL with similar size. The resistance of our VCSELs is -95 Ohm and capacitance is -0.1 pF. Fig. 1 shows the smoothed small-singal modulation responses of a 5 p&VCSEL at different bias current levels. The modulation frequency is increased with increasing the bias current. With only 3mA (5mA) of bias current, the maximum 3dB modulation frequency response is measured -13 (14.5) GHz. 14.5 GHZ at 25 'C, is suitable for 12.5 Gb/s operation. As shown in Fig. 2(a) the room temperature eye diagram of our VCSEL biased at 4 mA with data up to 12.5 Gb/s and 6dB extinction ratio has a clear open eye pattern indicating good performance of the VCSELs. The rise time (Tr) is 28 ps and fall time (Tf) is 44 ps with jitter@-p)=20 ps. The VCSELs also show superior performance at high temperature. Fig. 2 (b) demonstrated the high speed performance of our VCSEL (biased at 5mA) with reasonable open eye-diagrams at 1 2 5 Gb/s and 6dB extinction ratio at 85°C. These VCSELs show very low threshold current good temperature performance , and high modulation response up to ,125 Gb/s from 25°C to 85°C .