Analog characterization of low-voltage MQW traveling-wave electroabsorption modulators

Abstract—In this paper, high-speed traveling-wave elec-troabsorption modulators (TW-EAMs) with strain-compensated InGaAsP multiple quantum wells as the absorption region for analog optical links have been developed. A record-high slope efficiency of 4/V, which is equivalent to a Mach–Zehnder modu-lator with a of 0.37 V and a high extinction ratio of 30 dB/V have been measured. A detailed study of the nonlinearity and the spurious-free dynamic range (SFDR) is presented. By optimizing the bias voltage and the input optical power, the SFDR can be improved by 10–30 dB. After minimizing the third-order distortion, an SFDR as high as 128 dB Hz4 5 is achieved at 10 GHz. A simple link measurement was made using this EAM and an erbium-doped fiber amplifier and a 50-terminated photodetector. At 10 GHz, a link gain of 1 dB is achieved at a detected photocurrent of 7.6 mA with higher gains at lower frequencies. The dependence of link gains on bias voltage, input optical, and radio frequency powers are investigated in detail. Index Terms—Analog optical link, electroabsorption modulator (EAM), link gain, multiple quantum wells (MQWs), spurious-free dynamic range (SFDR), traveling wave (TW). I