High-speed VCSEL of modulation bandwidth over 7.0 GHz and its application to 100 m PCF datalink

High-speed vertical cavity surface emitting laser (VCSEL) with 6 x 6 mu m active area is fabricated by reducing its pad area in order to reduce its parasitic capacitance. The fabricated VCSEL shows the 3 dB bandwidth of over 7 GHz and average threshold current of 0.7 mA. This is the highest 3 dB modulation bandwidth ever reported for the plan type bottom emitted laser with pad. The maximum intrinsic bandwidth as estimated from k-factor is found to be over 20 GHz, which is less than three times than the observed bandwidth, The thermal characteristics are also found to be almost unchanged due to the reducing of its pad size. It also showed open eye pattern for 3 GHz nonreturn to zero (NRZ) pseudorandom signal after transmission through 100 m large core plastic clad fiber (PCF), which could be used in short and medium distance optical links.