Low-Cost All-Optical Up-Conversion of Digital Radio Signals Using a Directly Modulated 1550-nm Emitting VCSEL

The purpose of this letter is to demonstrate the extension of the modulation bandwidth of a single-mode vertical-cavity surface-emitting laser (VCSEL). The aim is to reach the radio-frequency range of wireless access networks such as ultrawide-band systems with low-cost solutions. In this letter, we have studied optical microwave mixing using nonlinear direct modulation of a VCSEL. First, the nonlinear behavior of the VCSEL near the threshold has been analyzed and explained based on frequency-mixing measurements made with continuous-wave signals. Then, we have experimentally demonstrated frequency up-conversion of a quaternary phase-shift-keying signal and a wireless local area network IEEE 802.11a signal.