Frequency-Doubling Photonic Vector Millimeter-Wave Signal Generation From One DML

We propose a novel and simple scheme for high-frequency photonic vector millimeter-wave (mm-wave) signal generation based on photonic frequency doubling enabled by a single directly modulated laser (DML), precoding, and analog frequency upconversion. The introduction of a DML avoids the need for an external optical modulator and, thus, simplifies the architecture and reduces the cost. The adoption of analog frequency upconversion effectively overcomes the bandwidth limitation of the current commercially available digital-to-analog converters (DACs) and, thus, increases the attained carrier frequency of the generated vector mm-wave signal. Based on our proposed scheme, we experimentally demonstrate the generation of a 40-GHz quadrature phase-shift keying (QPSK)-modulated vector mm-wave signal. The generated 40-GHz QPSK-modulated vector mm-wave signal can be delivered over a 0.5-m wireless distance with up to a 4-GBd rate and a bit error ratio (BER) less than the hard-decision forward-error-correction (HD-FEC) threshold of 3.8 × 10^-3.