A time domain photonic arbitrary waveform generator (PAWG) scheme based on multi-wavelength optical differential quadrature phase shift keying modulation in combination with differential detection is proposed and experimentally demonstrated. The time domain method shows advantages of large time-bandwidth product, good flexibility, fast waveform refreshing rate, and high waveform quality over the frequency domain method. In contrast with other proposed time domain PAWGs or photonic digital-to-analog converters, our PAWG proposal shows a greater dynamic range and a larger noise margin due to its bipolar output, and possesses good scalabilities both in resolution and sampling rate. Assisted with the integration technology, this PAWG presents a good prospect for broad range practical applications in future.