In the last three decades, quantum information science and technology is one of the most exciting research fields. Among all the achievements, quantum secure communication technology is gradually started from experimental research to engineering application and expected to take the lead in achieving the commercial development. Towards the comprehensive popularization of the quantum secure communication system, a picosecond pulsed laser module has been designed and fabricated based on the gain-switching effect of the semiconductor laser and commercial electronic chips. The realized laser module has the following properties: operating wavelength at the low transmission loss window of fiber quantum channel, i.e., 1.5 μm; with a frequency fluctuation of less than 20 MHz; pulse time domain width of tens of picoseconds; no fixed phase correlation between any two pulses. Moreover, these properties are verified and discussed based on the requirement of weak coherent single photon source for quantum secure communication application.