850nm gain-switched pulse laser and its application in photon counting OTDR

In this study, we propose and experimentally demonstrate a picosecond pulse laser at 850 nm. To generate picosecond laser pulse, we operate a vertical cavity surface emitting laser under a gain-switched pulsed mode, which is realized by driving it with our home-made drive circuit based on field programmable gate array and radio frequency devices. The obtained laser pulses are with the pulse width of less than 675 ps, and with repetition rate from single shot to megahertz. On the other hand, based on our gain-switched pulsed laser, we design and realize a cost-effective optical time domain reflectometry prototype equipment with photon counting technology for monitoring the healthy condition of aeronautical fiber. Our prototype equipment achieves a spatial resolution of less than 9 cm, and a dynamic range of around 18 dB above the noise floor. Such prototype equipment has already been employed to monitor an optical cable with 32 fiber channels on plane.