Demonstration of 512-TR-PPM Fiber Optical Transmission Link

In this paper, we demonstrate a data transfer over a 20km long single-mode fiber (SMF) optical communication link using a transmitted-reference pulse position modulated (TR-PPM) signals with a pulse duration of 50 ps. Employment of position widths (time bins) of 50, 100, and 200 ps with 512 positions per one symbol allows achieving a transmission rate of up to 59.5 Mbps. Implementation of a robust PPM communication with a very low duty cycle over the C-band fiber optical links, where the typical signal attenuation for standard SMF fiber is around 0.2 dB/km at 1550 nm wavelength, paves the way to long-reach high energy-efficiency data transmission links. After photodetection by high-speed PIN photodiode, precisely detecting a high number of pulse positions with 50 ps accuracy is challenging. Therefore, we demonstrate TR-PPM signal demodulation using a high-accuracy event timer A033-ET. To enable the operation of this event timer, PPM pulses at the input of this timer are expanded to at least 700 ps using our developed pulse duration expansion module, which includes an in-house manufactured electrical low-pass filter (LPF) and other supporting radio frequency components.