Fig. 3: Experimental demonstration of burst mode NRZ and PAM-4 transmission using discrete SOAs while switching.
From: Ultrafast optical circuit switching for data centers using integrated soliton microcombs
a A stream of multiple data packets showing data transmission along with sequential switching between the four comb channels. A single burst waveform sequence consists of header, payload, and guard zone containing 32, 1024, and 64 symbols respectively. b The signal after the frequency comb generator (FCG) and the optical switching unit (OSU) is amplified using a compact EDFA to compensate for losses of the 20-GHz Mach-Zehnder modulator (MZM). Then, it is filtered out using a wide-band optical bandpass filter (OBF) (~20 nm) to reject amplified spontaneous emission (ASE) noise from the SOAs and the EDFA. The data are encoded on the modulator using an arbitrary waveform generator (DAC). A fast photodiode (PD) is used to detect the signal. The electrical signal is amplified using a trans-impedance amplifier (TIA) and finally captured by an OSC. c) The bit error ratio (BER) of four different comb channels while switching between them, using different modulation formats non-return to zero (NRZ) and four-level pulse amplitude modulation (PAM-4). A performance below forward error correction (FEC) threshold is achieved for NRZ and PAM-4 for a received optical power of ~−12 dBm and ~−8 dBm, respectively. CH-34: 1552.524 nm, CH-40: 1557.363 nm, CH-44: 1560.606 nm, and CH-48: 1563.863 nm.
