Flat optical frequency comb generation employing cascaded dual-drive Mach-Zehnder modulators
Binoy Das, Khaleda Mallick, Paulomi Mandal, Bubai Dutta, Chiranjib Barman, Ardhendu Sekhar Patra
Abstract
The generation of flat optical frequency comb lines (OFCL) of 10 GHz frequency spacing is proposed and demonstrated theoretically employing Dual-Drive Mach Zehnder modulators (DD-MZMs). A theoretical analysis is carried out for ultra flat spectra due to single stage and cascading of DD-MZMs, which is confirmed by simulative results. Employing single DD-MZM, 19 OFCL with flatness 0 dB and 39 OFCL with flatness ≤ 1 dB have been generated at 11.16 Vπ−11.66 Vπ modulation voltages. 37 comb lines are obtained with 0 dB flatness and 49 OFCL with flatness ≤ 0.5 dB using two cascaded dual drive MZMs at 5.61 Vπ–6.11 Vπ–5.61 Vπ, 6.11 Vπ modulation voltages. Combining four DD-MZMs, 34 & 54 OFCL with flatness 0 dB and ≤ 0.5 dB is generated at modulation voltages 2.78 Vπ and 3.33 Vπ. Large numbers of OFCL with very high flatness are achieved by applying low RF voltage.