Advanced lithium niobate optical modulators for optical communication applications

Abstract

Centralized-light-source wavelength division multiplexing passive optical network (WDM-PON) has been intensively studied in recent years. Several re-modulation schemes have been proposed and demonstrated in laboratory but each with several disadvantages. To achieve a colorless optical network unit (ONU) and overcome the disadvantages of previous schemes, a novel scheme with downstream polarization shift keying (PolSK) and upstream on-off keying (OOK) is proposed and demonstrated. PolSK is generated by a polarization modulator (PolM) which is commercialized recently. The PolSK coded by PolM appears to be more immune to polarization fluctuation of input polarization state and is free from frequency chirp, compared with previous PolSK generation by phase modulator (PM). With 20km downstream and upstream transmission, the signal is maintained a low bit error rate (BER) which indicates the proposed scheme is a potential candidate for next generation wavelength-reuse WDM-PON.