Transmission of 40-Gb/s QPSK upstream signal in RSOA-based coherent WDM PON using offset PDM technique

Abstract

We demonstrate the 40-Gb/s upstream transmission in the 60-km reach wavelength-division-multiplexed passive optical network (WDM PON) implemented by using directly modulated reflective semiconductor optical amplifiers (RSOAs) and self-homodyne receivers. It is difficult to operate the RSOA at 40 Gb/s due to its limited modulation bandwidth. To overcome this problem and generate 40-Gb/s upstream signal, we utilize the quadrature phase-shift-keying (QPSK) format and the offset polarization-division-multiplexing (PDM) technique. For this purpose, we install two RSOAs at each ONU and provide the seed light for these RSOAs by polarization-multiplexing the outputs of two lasers with a small frequency offset (20 GHz). This frequency offset is used to separate the polarization-multiplexed seed light by using a simple delay-line interferometer (DLI), instead of the polarization-beam splitter and polarization controller, at the ONU. The separated seed light is modulated by each RSOA at 20 Gb/s in the QPSK format, and then combined again by the DLI before sent back to the central office (CO). The results show that this WDM PON can support the transmission of 40-Gb/s channels spaced at 50 GHz over 60 km without using any remote optical amplifiers.

Integrated Fiber-FSO WDM Access System with Fiber Fault Protection

“…The traffic rates of these TDM-PONs were from 1 to 40 Gb/s for broadcasting and power-sharing downstream data due to the PTMP operation. To achieve higher data capacity and network security, the PTP-based WDM-PON systems with the traffic rate from 1 to 60 Gb/s and even to 100 Gb/s have been studied and demonstrated extensively [12][13][14][15]. Due to the high amount of data transmitted in WDM system, the stability and reliability of the fiber access network is extremely important [16].…”

Multiple Access Noise Compensation in CO-OFDMA-PON Uplink Transmission Using Digital Phase Conjugated-Pilot Tones

“…To deal with multiple SOPLs, [11] explored optical intensity reception in both polarization axes; however, the modulation format was restricted to intensity modulation. Further, in [12], single pilot-tone (PT)-based independent SOP tracking was proposed without any optical handling of the SOP such as [15], [16]. This technique enabled simpler and faster compensation compared with other complex sample-by-sample tracking methods [17], [18] and transparent for modulation format, whereas tracking accuracy could be degraded in more severe SOPLs owing to the insufficient estimator samples.…”

Upstream WDM-PON transmission scheme based on PDM-OOK modulation and digital coherent detection with dual-modulus algorithm

“…With the rapid development of Internet and proliferation of multimedia-based services, the bandwidth demand of end-users increases constantly, and a high-speed passive optical network (PON) supporting at least 40-Gb/s service for certain subscribers will be in demand in the near future [1,2]. Owing to advantages including large bandwidth, protocol transparency and scalability to support multiple subscribers, wavelength-divisionmultiplexing (WDM)-PON is deemed promising to cope with the capacity requirement [3].…”

“…With massive production and advanced photonic integration techniques, coherent or selfcoherent detection is becoming an attractive choice for upstream WDM-PON [2,7], which can provide higher power budget by improving receiver sensitivity. In this paper, we propose an upstream WDM-PON scheme based on PDM-OOK modulation at the ONU and digital coherent or self-coherent detection at the optical line terminal (OLT).…”