Abstract
We propose an asynchronous gigabit-symmetric optical code division multiplexing access passive optical network (OCDMA-PON) in which optical network units (ONUs) are source-free. In the experiment, we demonstrate a duplex OCDMA system with a 50 km 10 Gbit/s/user 4-user DPSK-OCDMA downlink and a 50 km 10 Gbit/s/user 4-user OOK-OCDMA uplink and error-free duplex transmissions are achieved. Besides, we investigate an all-optical self-clocked time gate, which is used for the signal regeneration of decoded signals and ensures asynchronization in the up/downstream transmissions. Furthermore, we evaluate the power budget of the proposed duplex transmission.
Highlights
In the passive optical networks (PON), downstreams are broadcast to all end users, so it is necessary to encrypt the transmitted signals to guarantee information privacy and prevent eavesdropping
A fullasynchronous 10 Gigabit Ethernet (GbE) interface OCDMA prototype architecture was demonstrated in a field trial of duplex 10 Gbit/s/user 8-user differential phase-shift keying (DPSK)-OCDMA system over 100 km by using hybrid multi-port arrayed waveguide grating (AWG) and superstructured fiber Bragg grating (SSFBG) encoders/decoders [3]
A 2.5 Gbit/s on-off keying (OOK) upstream transmitter was proposed for remodulation in a wavelength division multiplexing (WDM)-PON by directly modulating an FP laser which was injection-locked by a 10 Gbit/s DPSK downstream signal
Summary
In the passive optical networks (PON), downstreams are broadcast to all end users, so it is necessary to encrypt the transmitted signals to guarantee information privacy and prevent eavesdropping. In [5, 6], OCDMA-PONs with source-free ONUs were proposed and realized in the incoherent and coherent OCDMA-PON by sending un-modulated and non-coded optical carrier from the central office to ONUs for upstream transmission. To simplify the structure of ONUs, several remodulation schemes have been proposed in the different PONs. A 2.5 Gbit/s on-off keying (OOK) upstream transmitter was proposed for remodulation in a wavelength division multiplexing (WDM)-PON by directly modulating an FP laser which was injection-locked by a 10 Gbit/s DPSK downstream signal. In [9], a centralized lightwave remodulation scheme which employed a 10 Gbit/s quadrature amplitude modulation (16-QAM) downstream and a remodulated 2.5 Gbit/s OOK upstream was proposed in an orthogonal frequency-division multiplexing (OFDM)-WDM-PON. We extend our recent work [10] to show a full picture of an asynchronous gigabit-symmetric DPSK-downstream and remodulated OOK-upstream OCDMA-PON.
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