Chang-Joon Chae

Fixed Mobile Convergence Architectures for Broadband Access: Integration of EPON and WiMAX [Topics in Optical Communications]

EPON and WiMAX are two promising broadband access technologies for new-generation wired and wireless access. Their complementary features motivate interest in using EPON as a backhaul to connect multiple dispersed WiMAX base stations. In this article we propose four broadband access architectures to integrate EPON and WiMAX technologies. The integrated architectures can take advantage of the bandwidth benefit of fiber communications, and the mobile and non-line-of-sight features of wireless communications. Based on these integrated architectures, we elaborate on related control and operation issues to address the benefits gained by this integration. Integration of EPON and WiMAX enables fixed mobile convergence, and is expected to significantly reduce overall design and operational costs for new-generation broadband access networks.

High-speed WDM-PON using CW injection-locked Fabry-Pérot laser diodes

We propose a new WDM-PON architecture using Fabry-Pérot laser diodes (FP-LDs) that are injection-locked by continuous wave (CW) seed light. The modulation characteristics of the CW light injection-locked FP-LD are first investigated. Both uplink and downlink transmissions at 10 Gb/s are experimentally demonstrated using the proposed CW injection-locked FP-LDs. It is shown that up to 16 laser cavity modes can be selectively injection-locked with side mode suppression ratio larger than 30dB. The effects of the location of FP-LD cavity modes, transmission distance, and injection wavelength detuning on the overall transmission performance are investigated. The possibility of eliminating polarization dependence of the proposed CW injection scheme is also experimentally demonstrated by properly configuring a depolarizer. The deployment cost for the proposed WDM PON is potentially low from the fact that the CW laser sources located at the central office can be shared by many WDM-PONs and low-cost FP-LDs are used as light sources for data rates as high as 10 Gb/s.

Optical CSMA/CD media access scheme for Ethernet over passive optical network

In this letter, we propose and demonstrate a novel implementation of optical carrier-sense multiple access with collision detection to efficiently transport Ethernet frames over a star coupler (SC) based passive optical network. We introduce a redirection mechanism at the SC to achieve high channel efficiency.

Selective broadcasting of digital video signals over a WDM passive optical network

Using a common optical modulator for baseband modulation and subcarrier multiplexing, and by controlling the individual transmitter laser bias at the central office, selective broadcasting of a 155-Mb/s digital video signal over a WDM passive optical network is demonstrated with a 1-Gb/s downstream data signal being simultaneously transmitted. A power penalty <0.5dB is observed for both signals at 10/sup -9/ bit-error rate.

CSMA/CD-based ethernet passive optical network with optical internetworking capability among users

The integration of data services with bandwidth-consuming broadcast services in the access network segment is anticipated in the foreseeable future. The Ethernet passive optical network (EPON) is actively being developed to meet the ever-increasing bandwidth demand in a cost-effective and future-proof manner, with internetworking among connected users to emulate shared local area network (LAN) capability being an important feature. In this work, we propose a novel EPON that utilizes an N/spl times/N star coupler to facilitate shared LAN capability in addition to conventional access services. It features high upstream channel utilization with reasonable delay, relieves the processing burden at the central office, and offers significant savings in the downstream bandwidth for data transmission.

Bandwidth-efficient PON system for broad-band access and local customer Internetworking

We present a new passive optical network (PON) architecture for broad-band access and local customer networking. It provides high bandwidth efficiency for delivering both PON and customer internetworking services. The architecture separates the local optical network from the PON system, thereby enhancing security, flexibility, and allowing the use of any media access control protocol. The local customer internetworking feature is demonstrated with insignificant penalty to the overall PON system performance.

Compact and reconfigurable silicon nitride time-bin entanglement circuit

Photonic-chip-based time-bin entanglement has attracted significant attention because of its potential for quantum communication and computation. Useful time-bin entanglement systems must be able to generate, manipulate, and analyze entangled photons on a photonic chip for stable, scalable, and reconfigurable operation. Here we report the first time-bin entanglement photonic chip that integrates pump time-bin preparation, wavelength demultiplexing, and entanglement analysis. A two-photon interference fringe with 88.4% visibility is measured (without subtracting any noise), indicating the high performance of the chip. Our approach, based on a silicon nitride photonic circuit, which combines low loss and tight integration features, paves the way for scalable real-world quantum information processors.

Active temporal multiplexing of indistinguishable heralded single photons.

It is a fundamental challenge in quantum optics to deterministically generate indistinguishable single photons through non-deterministic nonlinear optical processes, due to the intrinsic coupling of single- and multi-photon-generation probabilities in these processes. Actively multiplexing photons generated in many temporal modes can decouple these probabilities, but key issues are to minimize resource requirements to allow scalability, and to ensure indistinguishability of the generated photons. Here we demonstrate the multiplexing of photons from four temporal modes solely using fibre-integrated optics and off-the-shelf electronic components. We show a 100% enhancement to the single-photon output probability without introducing additional multi-photon noise. Photon indistinguishability is confirmed by a fourfold Hong–Ou–Mandel quantum interference with a 91±16% visibility after subtracting multi-photon noise due to high pump power. Our demonstration paves the way for scalable multiplexing of many non-deterministic photon sources to a single near-deterministic source, which will be of benefit to future quantum photonic technologies.

EDFA transient control based on envelope detection for optical burst switched networks

We propose and demonstrate a simple technique to control rapid erbium-doped fiber amplifier (EDFA) transients in optical burst switched networks. We demonstrate a 6-dB transient reduction in a 10-Gb/s 80-km-long wavelength-division-multiplexing system with three EDFAs. We show through simulation that the technique can be used at the first EDFA in links of as many as ten EDFAs to control transients to within 2 dB.

Ethernet PON or WDM PON: A Comparison of Cost and Reliability

We report a comparison of cost and reliability of two optical broadband access technologies namely Ethernet passive optical network (EPON) and WDM PON (WPON), taking into account two protection schemes and two deployment scenarios. We derive simple network models and a figure of merit for network cost and reliability evaluation. We find that with a take rate ges 60%, WPON technology provides the lowest cost per subscriber per Mbit/s. Moreover, with full protection, the PON architectures achieve a low mean down time of 27 min/year, which is smaller than that of the copper-based access network.