This paper reviews advanced optical burst switching (OBS) and optical packet switching (OPS) technologies and discusses their roles in the future photonic Internet. Discussions include optoelectronic and optical systems technologies as well as systems integration into viable network elements (OBS and OPS routers). Optical label switching (OLS) offers a unified multiple-service platform with effective and agile utilization of the available optical bandwidth in support of voice, data, and multimedia services on the Internet Protocol. In particular, OLS routers with wavelength routing switching fabrics and parallel optical labeling allow forwarding of asynchronously arriving variable-length packets, bursts, and circuits. By exploiting contention resolution in wavelength, time, and space domains, the OLS routers can achieve high throughput without resorting to a store-and-forward method associated with large buffer requirements. Testbed demonstrations employing OLS edge routers show high-performance networking in support of multimedia and data communications applications over the photonic Internet with optical packets and bursts switched directly at the optical layer

Optical Packet and Burst Switching Technologies for the Future Photonic Internet

Dynamic optimization: The calculus of variations and optimal control in economics and management: Morton I. KAMIEN and Nancy L. SCHWARTZ Volume 4 in: Dynamic Economics: Theory and Applications, North-Holland, New York, 1981, xi + 331 pages, Dfl.90.00

This paper introduces a new measure, the Trade Restrictiveness Index, which measures the restrictiveness of a system of trade protection. The index is a general equilibrium application of the distance function and answers the question: "What uniform set of trade restrictions is equivalent (in welfare terms) to the initial protective structure?" The index is applicable to both tariffs and quotas and allows international and intertemporal comparisons. The index is operational and we provide an empirical example to illustrate its applicability and to show its superiority to commonly used measures.

/pdf/a-new-approach-to-evaluating-trade-policy-4pyp2s6kaa.pdf

A new approach to evaluating trade policy

Most theoretical models of urban land use concentrate on residential density. This paper takes up another important use of urban land, for roads, or, more generally, for transportation. The paper analyzes, in the simplest possible setting, the optimal allocation of a given urban land area between the generation of traffic and the carrying of traffic. It shows that, except in a limiting case, the proportion of land allocated to transportation is a decreasing, concave function of distance from the center of the city. The competitive rent profile generated by land-use pattern is then analyzed, on the assumptions that there are no congestion tolls for road use, and that commodities are sold at uniform delivered price with sellers absorbing transport cost. On these assumptions, the paper shows that the market value of land may be a very poor guide to land-use decisions, and would lead to overallocation of land to transportation, especially near the center. The model used is one-dimensional.

Land use in a long narrow city

A statistical yield analysis is presented for gain- and index-coupled distributed feedback (DFB) laser structures, allowing a comparison of their single longitudinal mode (SLM) yield capabilities. For the yield calculations, the threshold gain difference and the longitudinal spatial hole burning (SHB) are taken into account. By comparing the experimental and theoretical yield of index-coupled DFB lasers, the significance of SHB for correct yield predictions is illustrated. For the purpose of comparison, yield calculations for various lambda /4-shifted DFB lasers (with low facet reflectivities) are presented. The most emphasis, however, is on partly gain-coupled DFB lasers. Estimations of practical gain coupling coefficient values for gain and for loss gratings are discussed. >

Gain-coupled DFB lasers versus index-coupled and phase shifted DFB lasers: a comparison based on spatial hole burning corrected yield

A novel all-optical modulation-format conversion from nonreturn-to-zero on-off keying (NRZ-OOK) to return-to-zero binary phase-shift keying (RZ-BPSK) is proposed. A Mach-Zehnder interferometric (MZI) wavelength converter consisting of integrated semiconductor optical amplifiers (SOAs) is utilized to implement the proposed format conversion. Error-free operation at a bit rate of 10.7 Gb/s is experimentally demonstrated in order to show the feasibility of the proposed scheme. The received sensitivity of the converted signal is improved by 2.9 dB compared with a back-to-back NRZ-OOK signal at BER=10 -9. In addition, a reasonable dispersion tolerance of the converted signal up to plusmn500 ps/nm is observed. The numerical simulation based upon the carrier-rate equation verifies the experimental results

NRZ-OOK-to-RZ-BPSK modulation-format conversion using SOA-MZI wavelength converter

A novel all-optical modulation format conversion from non-return-to-zero on-off-keying (NRZ-OOK) to return-to-zero quadrature-phase-shift-keying (RZ-QPSK) is proposed and experimentally demonstrated. The proposed format conversion scheme is based on parallel Mach-Zehnder interferometric (MZI) OOK/binary-PSK (BPSK) converters, consisting of integrated semiconductor optical amplifiers (SOAs). We experimentally demonstrate that in both decoded channels of the converted RZ-QPSK signal bit error rate (BER) curves show almost the same receiver sensitivity at a symbol-rate of 10.7 Gsymbol/s. In addition, a reasonable dispersion tolerance of the converted signal up to +295 ps/nm is observed. The numerical simulation based upon carrier rate equation verifies the experimental results.

All-optical modulation format conversion from NRZ-OOK to RZ-QPSK using parallel SOA-MZI OOK/BPSK converters.

Harmonic distortion of distributed feedback laser diodes (DFB-LDs) for analog transmission systems is investigated. It is shown that, under a modulation frequency of less than 1 GHz, the harmonic distortion depends on the nonlinearity of the light output power-current (P-I) curve under the continuous wave (CW) condition, which is determined by the coupling constant kappa L, and that the distortion can be minimized at kappa L approximately 1. A 1.3 mu m wavelength InGaAsP DFB-PPIBH (p-substrate partially inverted buried heterostructure) LD and its module, with low distortion by the control of a coupling constant, have been developed. >

Distributed feedback laser diode and module for CATV systems

Why Not Tax Uniformly Rather than Optimally

Bulk InGaAsP SOA-MZI monolithic wavelength converter has been optimized for fast gain recovery and clear eye openings at 40Gbps-NRZ format. Full C-band operation and polarization-insensitive operation were achieved at 40Gbps-NRZ.

Tatsuo Hatta

Papers

NRZ-OOK-to-RZ-BPSK modulation-format conversion using SOA-MZI wavelength converter

All-optical modulation format conversion from NRZ-OOK to RZ-QPSK using parallel SOA-MZI OOK/BPSK converters.

Distributed feedback laser diode and module for CATV systems

Why Not Tax Uniformly Rather than Optimally

Polarization-Insensitive SOA-MZI Monolithic All-Optical Wavelength Converter for Full C-band 40Gbps-NRZ Operation