Lothar Möller

Bio: Lothar Möller is an academic researcher from Bell Labs. The author has contributed to research in topics: Polarization mode dispersion & Polarization rotator. The author has an hindex of 18, co-authored 75 publications receiving 1021 citations. Previous affiliations of Lothar Möller include Alcatel-Lucent.

160 Gbit/s SOA all-optical wavelength converter and assessment of its regenerative properties

Abstract: The retiming and reshaping properties of a 160 Gbit/s all-optical wavelength converter based on a semiconductor optical amplifier gating delay interferometer configuration is investigated. 160 Gbit/s operation is performed with as little as -3.5 dBm input signal.

Wavelength blocking filter with flexible data rates and channel spacing

Abstract: This work presents a high-resolution (13.2 GHz) channel-blocking optical filter, suitable for use as a reconfigurable optical add/drop multiplexer (ROADM), which seamlessly supports data rates from 2.5 to 160 Gb/s. The filter consists of a linear array of 64 MEMS micromirrors and a high-dispersion echelle grating. The demonstrated device had an insertion loss of 9 dB, a loss ripple of 1.2 dB, and a group delay ripple of 15 ps. Data transmission through the device with various mixed data rate scenarios ranging from 2.5 to 160 Gb/s showed negligible penalty, except at 40 Gb/s where a maximum penalty of 1.5 dB was observed due to a phase coherence with the blocker filter ripple.

Comparison of system tolerance to polarization-mode dispersion between different modulation formats

Abstract: The polarization-mode dispersion (PMD) tolerance of different modulation formats is studied, including ON-OFF keyed (OOK), differential phase-shift keyed (DPSK), and carrier-suppressed return-to-zero (CSRZ) formats. It is shown that, generally, for PMD uncompensated systems, the modulation formats with larger pulsewidth have larger penalty, while the modulation formats with smaller bandwidth perform better in PMD compensated systems. It is also shown that DPSK can tolerate more PMD than OOK for both PMD uncompensated and compensated systems, and that CSRZ, because of its specific spectrum characteristics, has a different feature from return-to-zero formats.

Data encoding on terahertz signals for communication and sensing

Abstract: We demonstrate and analyze data modulation of terahertz (THz) signals in the 1 Mbit/s range. THz pulse trains are phase and amplitude encoded with pseudorandom binary data, transmitted over a short distance, and detected. Different modulation formats are generated. Bit error measurements characterize the communication channel. We estimate from experimental results the maximum data rates for an optimized system.

Suppression of intrachannel nonlinear effects with alternate-polarization formats

Abstract: We investigate using alternate-polarization (APol) on-off keying formats, in which adjacent bits have orthogonal states of polarization, to suppress intrachannel nonlinear impairments in dispersion-managed (DM) optical fiber transmission systems. Simple methods to generate the APol formats are discussed, and the transmission performance of the APol formats for both 40-Gb/s DM systems and 10-Gb/s DM-soliton systems is experimentally studied. We show that the APol formats can significantly improve the performance of 40-Gb/s DM transmission systems, while the improvement of 10-Gb/s systems is smaller.

Spectrum-efficient and scalable elastic optical path network: architecture, benefits, and enabling technologies

Abstract: The sustained growth of data traffic volume calls for an introduction of an efficient and scalable transport platform for links of 100 Gb/s and beyond in the future optical network. In this article, after briefly reviewing the existing major technology options, we propose a novel, spectrum- efficient, and scalable optical transport network architecture called SLICE. The SLICE architecture enables sub-wavelength, superwavelength, and multiple-rate data traffic accommodation in a highly spectrum-efficient manner, thereby providing a fractional bandwidth service. Dynamic bandwidth variation of elastic optical paths provides network operators with new business opportunities offering cost-effective and highly available connectivity services through time-dependent bandwidth sharing, energy-efficient network operation, and highly survivable restoration with bandwidth squeezing. We also discuss an optical orthogonal frequency-division multiplexing-based flexible-rate transponder and a bandwidth-variable wavelength cross-connect as the enabling technologies of SLICE concept. Finally, we present the performance evaluation and technical challenges that arise in this new network architecture.

Review of terahertz and subterahertz wireless communications

Abstract: According to Edholm’s law, the demand for point-to-point bandwidth in wireless short-range communications has doubled every 18 months over the last 25 years It can be predicted that data rates of around 5–10 Gb/s will be required in ten years In order to achieve 10 Gb/s data rates, the carrier frequencies need to be increased beyond 100 GHz Over the past ten years, several groups have considered the prospects of using sub-terahertz (THz) and THz waves (100–2000 GHz) as a means to transmit data wirelessly Some of the reported advantages of THz communications links are inherently higher bandwidth compared to millimeter wave links, less susceptibility to scintillation effects than infrared wireless links, and the ability to use THz links for secure communications Our goal of this paper is to provide a comprehensive review of wireless sub-THz and THz communications

Advanced Optical Modulation Formats

Abstract: Fiber-optic communication systems form the high-capacity transport infrastructure that enables global broadband data services and advanced Internet applications. The desire for higher per-fiber transport capacities and, at the same time, the drive for lower costs per end-to-end transmitted information bit has led to optically routed networks with high spectral efficiencies. Among other enabling technologies, advanced optical modulation formats have become key to the design of modern wavelength division multiplexed (WDM) fiber systems. In this paper, we review optical modulation formats in the broader context of optically routed WDM networks. We discuss the generation and detection of multigigabit/s intensity- and phase-modulated formats, and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, multipath interference, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity

Elastic Bandwidth Allocation in Flexible OFDM-Based Optical Networks

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) has recently been proposed as a modulation technique for optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments. We consider the planning problem of an OFDM optical network, where we are given a traffic matrix that includes the requested transmission rates of the connections to be served. Connections are provisioned for their requested rate by elastically allocating spectrum using a variable number of OFDM subcarriers and choosing an appropriate modulation level, taking into account the transmission distance. We introduce the Routing, Modulation Level and Spectrum Allocation (RMLSA) problem, as opposed to the typical Routing and Wavelength Assignment (RWA) problem of traditional WDM networks, prove that is also NP-complete and present various algorithms to solve it. We start by presenting an optimal ILP RMLSA algorithm that minimizes the spectrum used to serve the traffic matrix, and also present a decomposition method that breaks RMLSA into its two substituent subproblems, namely 1) routing and modulation level and 2) spectrum allocation (RML+SA), and solves them sequentially. We also propose a heuristic algorithm that serves connections one-by-one and use it to solve the planning problem by sequentially serving all the connections in the traffic matrix. In the sequential algorithm, we investigate two policies for defining the order in which connections are considered. We also use a simulated annealing meta-heuristic to obtain even better orderings. We examine the performance of the proposed algorithms through simulation experiments and evaluate the spectrum utilization benefits that can be obtained by utilizing OFDM elastic bandwidth allocation, when compared to a traditional WDM network.

Routing and Spectrum Allocation in Elastic Optical Networks: A Tutorial

Abstract: Flexgrid technology is now considered to be a promising solution for future high-speed network design. In this context, we need a tutorial that covers the key aspects of elastic optical networks. This tutorial paper starts with a brief introduction of the elastic optical network and its unique characteristics. The paper then moves to the architecture of the elastic optical network and its operation principle. To complete the discussion of network architecture, this paper focuses on the different node architectures, and compares their performance in terms of scalability and flexibility. Thereafter, this paper reviews and classifies routing and spectrum allocation (RSA) approaches including their pros and cons. Furthermore, various aspects, namely, fragmentation, modulation, quality-of-transmission, traffic grooming, survivability, energy saving, and networking cost related to RSA, are presented. Finally, the paper explores the experimental demonstrations that have tested the functionality of the elastic optical network, and follows that with the research challenges and open issues posed by flexible networks.