The compelling demand for higher performance and lower power consumption in electronic systems is the main driving force of the electronics industry's quest for devices and/or architectures based on new materials. Here, we provide a review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches. We focus on the performance limits and advantages of these materials and associated technologies, when exploited for both digital and analog applications, focusing on the main figures of merit needed to meet industry requirements. We also discuss the use of two-dimensional materials as an enabling factor for flexible electronics and provide our perspectives on future developments.

Electronics based on two-dimensional materials

We review the current status of single-photon-source and single-photon-detector technologies operating at wavelengths from the ultraviolet to the infrared. We discuss applications of these technologies to quantum communication, a field currently driving much of the development of single-photon sources and detectors.

/pdf/invited-review-article-single-photon-sources-and-detectors-5bsn8auo37.pdf

Invited review article: Single-photon sources and detectors

The current status of lithium-niobate external-modulator technology is reviewed with emphasis on design, fabrication, system requirements, performance, and reliability. The technology meets the performance and reliability requirements of current 2.5-, 10-, and 40-Gb/s digital communication systems, as well as CATV analog systems. The current trend in device topology is toward higher data rates and increased levels of integration. In particular, multiple high-speed modulation functions, such as 10-Gb/s return-to-zero pulse generation plus data modulation, have been achieved in a single device.

/pdf/a-review-of-lithium-niobate-modulators-for-fiber-optic-1s6rskx8q3.pdf

A review of lithium niobate modulators for fiber-optic communications systems

Digital filters underpin the performance of coherent optical receivers which exploit digital signal processing (DSP) to mitigate transmission impairments. We outline the principles of such receivers and review our experimental investigations into compensation of polarization mode dispersion. We then consider the details of the digital filtering employed and present an analytical solution to the design of a chromatic dispersion compensating filter. Using the analytical solution an upper bound on the number of taps required to compensate chromatic dispersion is obtained, with simulation revealing an improved bound of 2.2 taps per 1000ps/nm for 10.7GBaud data. Finally the principles of digital polarization tracking are outlined and through simulation, it is demonstrated that 100krad/s polarization rotations could be tracked using DSP with a clock frequency of less than 500MHz.

Digital filters for coherent optical receivers.

Optical fiber transmission is impacted by linear and nonlinear impairments. We study the use of digital backpropagation (BP) in conjunction with coherent detection to jointly mitigate dispersion and fiber nonlinearity. We propose a noniterative asymmetric split-step Fourier method (SSFM) for solving the inverse nonlinear Schrodinger equation (NLSE). Using simulation results for RZ-QPSK transmitted over terrestrial systems with inline amplification and dispersion compensation, we obtain heuristics for the step size and sampling rate requirements, as well as the optimal dispersion map.

Compensation of Dispersion and Nonlinear Impairments Using Digital Backpropagation

We have proposed and demonstrated a novel method of realizing a shape-controllable narrowband optical filter using SBS in an optical fiber. By BPSK modulating the pump light with deliberately coded binary data patterns, various types of bandpass filters as well as notch filters were realized. These may be exploited as powerful tools in optical signal processing. Moreover, the bandwidth can be further broadened for dense wavelength division multiplexing (DWDM) applications, by using a long highly-nonlinear fiber with a large SBS gain.

Shape-controllable narrowband optical filter using stimulated Brillouin scattering

We show that the classical model of the amplifier noise can well describe the amplifier-noise characteristics and that the signalgain, the spontaneous emission factor, and the optical bandwidth are all the information necessary for analyzing the amplifier-noise characteristics. The accumulation of noise in the amplifier chain is also discussed in detail.

Theory of noise in optical amplifiers

PROBLEM TO BE SOLVED: To inexpensively provide an optical dispersion compensating element having such superior group velocity retardation time-wavelength characteristics that it can perform satisfactory dispersion compensation, particularly tertiary dispersion compensation even in a wide wavelength range in which a conventional element cannot be put to practical use as a miniature element easy to use, ensuring a small loss and having high reliability in a state suitable for mass production SOLUTION: The miniature highly stable optical dispersion compensating element ensuring a small loss and usable in a wide band is obtained by disposing multilayer films having dispersion compensating function on the opposite faces of a substrate capable of transmitting signal light in such a way that the planes of incidence confront each other Dispersion compensation is performed by reflecting signal light a plurality of times between the opposite multilayer films

Optical dispersion compensating element

Using the newly developed eye-construction algorithm, we demonstrate a cost-effective all-optical sampling system, incorporating a free-running sampling pulse source. Polarization-insensitive eye-diagram construction of 160-Gb/s signals is realized at 0.3 sec/scan in the entire C band.

Real-Time All-Optical Waveform Sampling Using a Free-Running Passively Mode-Locked Fiber Laser as the Sampling Pulse Source

We present a new linewidth formula for DFB lasers, which includes the spatial hole burning effect. The linewidth of DFB lasers with three separated electrodes is calculated in various bias conditions. The optimum bias condition is discussed to obtain a narrow linewidth.

Kazuro Kikuchi

Papers

Shape-controllable narrowband optical filter using stimulated Brillouin scattering

Theory of noise in optical amplifiers

Optical dispersion compensating element

Real-Time All-Optical Waveform Sampling Using a Free-Running Passively Mode-Locked Fiber Laser as the Sampling Pulse Source

Analysis of linewidth of separated-electrode DFB laser diode