Amirhossein Mohajerin-Ariaei

Bio: Amirhossein Mohajerin-Ariaei is an academic researcher from University of Southern California. The author has contributed to research in topics: Phase-shift keying & Phase noise. The author has an hindex of 13, co-authored 97 publications receiving 547 citations.

All-Optical Signal Processing Techniques for Flexible Networks

Abstract: This tutorial highlights challenges and opportunities in achieving efficient flexible optical networks. Optical signal processing may potentially increase network flexibility because of its functions’ transparency, tunability, and reconfigurability. We review recent advances in high-speed optical signal processing techniques that might enable flexible networks. Various optical approaches that enable key functions are discussed, including format conversion, increases in spectral efficiency, and phase-sensitive operations. We also discuss the potential utilization of basic enabling technologies, such as optical frequency combs and optical nonlinear devices.

Demonstration of in-service wavelength division multiplexing optical-signal-to-noise ratio performance monitoring and operating guidelines for coherent data channels with different modulation formats and various baud rates.

Abstract: We demonstrated a delay-line interferometer (DLI)-based, optical-signal-to-noise ratio (OSNR) monitoring scheme of 100 Gbit/s polarization multiplexed quadrature-phase-shift-keying (PM-QPSK) four-channel WDM at 50-GHz International Telecommunication Union (ITU) grid with <0.5 dB error for signals with up to 26 dB of actual OSNR. We also demonstrated data format transparency and baud rate tunability of the OSNR monitor by measuring the OSNR for a 200 Gbit/s PM-16-QAM (25-Gbaud) signal and a 200 Gbit/s PM-QPSK (50-Gbaud) signal. We also explored and studied different monitor parameters, including the shape of the filter spectrum, the bandwidth of the filter, DLI delay, and DLI phase-detuning to determine the design guidelines for a desired level of accuracy for the OSNR monitor in an optical network.

Dependence of a microresonator Kerr frequency comb on the pump linewidth.

Abstract: We experimentally investigate the dependence of Kerr comb generation, comb linewidth, and coherent system performance on the pump linewidth in a microresonator. We find that the generation of the primary comb can have a larger tolerance to the pump linewidth compared with that of the low-phase-noise comb. In addition, the linewidths of the generated combs are almost linearly dependent on the pump linewidth in the primary and low-phase-noise states. Furthermore, the optical signal-to-noise ratio penalty between the pump and generated Kerr combs in a coherent communication system is less than 0.2 dB in both the primary and low-phase-noise states, showing that Kerr frequency combs in these two states can have similar coherent system performance to the pump.

Digital optical processing of optical communications: towards an Optical Turing Machine

Abstract: Abstract Optical computing is needed to support Tb/s in-network processing in a way that unifies communication and computation using a single data representation that supports in-transit network packet processing, security, and big data filtering. Support for optical computation of this sort requires leveraging the native properties of optical wave mixing to enable computation and switching for programmability. As a consequence, data must be encoded digitally as phase (M-PSK), semantics-preserving regeneration is the key to high-order computation, and data processing at Tb/s rates requires mixing. Experiments have demonstrated viable approaches to phase squeezing and power restoration. This work led our team to develop the first serial, optical Internet hop-count decrement, and to design and simulate optical circuits for calculating the Internet checksum and multiplexing Internet packets. The current exploration focuses on limited-lookback computational models to reduce the need for permanent storage and hybrid nanophotonic circuits that combine phase-aligned comb sources, non-linear mixing, and switching on the same substrate to avoid the macroscopic effects that hamper benchtop prototypes.

Pilot-tone-based self-homodyne detection using optical nonlinear wave mixing.

Abstract: An all-optical pilot-tone-based self-homodyne detection scheme using nonlinear wave mixing is experimentally demonstrated. Two scenarios are investigated using (1) multiple wavelength-division-multiplexed channels with sufficient power of the pilot tones and (2) a single channel with a low-power pilot tone. The eye diagram and bit error rate of the system are studied by tuning various parameters such as pump power, relative phase, and pilot-to-signal ratio.

Photonic-chip-based frequency combs

Abstract: Recent developments in chip-based nonlinear photonics offer the tantalizing prospect of realizing many applications that can use optical frequency comb devices that have form factors smaller than 1 cm3 and that require less than 1 W of power. A key feature that enables such technology is the tight confinement of light due to the high refractive index contrast between the core and the cladding. This simultaneously produces high optical nonlinearities and allows for dispersion engineering to realize and phase match parametric nonlinear processes with laser-pointer powers across large spectral bandwidths. In this Review, we summarize the developments, applications and underlying physics of optical frequency comb generation in photonic-chip waveguides via supercontinuum generation and in microresonators via Kerr-comb generation that enable comb technology from the near-ultraviolet to the mid-infrared regime. This Review discusses the developments and applications of on-chip optical frequency comb generation based on two concepts—supercontinuum generation in photonic-chip waveguides and Kerr-comb generation in microresonators.

All-Optical Signal Processing

Abstract: Optical signal processing brings together various fields of optics and signal processing - namely, nonlinear devices and processes, analog and digital signals, and advanced data modulation formats - to achieve high-speed signal processing functions that can potentially operate at the line rate of fiber optic communications. Information can be encoded in amplitude, phase, wavelength, polarization and spatial features of an optical wave to achieve high-capacity transmission. We revisit advances in the key enabling technologies that led to recent research in optical signal processing for digital signals that are encoded in one or more of these dimensions. Various optical nonlinearities and chromatic dispersion have been shown to enable key sub-system applications such as wavelength conversion, multicasting, multiplexing, demultiplexing, and tunable optical delays. We review recent advances in high-speed optical signal processing applications in the areas of equalization, regeneration, flexible signal generation, and optical control information (optical logic and correlation).

Fiber-based Optical Parametric Amplifiers and Their Applications

Abstract: The theoretical fundamentals of fiber-based optical parametric amplifiers(OPA) are reviewed,and their applications are discussed in this paper.In the end the future research aspects are expected.

RF Photonics: An Optical Microcombs’ Perspective

Abstract: Over the past decade, optical frequency combs generated by high-Q microresonators, or optical microcombs, which feature compact device footprints, low power consumption, and high repetition rates in broad optical bandwidths, have led to a revolution in a wide range of fields including metrology, telecommunications, radio frequency (RF) photonics, spectroscopy, sensing, and quantum optics. Among these, an application that has attracted great interest is the use of optical microcombs for RF photonics, where they offer enhanced functionalities as well as reduced size and power consumption over other approaches. This paper reviews the recent advances in this emerging field. We provide an overview of the main achievements that have been obtained to date, and highlight the strong potential of optical microcombs for RF photonics applications. We also discuss some of the open challenges and limitations that need to be addressed for practical applications.

Optical Performance Monitoring: A Review of Current and Future Technologies

Abstract: Optical performance monitoring (OPM) is the estimation and acquisition of different physical parameters of transmitted signals and various components of an optical network. OPM functionalities are indispensable in ensuring robust network operation and plays a key role in enabling flexibility and improve overall network efficiency. We review the development of various OPM techniques for direct-detection systems and digital coherent systems and discuss future OPM challenges in flexible and elastic optical networks.