Optical Feedback By Four Wave Mixing In Optical Processing Systems

This work presents an integrated framework combining optical signal processing and VLSI system design for the performance evaluation and optimization of 5G waveform candidates under different modulation schemes. The analysis focuses on four major waveforms – OFDM, FBMC, NOMA, and OTFS – and examines their performance based on bit error rate (BER), peak-to-average power ratio (PAPR), and power spectral density (PSD) metrics. Simulation results demonstrate that OTFS outperforms the other waveforms, achieving a BER of 10 −3 at an SNR range of 7–10 dB, corresponding to an SNR gain of up to 8 dB over OFDM. Furthermore, OTFS exhibits a PAPR reduction of approximately 3.5 dB and the lowest out-of-band emissions with a PSD of around −310 dBW/MHz, indicating superior spectral efficiency and reduced interference. These characteristics make OTFS a promising waveform for high-mobility, high-capacity 5G and future 6G communication environments. The integration of optical signal processing techniques enhances system bandwidth and energy efficiency, while VLSI-based architectures support low-latency, high-throughput implementation. Future advancements will explore optical-VLSI codesign and machine learning–assisted frameworks for real-time adaptive processing, improving scalability, power optimization, and intelligent signal handling in next-generation wireless and optical communication systems.

The distributed fibre optic sensors (DFOSs) provide measurement all along the length of the fibre. It operates on the principle of optical time domain reflectometry where the properties of the backscattered light are used to sense the variations in physical parameters. The short- and high-peak power light pulses are launched into the fibre in DFOS. The amplitude of the backscattered pulses is very small, in the range of pico- to nanoamperes, due to various attenuations. Also, the pulse width of the light needs to be small, in nanoseconds range, to have high spatial resolution. Thus, to detect such high-speed weak amplitude pulses, a very sophisticated optical signal processing (OSP) system is required that converts the entire pulsed light information into an analogue millivolts signal. The paper describes the design criteria of such OSP system that requires proper selection of photodiodes and op-amps to be implemented as transimpedance amplifiers. The paper also provides the simulation results obtained after component selection and designing of the circuit. The important considerations for preparing the circuit board layout for such noise-prone signals before PCB manufacturing are also highlighted. The hardware circuit of the system was developed and tested. The test results are also provided. The simulation results together with the hardware results confirm the rise time of nanoseconds of the output pulses which ensures that the design meets the critical criteria of possessing wide bandwidth and sufficient gain to detect the backscattered pulses and convert them into an analogue signal. The OSP system developed is very cost-effective that can help in overall cost reduction of the DFOS.KeywordsDistributed fibre optic sensorOptical signal processingPhotodiodeTransimpedance amplifier

Spatial light modulators (SLM) are electro-optical devices employed as optical pattern generators in applications like projection displays, direct-writing systems for photolithographic patterning, adaptive optics or optical signal processing. Here we report on the “moving liquid mirror” (MLM) as a new micromechanical actuator technology based on a deformable oil film on an aluminum mirror with electrode structure. The actuator is suitable for integration on a silicon backplane as CMOS-addressing circuit. Thus production in standard CMOS-technology is possible. A theoretical analysis of the device behavior is given, and the results of simulations are presented. Measurements on passive devices show good agreement with the simulations. Finally, active MLM-devices have been fabricated. Images can be programmed into the devices and observed under a microscope (figure 1).

We discuss the light signals that are coherently emitted by some optical absorbers sub-sequent to excitation by a series of three laser excitation pulses. In some cases, the light signal emitted by the material duplicates the temporal shape of one of the laser in-put pulses. In other cases, the emitted signal represents the convolution or cross-correlation of two of the laser input pulses. In principle, digitally encoded signals of multi-gigahertz bandwidth can be convolved in real time, or, in suitable materials, stored for long periods. Output signals on the order of a few percent as intense as the inputs are possible. We provide experimental demonstrations of these effects, and discuss their implementation in optical signal processing and data storage systems.

This research explores the extended (3+1)-dimensional Kairat–II equation by employing the logistic equation method and the modified Kudryashov approach. The Kairat family of equations is notable for capturing second-order spatiotemporal dispersion and group velocity dispersion, which are significant in the study of curve differential geometry and various equivalence relations. The extended form of the equation introduces three additional linear diffusion terms, enriching the physical phenomena already described by the original model. This work presents a range of solitary wave solutions, including their propagation patterns, by applying hyperbolic and trigonometric function-based solutions. These include multiple breather, kink, and other essential wave structures relevant to optical fiber technology, signal processing, and telecommunication systems. Additionally, 3D, 2D, contour and polar coordinate plots are provided to visually represent the analytical soliton dynamics within the extended Kairat equation. The obtained solutions offer new perspectives in fields such as optical communication, fiber optics, oceanography, and quantum mechanics.

Integrated optoelectronics using 111-V compound semiconductor technology is expected to offer new techniques of interconnection and signal processing within electronic digital systems solving the wiring limit in data communication and processing using the advantages of optical technique such as high data transmission rate and high parallelism. Optical interconnection devices are the key to this and the development is being carried out not only to multiplex a vast amount of data but also to provide flexible interconnection functions. This paper summarizes the role and current status of integrated optoelectronics technology for optical interconnections and signal processing systems. 1.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

All-optical Switches based-on GaAs/AlAs Quantum Dots Vertical Cavities

Summary form only given. An overview of the recent progress of ultrafast all-optical devices being developed for the application to optical time-division multiplexing (OTDM) communication and signal processing systems is given. In parallel with active on-going development of wavelength-division multiplexing (WDM) systems, OTDM is another indispensable technique to support the rapidly increasing demand of system throughput. We review recent development of femtosecond all-optical devices such as semiconductor laser light sources, pulse compression devices, and all-optical switches.

Optical fiber pressure sensors have been developed for use on a structurally-adaptive `smart wing'; further details of the design, fabrication and testing of the smart wing concept are presented in companion papers. This paper describes the design, construction, and performance of the pressure sensor and a combined optical and electronic signal processing system implemented to permit the measurement of a large number of sensors distributed over the control surfaces of a wing. Optical fiber pressure sensors were implemented due to anticipated large electromagnetic interference signals within the operational environment. The sensors utilized the principle of the extrinsic Fabry-Perot interferometer (EFPI) already developed for the measurement of strain and temperature. Here, the cavity is created inside a micromachined hollow-core tube with a silicon diaphragm at one end. The operation of the sensor is similar to that of the EFPI strain gage also discussed in several papers at this conference. The limitations placed upon the performance of the digital signal processing system were determined by the required pressure range of the sensors and the cycle time of the control system used to adaptively modify the shape of the wing. Sensor calibration and the results of testing performed are detailed.

By using nonlinearity and optical feedback the flexibility of optical processing can be increased. Logarithm, equi-density contour mapping, and A/D conversion are nonlinear operations which have already been successfully implemented with halftone screen processes [1–3]. These and other nonlinear operations as well as optical digital processing can be performed by suitable image thresholding and planar logic devices [4,5]. To accomplish optical feedback, partially reflecting mirrors have been utilized [5–7]. Optical processing systems with coherent feedback allow for the realization of the well-known feedback transfer function in two dimensions. In this paper some progress during the last year in the studies at UCSD involving nonlinear optical devices and optical feedback is reported, together with brief reviews of relevant background information.

Recent advances in electro-optics have brought into use communication and information theory to analyze performance in coherent and incoherent optical information processing systems. An optical information processsing system can be analyzed with many of the same concepts of linear system theory (e.g., spatial impulse response, spatial frequency and spatial domain synthesis, etc.), and the photographic images to be processed can be regarded in the same manner as time signals (e.g., spatial frequency content, spatial amplitude and phase modulation, space-bandwidth product, etc.). Both coherent and incoherent optical processing systems can be treated as linear systems, and the processing operation can generally be carried out by communication theory concepts. Although coherent optical information processing operations have been used for performing complex amplitude operations, complex processing can also be performed with incoherent or white-light illumination. The importance of optical information processing operations, either coherent or incoherent, is due to the basic Fourier transform properties of lenses. In this paper, we will discuss mostly the incoherent systems because they are of more recent interest and possess certain advantages, we feel, over the traditional coherent optical processors. Experimental illustrations of the results are provided. In view of the broad area in optical processing of photographic images, we will confine ourselves to a few applications that we consider of general interest. We apologize for the omission of other techniques and applications, and for neglecting the inclusion of their references.

Acousto-optic methods are widely used not only in devices and systems for radio and optical signal processing, but also for studying physical properties of various materials. The paper presents the results of the investigation of the non-resonance (due to native piezoelectric effect) generation of elastic waves at super high frequencies in the Bi 12 GeO 20 crystal, using the acousto-optic method. Acoustic field patterns are visualized in various crystal cuts, including the degenerated acoustic mode in the [111] direction in the crystal. Conditions are discussed under which acoustic modes and directions exist with the self-collimation effect (abnormally low power spread of acoustic wave). Quantitative estimation of collimation quality is made for various conditions. Experimental characteristics of high-order harmonics generation processes appeared due to elastic non-linearity of the material are found. Basing on the experimental data, some parameters of the elastic non-linearity are evaluated.

We modify the optical transfer function of an incoherent imaging system such that it is nearly invariant to misfocus and contains no zero values. Digital filtering of the resulting image restores the image to near diffraction limited spatial resolution. A system that is insensitive to misfocus is also insensitive to some lens aberrations. Consequently, the approach of combining optical and digital signal processing system extends the normal aberration balancing of lens design to include those aberrations that can be reduced by digital signal processing, such as spherical aberration.

We review the recent advancements in the fabrication and application of semiconductor optical fibers. Particular focus is placed on novel materials and device designs for use in optical signal processing systems.

This paper reviews the recent advancements in the fabrication and application of silicon core optical fibers. Particular focus is placed on novel materials and device designs for use in optical signal processing systems. © 2018 Optical Society of America