scholarly journals Interference of speckle patterns projected by multimode fibers

2015 ◽  
Author(s):  
M. Lomer ◽  
L. Rodriguez-Cobo ◽  
F. Madruga ◽  
J. M. Lopez-Higuera
Keyword(s):  
Multimode Fibers ◽  
Speckle Patterns

scholarly journals Image reconstruction through a multimode fiber with a simple neural network architecture

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Changyan Zhu ◽  
Eng Aik Chan ◽  
You Wang ◽  
Weina Peng ◽  
Ruixiang Guo ◽  
...  
Keyword(s):  
Neural Network ◽  
Image Reconstruction ◽  
Network Architecture ◽  
Neural Network Architecture ◽  
Training Time ◽  
Modal Dispersion ◽  
Multimode Fibers ◽  
Speckle Patterns ◽  
Hidden Layer ◽  
Simple Neural Network

AbstractMultimode fibers (MMFs) have the potential to carry complex images for endoscopy and related applications, but decoding the complex speckle patterns produced by mode-mixing and modal dispersion in MMFs is a serious challenge. Several groups have recently shown that convolutional neural networks (CNNs) can be trained to perform high-fidelity MMF image reconstruction. We find that a considerably simpler neural network architecture, the single hidden layer dense neural network, performs at least as well as previously-used CNNs in terms of image reconstruction fidelity, and is superior in terms of training time and computing resources required. The trained networks can accurately reconstruct MMF images collected over a week after the cessation of the training set, with the dense network performing as well as the CNN over the entire period.

scholarly journals Space division multiplexing in standard multi-mode optical fibers based on speckle pattern classification

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jaël Pauwels ◽  
Guy Van der Sande ◽  
Guy Verschaffelt
Keyword(s):  
Optical Fibers ◽  
Speckle Pattern ◽  
Single Mode ◽  
Optical Signal ◽  
Optical Signals ◽  
Multimode Fibers ◽  
Space Division Multiplexing ◽  
Space Division ◽  
Speckle Patterns

AbstractIn optical communications the transmission bandwidth of single mode optical fibers is almost fully exploited. To further increase the capacity of a telecommunication link, multiplexing techniques can be applied across 5 physical dimensions: amplitude, quadrature, polarization, frequency and space, with all but the latter being nearly exhausted. We experimentally demonstrate the feasibility of an original space division multiplexing technique based on the classification of speckle patterns measured at the fiber’s output. By coupling multiple optical signals into a standard multimode optical fiber, speckle patterns arise at the fiber’s end facet. This is due to quasi-random interference between the excited modes of propagation. We show how these patterns depend on the parameters of the optical signal beams and the fiber length. Classification of the speckle patterns allows the detection of the independent signals: we can detect the state (i.e. on or off  ) of different beams that are multiplexed in the fiber. Our results show that the proposed space division multiplexing on standard multimode fibers is robust to mode-mixing and polarization scrambling effects.

scholarly journals Active wavefront shaping for controlling and improving multimode fiber sensor

2019 ◽  
Vol 12 (04) ◽  
pp. 1942007 ◽  
Author(s):  
Tianting Zhong ◽  
Zhipeng Yu ◽  
Huanhao Li ◽  
Zihao Li ◽  
Haohong Li ◽  
...  
Keyword(s):  
Light Intensity ◽  
Light Propagation ◽  
Twist Angle ◽  
Measurement Range ◽  
Multimode Fiber ◽  
Multimode Fibers ◽  
Light Pattern ◽  
Speckle Patterns ◽  
Wavefront Shaping ◽  
Control Light

Wavefront shaping (WFS) techniques have been used as a powerful tool to control light propagation in complex media, including multimode fibers. In this paper, we propose a new application of WFS for multimode fiber-based sensors. The use of a single multimode fiber alone, without any special fabrication, as a sensor based on the light intensity variations is not an easy task. The twist effect on multimode fiber is used as an example herein. Experimental results show that light intensity through the multimode fiber shows no direct relationship with the twist angle, but the correlation coefficient (CC) of speckle patterns does. Moreover, if WFS is applied to transform the spatially seemingly random light pattern at the exit of the multimode fiber into an optical focus. The focal pattern correlation and intensity both can serve to gauge the twist angle, with doubled measurement range and allowance of using a fast point detector to provide the feedback. With further development, WFS may find potentials to facilitate the development of multimode fiber-based sensors in a variety of scenarios.

Laser Oscillation in Aggregates of Ultrasmall Si Nanoparticles

2002 ◽  
Vol 728 ◽  
Author(s):  
Munir H. Nayfeh
Keyword(s):  
Stimulated Emission ◽  
Gaussian Beams ◽  
Single Particles ◽  
Nonlinear Characteristics ◽  
Femtosecond Radiation ◽  
Highly Nonlinear ◽  
Line Narrowing ◽  
Si Nanoparticles ◽  
Speckle Patterns ◽  
Spectral Line Narrowing

AbstractWe dispersed electrochemically etched Si into ultrabright ultrasmall nanoparticles, with brightness higher than fluorescein or rhodamine. The emission from single particles is readily detectable. Aggregates or films of the particles exhibit emission with highly nonlinear characteristics. We observe directed blue beams at ∼ 410 nm between faces of aggregates excited by femtosecond radiation at 780 nm; and at ∼ 610 nm from aggregates of red luminescent Si nanoparticles excited by radiation at 550-570 nm from a mercury lamp. Intense directed Gaussian beams, a pumping threshold, spectral line narrowing, and speckle patterns manifest the emission. The results are analyzed in terms of population inversion and stimulated emission in quantum confinement-induced Si-Si dimer phase, found only on ultrasmall Si nanoparticles. This microlasing constitutes an important step towards the realization of a laser on a chip.

Thermal stresses applied on helicopter blades useful to retrieve defects by means of infrared thermography and speckle patterns

2020 ◽  
Vol 18 ◽  
pp. 100511
Author(s):  
F. López ◽  
S. Sfarra ◽  
A. Chulkov ◽  
C. Ibarra-Castanedo ◽  
H. Zhang ◽  
...  
Keyword(s):  
Infrared Thermography ◽  
Thermal Stresses ◽  
Helicopter Blades ◽  
Speckle Patterns

SPECKLE STATISTICS IN THE PHOTON LOCALIZATION TRANSITION

2010 ◽  
Vol 24 (12n13) ◽  
pp. 1950-1988 ◽  
Author(s):  
Azriel Z. Genack ◽  
Jing Wang
Keyword(s):  
Steady State ◽  
Probability Distributions ◽  
Speckle Pattern ◽  
Frequency Variation ◽  
Localization Transition ◽  
Classical Waves ◽  
Speckle Patterns ◽  
The Many ◽  
Photon Localization ◽  
State Propagation

We review the statistics of speckle in the Anderson localization transition for classical waves. Probability distributions of local and integrated transmission and of the evolution of the structure of the speckle pattern are related to their corresponding correlation functions. Steady state and pulse transport can be described in terms of modes whose speckle patterns are obtained by decomposing the frequency variation of the transmitted field. At the same time, transmission can be purposefully manipulated by adjusting the incident field and the eigenchannels of the transmission matrix can be found by analyzing sets of speckle patterns for different inputs. The many aspects of steady state propagation are reflected in diverse, but simply related, parameters so that a single localization parameter encapsulates the character of transport on both sides of the divide separating localized from diffusive waves.

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