scholarly journals Encircled Angular Flux Representation of the Modal Power Distribution and Its Behavior in a Step Index Multimode Fiber

2016 ◽  
Vol 34 (3) ◽  
pp. 943-951 ◽  
Author(s):  
Manabu Kagami ◽  
Akari Kawasaki ◽  
Masatoshi Yonemura ◽  
Makoto Nakai ◽  
Pablo V. Mena ◽  
...  
Keyword(s):  
Power Distribution ◽  
Multimode Fiber ◽  
Step Index ◽  
Modal Power

Transformation of modal power distribution in multimode fiber with abrupt inhomogeneities

2008 ◽  
Vol 25 (12) ◽  
pp. 1998 ◽  
Author(s):  
O. I. Kotov ◽  
L. B. Liokumovich ◽  
A. H. Hartog ◽  
A. V. Medvedev ◽  
I. O. Kotov
Keyword(s):  
Power Distribution ◽  
Multimode Fiber ◽  
Modal Power

scholarly journals Investigation on Speckle-Free Imaging at the Output of a Multimode Fiber under Various Mode Excitation Conditions

Photonics ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 171
Author(s):  
Jun Zhou ◽  
Zichun Le ◽  
Yanyu Guo ◽  
Zongshen Liu ◽  
Qiyong Xu ◽  
...  
Keyword(s):  
Gaussian Beam ◽  
Tilt Angle ◽  
Power Distribution ◽  
Imaging Systems ◽  
Multimode Fiber ◽  
Speckle Contrast ◽  
Maximum Delay ◽  
Modal Power ◽  
Delay Difference ◽  
Excitation Conditions

Speckle-free imaging using a multimode fiber has been widely used for imaging systems. Generally, previous work has assumed that all the propagating modes of the fiber are uniformly excited, but the modal power distribution is actually affected by excitation conditions. Here, we propose the utilization of a modal analysis method to study the dependence of the speckle contrast on the modal power distribution by changing the tilt angle of the Gaussian beam and on the group delay time difference caused by different fiber lengths. The results of numerical simulations and experiments show that, with an increase in the tilt angle of the Gaussian beam, the modal power is transferred to higher-order modes and the maximum delay difference between excitation modes becomes larger. Therefore, the inter-mode interference effect is effectively weakened, and the speckle contrast is significantly reduced. The increase in fiber length will also make the delay difference between excitation modes larger and thus the speckle contrast is decreased. For the larger tilt angle of the Gaussian beam, only a shorter optical fiber is required to reduce the speckle contrast significantly. Our work further promotes the use of a multimode fiber to produce speckle-free patterns in laser imaging systems.

scholarly journals Equilibrium modal power distribution measurement of step-index hard plastic cladding and graded-index silica multimode fibers

2015 ◽  
Author(s):  
Ruichen Tao ◽  
Takehiro Hayashi ◽  
Manabu Kagami ◽  
Shigeru Kobayashi ◽  
Manabu Yasukawa ◽  
...  
Keyword(s):  
Power Distribution ◽  
Distribution Measurement ◽  
Step Index ◽  
Multimode Fibers ◽  
Graded Index ◽  
Modal Power

scholarly journals Characterization of a Y-Coupler and Its Impact on the Performance of Plastic Optical Fiber Links

Fibers ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 96 ◽  
Author(s):  
Alicia López ◽  
M. Losada ◽  
Javier Mateo ◽  
N. Antoniades ◽  
Xin Jiang ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Power Distribution ◽  
Glass Fibers ◽  
Single Mode ◽  
Transmission Properties ◽  
Modal Power ◽  
Custom Made ◽  
Plastic Optical Fibers ◽  
The Impact

Couplers and splitters are common devices in single-mode and multi-mode glass fibers applications, where they perform a variety of functions. However, when switching to plastic optical fibers (POFs), there is a shortage of commercial devices, which are usually custom-made. The problem with these devices is that modal power distribution in POFs is easily modified by spatial disturbances that produce a localized strong power transfer between modes, thus changing their transmission properties. In this work, a commercial Y-coupler designed for POFs is experimentally characterized. Measurements of its spectral, spatial and temporal characteristics have been performed, including insertion loss as a function of wavelength, angular power distribution, and frequency response. The obtained results show that this device has an equalizing effect over the power spatial distribution that reduces the fiber bandwidth, demonstrating the importance of considering the impact of this type of devices on the transmission properties of any POF system.

scholarly journals Modal reconstruction of transverse mode-locked laser beams

2020 ◽  
Vol 126 (10) ◽  
Author(s):  
Florian Schepers ◽  
Tim Hellwig ◽  
Carsten Fallnich
Keyword(s):  
Power Distribution ◽  
Oscillation Amplitude ◽  
Transverse Mode ◽  
Mode Locking ◽  
Orthogonal Direction ◽  
Modal Power ◽  
Gradient Descent Algorithm ◽  
Stochastic Parallel Gradient Descent ◽  
Spatio Temporal ◽  
Mode Order

Abstract Transverse mode-locking in an end-pumped solid state laser by amplitude modulation with an acousto-optic modulator was investigated. Using the stochastic parallel gradient descent algorithm the modal power coefficients and the modal phases of the transverse mode-locked (TML) laser beam were reconstructed from the measured spatial and spatio-temporal intensity distributions, respectively. The distribution of the reconstructed modal power coefficients revealed that the average mode order of the transverse mode-locking process could be increased by a factor of about 8 compared to previous works, corresponding to an increase in the normalized oscillation amplitude by a factor of about 3. Furthermore, we found that besides a non-Poissonian modal power distribution, strong aberrations of the modal phases occurred in the experiment, resulting in a deformation of the oscillating spot. Additionally, we demonstrated the generation of up to four spots oscillating simultaneously on parallel traces by operating the TML laser on a higher mode order in the orthogonal direction to the transverse mode-locking process. TML lasers are of interest, e.g., for beam scanning purposes, as they have the potential to enable spot resolving rates in the multi-GHz regime.

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