Mode decomposition of output beams in LD-pumped graded-index fiber Raman lasers

2021 ◽  
Author(s):  
Denis S. Kharenko ◽  
Mikhail D. Gervaziev ◽  
Alexey Kuznetsov ◽  
Stefan Wabnitz ◽  
Evgeniy V. Podivilov ◽  
...  
Keyword(s):  
Graded Index ◽  
Mode Decomposition ◽  
Raman Lasers

Frequency doubling of graded-index fiber Raman lasers with multimode diode pumping

2020 ◽  
Author(s):  
Aleksey G. Kuznetsov ◽  
Ekaterina A. Evmenova ◽  
Ekaterina I. Dontsova ◽  
Sergey I. Kablukov ◽  
Sergey A. Babin
Keyword(s):  
Frequency Doubling ◽  
Diode Pumping ◽  
Graded Index ◽  
Raman Lasers

Seeing the beam cleanup effect in high-power graded-index-fiber Raman amplifier based on mode decomposition

2021 ◽  
Author(s):  
Chenchen Fan ◽  
Yi An ◽  
Tianfu Yao ◽  
Hu Xiao ◽  
Liangjin Huang ◽  
...  
Keyword(s):  
High Power ◽  
Raman Amplifier ◽  
Fiber Raman Amplifier ◽  
Graded Index ◽  
Mode Decomposition

scholarly journals High-brightness all-fiber Raman lasers directly pumped by multimode laser diodes

2019 ◽  
Vol 7 ◽  
Author(s):  
S. A. Babin
Keyword(s):  
Rare Earth ◽  
High Power ◽  
Fiber Lasers ◽  
Mode Selection ◽  
Laser Diodes ◽  
Multimode Laser ◽  
High Brightness ◽  
Graded Index ◽  
Raman Lasers ◽  
Rare Earth Doped

High-brightness fiber laser sources usually utilize active rare-earth-doped fibers cladding-pumped by multimode laser diodes (LDs), but they operate in limited wavelength ranges. Singlemode-passive-fiber based Raman lasers are able to operate at almost any wavelength being pumped by high-power fiber lasers. One of the interesting possibilities is to directly pump graded-index (GRIN) multimode passive fibers by available high-power multimode LDs at 915–940 nm, thus achieving high-power Raman lasing in the wavelength range of 950–1000 nm, which is problematic for rare-earth-doped fiber lasers. Here we review the latest results on the development of all-fiber high-brightness LD-pumped sources based on GRIN fiber with in-fiber Bragg gratings (FBGs). The mode-selection properties of FBGs inscribed by fs pulses supported by the Raman clean-up effect result in efficient conversion of multimode pump into a high-quality output beam at 9xx nm. GRIN fibers with core diameters 62.5, 85 and $100~\unicode[STIX]{x03BC}\text{m}$ are compared. Further scaling capabilities and potential applications of such sources are discussed.

Frequency doubling of multimode diode-pumped graded-index fiber Raman lasers

2019 ◽  
Author(s):  
Alexey G. Kuznetsov ◽  
Ekaterina A. Evmenova ◽  
Sergey I. Kablukov ◽  
Sergey A. Babin
Keyword(s):  
Frequency Doubling ◽  
Graded Index ◽  
Raman Lasers ◽  
Diode Pumped

scholarly journals Cascaded Generation in Multimode Diode-Pumped Graded-Index Fiber Raman Lasers

Photonics ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 447
Author(s):  
Alexey G. Kuznetsov ◽  
Ilya N. Nemov ◽  
Alexey A. Wolf ◽  
Ekaterina A. Evmenova ◽  
Sergey I. Kablukov ◽  
...  
Keyword(s):  
Output Power ◽  
Beam Quality ◽  
Open Cavity ◽  
Stokes Wave ◽  
Linear Cavity ◽  
Multimode Laser ◽  
Rayleigh Backscattering ◽  
Graded Index ◽  
Raman Lasers ◽  
Stokes Generation

We review our recent experimental results on the cascaded Raman conversion of highly multimode laser diode (LD) pump radiation into the first- and higher-order Stokes radiation in multimode graded-index fibers. A linear cavity composed of fiber Bragg gratings (FBGs) inscribed in the fiber core is formed to provide feedback for the first Stokes order, whereas, for the second order, both a linear cavity consisting of two FBGs and a half-open cavity with one FBG and random distributed feedback (RDFB) via Rayleigh backscattering along the fiber are explored. LDs with different wavelengths (915 and 940 nm) are used for pumping enabling Raman lasing at different wavelengths of the first (950, 954 and 976 nm), second (976, 996 and 1019 nm) and third (1065 nm) Stokes orders. Output power and efficiency, spectral line shapes and widths, beam quality and shapes are compared for different configurations. It is shown that the RDFB cavity provides higher slope efficiency of the second Stokes generation (up to 70% as that for the first Stokes wave) with output power up to ~30 W, limited by the third Stokes generation. The best beam quality parameter of the second Stokes beam is close to the diffraction limit (M2~1.3) in both linear and half-open cavities, whereas the line is narrower (<0.2 nm) and more stable in the case of the linear cavity with two FBGs. However, an optimization of the FBG reflection spectrum used in the half-open cavity allows this linewidth value to be approached. The measured beam profiles show the dip formation in the output pump beam profile, whereas the first and second Stokes beams are Gaussian-shaped and almost unchanged with increasing power. A qualitative explanation of such behavior in connection with the power evolution for the transmitted pump and generated first, second and third Stokes beams is given. The potential for wavelength tuning of the cascaded Raman lasers based on LD-pumped multimode fibers is discussed.

Experimental Measurement of In-Plane Rolling Nonpneumatic Tire Vibrations Using High-Speed Imaging

2019 ◽  
Vol 47 (3) ◽  
pp. 196-210
Author(s):  
Meghashyam Panyam ◽  
Beshah Ayalew ◽  
Timothy Rhyne ◽  
Steve Cron ◽  
John Adcox
Keyword(s):  
High Speed ◽  
Image Correlation ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
High Speed Imaging ◽  
Correlation Algorithm ◽  
Mode Decomposition ◽  
Series Of Experiments ◽  
Plane Deformations ◽  
Dominant Frequencies

ABSTRACT This article presents a novel experimental technique for measuring in-plane deformations and vibration modes of a rotating nonpneumatic tire subjected to obstacle impacts. The tire was mounted on a modified quarter-car test rig, which was built around one of the drums of a 500-horse power chassis dynamometer at Clemson University's International Center for Automotive Research. A series of experiments were conducted using a high-speed camera to capture the event of the rotating tire coming into contact with a cleat attached to the surface of the drum. The resulting video was processed using a two-dimensional digital image correlation algorithm to obtain in-plane radial and tangential deformation fields of the tire. The dynamic mode decomposition algorithm was implemented on the deformation fields to extract the dominant frequencies that were excited in the tire upon contact with the cleat. It was observed that the deformations and the modal frequencies estimated using this method were within a reasonable range of expected values. In general, the results indicate that the method used in this study can be a useful tool in measuring in-plane deformations of rolling tires without the need for additional sensors and wiring.

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