Signal Propagation Over Polarization-Maintaining Fibers: Problem and Solutions

Penninckx, D.; Beck, N.; Gleyze, Jean-François; Videau, L.

doi:10.1109/jlt.2006.884189

Cited by 42 publications

(34 citation statements)

References 15 publications

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“…When using waveguide phase modulator and PM fiber, if the two polarizations in the PM fiber are excited and subsequently mixed by imperfect polarization control, spectral nonuniformity owing to etalon-like effect will result. Even a vary small amount of depolarization (typically ~100:1) can lead to vary large AM [11] . Fig.…”

Section: Experimental Investigationmentioning

confidence: 99%

“…In solid state laser drivers, it is still an important issue to output smooth waveform, as waveform is the basis of safe amplification. Furthermore, amplitude modulation (AM) can destroy power balance, prevent ignition of target and amplify instabilities of the plasma [9][10][11][12] . A purely frequencymodulated (FM) beam exhibits no amplitude modulation.…”

Section: Introductionmentioning

confidence: 99%

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Research of beam smoothing technology on the technical integration line

Zhang

et al. 2013

SPIE Proceedings

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This paper is focused on the research of SSD and CPP carried out on TIL. A bulk phase modulator with 9.2-GHz modulation frequency is adopted in SSD. The output spectrum of the phase modulator is stable and the residual amplitude modulation is small. FM-to-AM effect caused by free-space propagation after using smoothing by spectral dispersion is theoretically and experimentally studied. Results indicate inserting a dispersion grating in places with larger beam aperture alleviates the FM-to-AM effect, suggesting minimizing free-space propagation and adopting image relay. Experiments indicate when the number of color cycles (N c ) adopts 1, imposing of SSD with 4.26 times diffraction limit (TDL) did not lead to pinhole closure in the spatial filters of the preamplifier with 20 TDL and main amplifier with 26 TDL. Experimental results also indicate SSD didn't influence the load capacity of the laser facility. The contrast of the 440-μm diameter focal spot with 95% energy included using SSD and CPP drops to 0.47, comparing to 1.71 not using SSD and CPP. When the pulse width of the third harmonic wave is 1 ns and the energy is 1115 J, no damage is found in CPP and other final optics. The experiments solves some key technical problems using SSD and CPP on high-power laser facilities, and provides a flexible platform for the laser-plasma interaction experiments.

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Section: Experimental Investigationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Research of beam smoothing technology on the technical integration line

Zhang

et al. 2013

SPIE Proceedings

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“…(1), it is a ratio between maximum power (P max ) and minimum power (P min ) both through a polarizer [1]. Typically, the acceptable PER is above 20 dB [2]- [3]. …”

Section: Introductionmentioning

confidence: 99%

Temperature dependency of Polarization Extinction Ratio in Polarization Maintaining Fiber with LC/UPC connectors

Thongdaeng¹,

Worasucheep

2016

2016 Photonics North (PN)

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This paper reports the temperature dependency of Polarization Extinction Ratio (PER) in Polarization Maintaining Fiber (PMF) with LC/UPC connectors. Ten LC/UPC PMF patchcords were PER measured under 3 testing conditions: A, B and C. Test A, patchcords were coiled on hot plate for 5 loops with 3-cm inner diameter and 4-cm outer diameter. The hot plate's temperature was increased from 25°C to 75°C and decreased back to 25°C at a step of 5°C. Test B, patchcords were coiled around hot rod with 3-cm in diameter for 5 loops. The hot rod's temperature was set in the same manner as Test A between 25°C to 100°C. In Test C, patchcords were uncoiled and left at room temperature while being PER measured for 15 minutes. From the sampled PER plots, small variations occur mainly at temperature transitions. The Standard Deviations (SDs) of PER confirm that their averages in Test A and B are nearly the same (0.30 -0.35), but larger than the average SDs in Test C (0.17 and 0.21). However, when only the PERs below 35 dB (according to OZ Optics ER-100-IR specification) at 75°C in Test A and B are computed, their average SDs reduce to 0.08 and 0.06 respectively. Hence, the hot rod at constant 75°C is chosen for future PER measurement because of its stable results in shortest time and simplified setup.

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“…Here, α ranges from 0% to 200% and is ideally equal to 0. Considering a transmission system with a following intensity filtering function [9] H(fwhere f c is the central frequency of the filter and σ f is the filtering coefficient. Because sinusoidal phase modulation is always adopted, the modulated optical field can be given by a 0 (t) = exp[iδ sin(2πf m t)],…”

mentioning

confidence: 99%

“…Here, α ranges from 0% to 200% and is ideally equal to 0. Considering a transmission system with a following intensity filtering function [9] H(f…”

mentioning

confidence: 99%

Analysis on FM-to-AM conversion induced by spatial filter in a high-power laser system

Hujie¹,

Zhou²,

Jiang³

et al. 2012

中国光学快报

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In order to avoid stimulated Brillouin scattering and smooth the final focal spot that reaches the D-T capsule, spectral broadening is essential. However, the modulation of spectral structure might result in frequency-to-amplitude modulation (FM-to-AM) conversion. The spatial filter pinhole is used to cut off the high-frequency transmission laser, and to ensure the desired pass. Improper parameter of pinhole would lead a negative impact. Using the spatial filter pinhole, we analyze the characteristic of intensity modulation using several pinholes of improper parameters. We then compare these results with the intensity modulation obtained from an experiment. Experimental diagnosis and design of an appropriate pinhole parameter would be highly beneficial to the field of high-power lasers.OCIS codes: 050.5080, 070.2615050.5080, 070. , 220.4840, 300.1030 To ensure the stability of implosion experiment in ICF, a high-quality temporal pulse shape laser is necessary. Some problems, such as how to control temporal profile and frequency-to-amplitude modulation (FMto-AM) conversion [1] , must be studied in detail. In the high-power laser system, the laser spectrum is broadened for two reasons to avoid stimulated Brillouin scattering [2] (SBS) and to "smooth" the final focal spot that reaches the D-T capsule. First, without spectral broadening, spectral power density of ignition laser pulses would exceed the transverse Brillouin threshold in optics at the end of the amplifier chain, thereby severely damaging the optics components. Spectral broadening spreads energy to different wavelengths to reduce the spectral power density maximum level below the SBS threshold. Second, nonuniformities in the laser irradiation may seed the Rayleigh-Taylor hydrodynamic instability, which degrades target performance. Therefore, high spatial homogeneity [3] is desired for focal spots. In fact, the focal spot of the laser beam is shaped by a phase plate and appears as a speckle pattern with hot spots. The intensity is time-averaged through spectral broadening and a dispersion system (grating) that moves the hot spots during the pulse. This scheme is called smoothing by spectral dispersion [4] . Although the required spectral broadening adopted by the aforementioned techniques are generated by a pure phase modulation that would not impact the spatial intensity distribution directly, some optical components, including fibers, amplifier media, and spatial filters, could slightly affect the spectrum. The consequences of such filters are a partial conversion of FM into intensity modulation called FM-to-AM conversion. Hocquet and Yang analyzed the factors resulting in FM-to-AM conversion in detail, including group velocity dispersion, gain narrowing, frequency doubling, grating, and so on [5−7] . Unfortunately, to the best of our knowledge, the conversation induced by the sideband cutoff of a spatial filter pinhole has not yet been discussed. Spatial filter is a necessary element in high-power laser systems, undertaking beam expanding, image tran...

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Signal Propagation Over Polarization-Maintaining Fibers: Problem and Solutions

Cited by 42 publications

References 15 publications

Research of beam smoothing technology on the technical integration line

Research of beam smoothing technology on the technical integration line

Temperature dependency of Polarization Extinction Ratio in Polarization Maintaining Fiber with LC/UPC connectors

Analysis on FM-to-AM conversion induced by spatial filter in a high-power laser system

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