We have improved the two-wave coupling amplification and the signal-to-noise ratio of an amplified signal with photorefractive cerium-doped potassium sodium strontium barium niobate (Ce:KNSBN) by employing optimum polarization orientation of the pump beam while the signal beam retains extraordinary polarization. The optimum polarization angle of the pump beam was found experimentally to be 30 degrees with respect to the extraordinary polarization direction in a symmetrically incident system. Nearly 1.9-times enhancement of the gain and nearly 3-times enhancement of the signal-to-noise ratio were achieved at a signal-to-pump beam intensity ratio of 1:40. At a beam intensity ratio of 1:2000, a two-wave coupling gain of nearly 500 was obtained, which is much higher than the gain previously reported. Modified coupled-wave equations that involve beam fanning with certain assumptions concerning the fanning parameters were used. The numerical solution is in good agreement with the experimental data. The results are compared with those obtained with a 45 degrees -cut BaTiO(3) crystal.
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http://dx.doi.org/10.1364/ao.40.003359 | DOI Listing |
Two-wave mixing between forward- and backward-propagating signal light has recently been observed in frequency-modulated single-frequency fiber laser systems. The phenomenon is a potential limiting factor for power scaling of such frequency-tunable lasers. In this contribution, we derive a perturbative coupled-mode theory for two signals that counter-propagate in an Yb-doped fiber with a constant frequency detuning.
View Article and Find Full Text PDFJ Marital Fam Ther
January 2025
Department of Educational Psychology, Achva Academic College, The Faculty of Psychology and Social and Human Sciences, Shikmim, Israel.
This study explores whether marital quality mediates the effects of a parenting intervention on preschoolers' conduct problems and effortful control. Using data from 209 children in a two-wave randomized controlled trial of the Hitkashrut program, participants were assigned to either a 14-session co-parent training group or a minimal intervention control group. Intent-to-treat analysis revealed that improvements in marital quality significantly mediated the intervention's impact on both conduct problems and effortful control.
View Article and Find Full Text PDFCommun Earth Environ
September 2024
Faculty of Psychology, University of Basel, Basel, Switzerland.
The energy crisis reshaped energy politics, resulted in energy price surges, increased energy capacity, and large-scale energy-saving campaigns. While an energy demand reduction was observed in Europe, little is known about how the crisis impacted citizens' climate-relevant judgment and decisions. Here we report a preregistered two-wave cross-national study ( = 1040) spanning the winter of 2022/2023 to investigate how support for renewable energy policies, energy literacy, and energy-efficient product choices developed as this crisis unfolded.
View Article and Find Full Text PDFThis paper presents a theoretical and experimental characterization of an instability phenomenon observed in single-frequency fiber amplifiers when the frequency of the seed laser is modulated. The instability manifests itself as fluctuating elastic back-reflections that occur only when the frequency is decreasing with time. The theory is a generalization of a coupled-mode model developed for a single-frequency fiber amplifier back-seeded with a constant frequency shift relative to the main signal.
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