Promotionsvortrag Physik: „Noise Scaling in Coherent Beam Combination“

Ankündigung des Promotionsvortrags von: Herrn Sourav Chatterjee

State-of-the-art technology offers quantum-noise-limited laser power only up to a few hundred Watts. This in turn limits the achievable sensitivity in quantum metrology and the performance of coherent parametric processes. These requirements have created an exigency of producing higher output powers with an excellent beam quality. However, the onset of transverse mode in-stabilities in fibre lasers, restricts power scaling beyond a certain threshold, with fibre amplifiers. Coherent beam combination (CBC) serves as a technique to scale laser power beyond the phys-ical limits of optical amplifiers. In this technique, multiple independent noisy beams can be com-bined via constructive interference in a cascade of beam splitters, to generate a bright output beam with a very low noise profile. The noise variance of the final output beam then crucially depends upon the relative phase stability of the intermediate beams at each combination. In this work, we analyse the dependence of the output noise variance in CBC to the correlation in noise among the input beams. More particularly, by coherently combining two noisy beams on an inter-ferometer, we individually study the contribution of amplitude and phase noises among the input beams at the combined output. Interestingly, beyond the interferometric locking bandwidth, our results confirm a reduction in both amplitude and phase noise scaling at the combined output, in coherent combination of uncorrelated noisy input beams. This effect can be suitably exploited to generate brightest beams in CBC with (nearly) quantum-limited noise footprints.

(Vortrag auf Englisch)

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