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Low power generation of equalized broadband CW supercontinua using a novel technique incorporating modulation instability of line broadened pump

Prakash, R and Choudhury, V and Arun, S and Supradeepa, VR (2018) Low power generation of equalized broadband CW supercontinua using a novel technique incorporating modulation instability of line broadened pump. In: Optical Components and Materials XV 2018, 29 - 31 January 2018, San Francisco.

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Official URL: https://doi.org/10.1117/12.2289495


Continuous-wave(CW) supercontinuum sources find applications in various domains such as imaging, spectroscopy, test and measurement. They are generated by pumping an optical fiber with a CW laser in the anomalous-dispersion region close to its zero-dispersion wavelength. Modulation instability(MI) sidebands are created, and further broadened and equalized by additional nonlinear processes generating the supercontinuum. This necessitates high optical powers and at lower powers, only MI sidebands can be seen without the formation of the supercontinuum. Obtaining a supercontinuum at low, easily manageable optical powers is attractive for many applications, but current techniques cannot achieve this. In this work, we propose a new mechanism for low power supercontinuum generation utilizing the modified MI gain spectrum for a line-broadened, decorrelated pump. A novel two-stage generation mechanism is demonstrated, where the first stage constituting standard telecom fiber slightly broadens the input pump linewidth. However, this process in the presence of dispersion, acts to de-correlate the different spectral components of the pump signal. When this is sent through highly nonlinear fiber near its zero-dispersion wavelength, the shape of the MI gain spectrum is modified, and this process naturally results in the generation of a broadband, equalized supercontinuum source at much lower powers than possible using conventional single stage spectral broadening. Here, we demonstrate a ∼0.5W supercontinuum source pumped using a ∼4W Erbium-Ytterbium co-doped fiber laser with a bandwidth spanning from 1300nm to 2000nm. We also demonstrate an interesting behaviour of this technique of relative insensitivity to the pump wavelength vis-a-vis zero-dispersion wavelength of the fiber.

Item Type: Conference Paper
Publication: Proceedings of SPIE - The International Society for Optical Engineering
Additional Information: The copyright for this article belongs to the SPIE.
Keywords: Continuous wave lasers; Dispersion (waves); Dispersions; Equalizers; Fiber lasers; Modulation; Optical fibers; Pumping (laser), Continuous Wave; Erbium-ytterbium co-doped fiber lasers; Highly nonlinear fibers; Linewidth broadening; Modulation instabilities; Super continuum, Supercontinuum generation
Department/Centre: Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 26 Aug 2022 06:19
Last Modified: 26 Aug 2022 06:19
URI: https://eprints.iisc.ac.in/id/eprint/76063

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