ELOS 2022

Sergey Kobtsev

Sergey Kobtsev, Speaker at Optics Conferences 2022
Novosibirsk State University, Russian Federation
Title : Incoherent laser radiation

Abstract:

Incoherent laser radiation may be in demand among a variety applications where high directivity and brightness of radiation could be advantageously combined with the absence of speckle patterns conventional for laser radiation. Such patterns arise as a consequence of relatively high coherence of laser radiation and generally play a negative role in many applications. Interference of the incident and reflected beams produces a typical irregular (non-uniform) distribution of the optical electromagnetic field, which is an undesirable phenomenon in many applications.

A great number of publications are dedicated to reduction of the speckle effects. However, all these deal specifically with minimisation of the effect and not with elimination of it altogether. The present research takes up for the first time the possibility of a new type of radiation source, in which salient features of conventional laser radiation (high directivity and brightness) may be accompanied by low coherence. Sources of such unusual radiation may be based on noise-like pulses [1] that consist of large numbers of sub-pulses with varying amplitude and duration, chaotically positioned within the envelope of a noise-like pulse [2]. Almost random structure of such a pulse must result in minimal (or absence of) interference of electromagnetic field between different parts of the pulse (e.g. between its front and rear portions). Thus, minimal or no speckle pattern should be observable.

The present report considers aspects of practical implementation of an incoherent laser relying on noise-like pulses. Discussed are the most promising cavity configurations and possibilities of adjustable degree of coherence of the output radiation. Further on, the potential problems and bottle-necks of the new type of radiation source are analysed, as is its applicability in specific tasks. The likely period of time necessary for development of commercial incoherent lasers is estimated.

1. M. Horowitz, Y. Barad, Y. Silberberg, Noiselike pulses with a broadband spectrum generated from an Erbium-doped fiber laser, Opt. Lett., v. 22, 799-801(1997). https://doi.org/10.1364/OL.22.000799

2. Y. Jeong, L.Vazquez-Zuniga, S. Lee, Y. Kwon, On the formation of noise-like pulses in fiber ring cavity configurations, Opt. Fiber Technol., v. 20, 575-592 (2014). https://doi.org/10.1016/j.yofte.2014.07.004 

What will audience learn from your presentation?

  • The report provides knowledge needed to develop an incoherent laser
  • Development of a radically new radiation source (low-coherence or incoherent laser) stands to disrupt significantly the application areas of laser radiation
  • Development of incoherent laser will enable solutions to long-standing problems of many applications (laser TV, material processing, etc.) related to speckle interference of laser radiation

Biography:

S. Kobtsev received the joint B.S./M.S. degree in physics (quantum optics) from Novosibirsk State University, Novosibirsk, Russia, in 1982, and the Ph.D. and D.Sc. degrees in optics in 1992 and 2010, respectively. He is currently the Head of the Division of Laser Physics and Innovative Technologies, Novosibirsk State University. His research interests include fiber and nonlinear optics, tunable laser systems, and hi-tech photonics research and development. Prof. Kobtsev is a Member of the SPIE and APS, and a Senior Member of the OSA. He was honored with the OSA's Outstanding Reviewer Recognition in 2015.

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