OSC Colloquium: Dr. Vladimir Pervak

    Date: 
    Thursday, March 14, 2019 - 3:30pm - 5:00pm
    Location: 
    Meinel 307
    Address: 

    1630 E. University Blvd.

    3rd Floor Lobby area

    Registration: 

    Open to campus and public.

    Description: 

    Speaker: Dr. Vladimir Pervak 

    Topic: Advanced Multilayer Coatings for Femtosecond and Attosecond Physics

    Host: Mohammed Hassan

    Visit our website for future lecture dates and speaker information: http://www.optics.arizona.edu/news-events/events/colloquium For a list of our archived lectures: http://www.optics.arizona.edu/news-events/events/colloquium/archive

    Abstract(s): 

    The goal of generating short laser pulses down to the limit set by a single wave cycle of light has been pursued ever since the invention of lasers. Laser pulses consisted of only a small number of wave cycles allow more efficient exploitation of nonlinear optical effects with implications as striking as the generation of single sub-femtosecond light pulses. The controlled superposition of light frequencies extending over more than one octave together with carrier-envelope phase control pave the way for shaping the sub-cycle evolution of light fields in laser pulses.

    Dr. V. Pervak will provide an overview of dispersive multilayer optics. Dispersive mirror (DM) offers high reflectivity and controlled group delay dispersion (GDD) over some 1.5 octaves spanning ultraviolet to near infrared frequencies. Nowadays, we cannot imagine ultrashort pulses being obtained without dispersive multilayer optics. A DM is a dispersive optical interference coating usually designed by optimizing the initial multilayer design. A DM is characterized by a certain value of the group delay (GD) or GDD. GD is the first derivative of the phase shift with respect to the angular frequency:

     

    where φis the phase-shift obtained on reflection or transmission, ωis the angular frequency. GDD is the second derivative of the phase shift with respect to the angular frequency or is first derivative of the GD:

     

    The short pulse penetrating through dispersive medium becomes longer due to the introduced GD, as illustrated in Fig. 1. By introducing an inverse GD with a DM, the pulse can be compressed to its original pulse duration. In general, the GDD of mirror should compensate material dispersion (through which the initially short pulse passes) or the (nonlinear) chirp of the pulse so that the residual dispersion oscillations are acceptably small in all of the relevant spectral range.

    The DM is one of the key elements of most ultrafast (femtosecond) lasers. Whilst being able to provide control of phase over unprecedented bandwidths and high efficiency, the DM technology suffers from unavoidable spectral oscillations of the phase. Reflection from the top layer of a multilayer structure introduces oscillations to the GDD curve due to interference between waves reflected from the top layer and waves which have penetrated and have been reflected from deeper.  These oscillations may adversely affect the quality of the femtosecond laser pulses which are being controlled with DMs. Usually during design optimization the residual fluctuations drop down to a low level. The GDD oscillations can broaden the pulse and lead to energy transfer from the initial single pulse to satellites. The period of the ripples in the spectral domain determines the position of the satellite in the temporal domain, and the amplitude of these oscillations determines the amount of energy which is transferred to the satellites.

           The manufacture of DMs can be as challenging as their design, as DMs are extremely sensitive to a discrepancy in layer thickness. In most cases, magnetron-sputtering and ion-sputtering technologies provide sufficient precision of the layer thickness control. Modern sputtering technology can provide sub-nm precision in controlling the layer thickness. Some applications such as highly dispersive mirrors require angstrom precision.  The extreme sensitivity of the DM can then be overcome by applying a special, robust design algorithm.

            The result of the 20-year evolution of the design and fabrication of dispersive multilayers now allows the development of structures with low loss and high dispersion over a wide spectral range, and permits compression down to the theoretical limit of the pulse duration.

    Speaker Bio(s): 

    Education:

    2004 – 2006  Ph.D. in Physics,  Max-Planck-Instiute of Quantum Optics, Garching, Germany and Kiev National Taras Schevchenko University, Kiev, Ukraine

    2002 – 2004    Diploma of Magister with honor of laser and optoelctronics, Kiev National Taras Schevchenko University, optical division Diploma’s theme is “Synthesis and properties of three components periodical broadband interference filters”

    1998 – 2002    Diploma of Bachelor with honor of laser and optoelctronics, Kiev National Taras Schevchenko University, optical division

    Positions Held:

    2009 - Today   Head of coating department in Ultrafast Innovations GmbH, Garching, Germany

    2007 - Today  Group Leader in Laboratory for Attosecond and High-Field Physics headed by Prof. Krausz, at Ludwig Maximilians University and Max-Plank-Institute of Quantum Optics, Garching, Germany

    2007 - Today   Chief of MAP of Service Center (coating facility) at Ludwig Maximilians University,Garching, Germany

    2004 - 2007     Ph.D. student Max-Plank-Institute of Quantum Optics, Garching, Germany

    2003 - 2004     Engineer (division of experimental physics, physics department Kiev National Taras Schevchenko University, Ukraine)

    1998 - 1999     Engineer in Institute of Semiconductors Physics, Kiev, Ukraine

    Awards:

    • Winner of “Detschland land der Ideen”, as chief of Service center honored „Ausgewählter Ort im Land der Ideen“ (2011)
    • Outstanding Designer Award for second Prize High-Performance Solar-Selective Coating Design Submission to the OIC 2010 Design Contest (2010)
    • Outstanding Designer Award for second Prize Near and Mid-IR Fabry-Perot Etalon Design Submission to the OIC 2010 Design Contest (2010)
    • Outstanding Designer Award for third Prize Non-Polarizing Beamsplitter Design Submission to the OIC 2007 Design Contest (2007)
    • Outstanding Designer Award for third Prize Triple Bandpass Design Submission to the OIC 2007 Design Contest (2007)
    • Award of National Academy of Science of Ukraine for the works "The spectral properties and using two-component interference systems" (2001)
    • Best presentation on SPO-2001 like junior scientist, “Spectral properties of the band interference filters with increased level of background suppression” (2001)

    Current interest:

    • Development of multilayer dispersive coatings in VUV-UV-Vis-IR-NIR-MIR ranges;
    • Mirror characterization (reflectivity, dispersion (GD, GDD), transmission, surface quality, damage threshold, scattering, absorption, losses) and reverse engineering;
    • Generation of high energy and extremely short femtosecond pulses;

    Scientific accomplishments:

    • First demonstration of broadest dispersive mirrors (spanning 1.5 octaves in wavelength ranges: 400-1200 nm and 300-900 nm), which are able to compress pulses down to sub-3 fs [V. Pervak et al Opt. Lett. 32, 1183 (2007), V. Pervak et al Appl. Phys. 87, 5 (2007)];
    • First demonstration of pure highly dispersive mirrors (HDM) compressor. Compressing of 5 ps pulse down to sub-20 fs only with dispersive mirrors. An all dispersive-mirror compressor, being intrinsically free from nonlinear effects, spatial and angular chirps, eradicates all main hurdles of CPO and CPA-systems in reaching near bandwidth-limited compressed pulses with excellent spatial quality. [V. Pervak et al Opt. Express 16, 10220 (2008); V. Pervak et al Opt. Express 17, 19204 (2009)];
    • Invention of double angle dispersive mirrors (DADM), precision broadband dispersion control with multilayer mirrors produced in a single coating run. Inherent fluctuations of the group-delay dispersion (GDD) are suppressed by using the mirrors at two different angles of incidence. This technology allows compressing pulses below 3 fs. [V. Pervak et al Opt. Express 17, 7943 (2009), B. Alonso et al Appl. Phys. B 112, 105 (2013)];
    • First realization of optical waveform synthesis for generation of sub-circle pulse together with colleagues from group of Dr. Goulielmakis [E. Goulielmakis et al Science 317, 769 (2007), A. Wirth et al Science 334, 195  (2011),O. Razskazovskaya et al Optica 4, 129-138 (2017)];
    • First observation of non-linearity in dielectric multilayers at high intensities [ O. Razskazovskaya et al Optica 2, 803 (2015),E. Fedulova et al Opt. Express 24, 21802-21817 (2016),T. Amotchkina et al Opt. Express 25, 12675 (2017)];
    • First dispersive mirrors in NIR (2-4µm) with low OH-absorption [T. Amotchkina et al Opt. Express 25, 10234-10240 (2017), ];
    • First production of MIR (9-11.5 µm) dispersive mirror[F. Habel et al Appl. Opt. 56, C71 (2017)];
    Schedule: 

    Refreshments 3:30pm

    Lecture @ 3:45pm - 5pm