gbghjghj.jpg

Dr. Junaid Masud Laskar

Ph.D. (IGCAR, Kalpakkam)

Assistant Professor (Research)

Soft Matter Photonics Research Group

Welecome to the Photonics & Soft Matter Physics Research Laboratory !

Open position: We are currently looking for a Junior Research Fellow (JRF) leading to PhD degree to pursue doctoral reserach in at the interface of reserach areas "Active soft matter physics" & "Tunable photonics" (Experimental) funded by SRMIST, Chennai.(Application deadline- November 10, 2018, for details please see the "Opportunities & contact" tab)

 

Our research interests: Our reserach laboratory focuses on pursuing research at the interface of photonics, soft matter physics, nanophysics, optical engineering, optics, ultrafast optics and optical technique development. We investigare light-matter interaction, structural transition dynamics, crystallization, particle contact force distribution and mechanics of soft matters (magnetic nanofluid, magnetic emulsion, colloidal gel and granular matter), particularly their interaction with external stimuli (field, stress etc.) at different length scales, using existing experimental techniques (mainly optical) and also by developing new techniques, which also includes the design of optical lens systems (microscope objective lens etc.).

Short profile of Dr. Junaid: Dr. Junaid has been working as an Assistant Professor (research) in SRM Research Institute and Department of Physics and Nanotechnology, SRM Institute of Science and Technology (formerly known as SRM University) since September 2016. He has developed a light scattering technique to study the structural transitions in magnetic field polarizable soft matters, during his doctoral (Ph.D.) research at Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, India. During his postdoctoral tenure at Max Planck Institute for Polymer Research, Mainz, Germany, he has worked on the “determination of 3D structural topological origin of elasticity in colloidal gel under compressive strain”. During postdoctoral research at Max Planck Institute for Dynamics and Self-Organization, Goettingen, Germany, he has designed and developed a stress resolving two photon fluorescence microscope to measure 3D contact force distribution in hard, frictional granular packing of ruby spheres.

Educational Qualification:

·         Ph.D. , Physics, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam & University of Madras, Chennai, India, 2013

·         M.Sc., Physics, Tezpur University, Tezpur, Assam, India, 2005

·         B.Sc., Physics, Gauhati University, Guwahati, Assam, India, 2003

Professional Experience:

·       Assistant Professor (Research), Department of Physics & Nanotechnology, SRM Research Institute, SRM Institute of Science and Technology (SRMIST),          Kattankulathur, Tamil Nadu, India, September 2016- till date.

·         Visiting Scientist, Max Planck Institute for Dynamics and Self-Organization, Goettingen, Germany, September 2017- March 2018.

·         Postdoctoral Researcher, Max Planck Institute for Dynamics and Self-Organization, Goettingen, Germany, December 2012- August 2016.

·         Postdoctoral Fellow, Max Planck Institute for Polymer Research, Mainz, Germany, December 2011- November 2012.


  • Stimuli responsive tunable soft matter photonics for the development of wavelength tunable random laser.
  • Active dynamics of colloidal particles under the combined influence of magnetic field and space-time varying random potential- for application of optical manipulation, e.g. sorting.
  • Effect of acoustic waves on the 3D contact force distributions in granular media as a model system to understand the effect of seismic waves in seismogenic granular fault of earth crust.

Group leader:  Dr. Junaid Masud Laskar

Graduate students:

  • Kalaiarasan M        [M.E. (Applied Electronics)], 
  • Hardepinder Singh [ Integrated M.Sc. (Physics)]

Undergraduate students:

  • Vijay Shekhawat [B.Tech. (Nanotechnology)]
  • Saket [B.Tech. (Nanotechnology)]
  • Abhijit  [B.Sc. (Physics)]
  • “Path length tunable light-matter interaction in magnetic nanofluid based field-induced photonic crystal-glass structure”, J. M. Laskar, B. Raj and J. Philip, New J. Phys. 18, 103037 (2016). Video abstract:  https://www.youtube.com/watch?v=cPQCCzMU2yc
  • “High refractive index immersion liquid for super-resolution 3D imaging using sapphire-based aNAIL optics”, J. M. Laskar, P. S. Kumar, S. Herminghaus, K. E. Daniels, and M. Schröter, Appl. Opt. 55, 3165 (2016)
  • "The effect of suspended Fe3O4 nanoparticle size on magneto-optical Properties of ferrofluids”, S. Brojabasi, T.Muthukumaran,  J. M. Laskar, and J. Philip, Opt. Commun. 336, 278 (2015).
  • “Optical Properties and Applications of Ferrofluids- A review”, J. Philip   and J. M. Laskar, J. of Nanofluids, 1, 3 (2012)
  • “Comparison of light scattering from self -assembled array of nanoparticle chains with cylinders”, J. M. Laskar, S. Brojabasi, B. Raj, and J. Philip, Opt. Commun. 285, 1242 (2012).
  • “Enhanced transmission with tunable Fano-like profile in magnetic nanofluids”, J. M. Laskar, B. Raj, and J. Philip,   Phys. Rev. E 84, 051403 (2011).
  • “Experimental investigation of magnetic-field-induced aggregation kinetics in nonaqueous ferrofluids”, J. M. Laskar, J. Philip, and B. Raj,   Phys. Rev. E 82, 021402 (2010).
  • “Experimental evidence for reversible zippering of chains in magnetic nanofluids under external magnetic fields”, J. M. Laskar, J. Philip, and B. Raj, Phys. Rev. E 80, 041401 (2009).
  • “Observation of discrete localized surface plasmon (LSP) states in isolated nanoscaled Ag-particles synthesized via photochemical reduction route”, J.M.Laskar, D. Mohanta and A. Choudhury, Eur. Phys. J. Appl. Phys. 46, 20602 ( 2009).
  • “Light scattering in a magnetically polarizable nanoparticle suspension”, J. M. Laskar, J. Philip, and B. Raj, Phys. Rev. E 78, 031404 (2008).
  • “Magnetic field induced extinction of light in a  suspension of  Fe3O4 nanoparticles”, J. Philip, J. M. Laskar and B. Raj,  Appl. Phys. Letts. 92, 221911 (2008).
  • “Measurement of thermal diffusivity of solids using continuous heat source and infrared thermography”, J.M.Laskar, S. Bagavathiappan, M. Sardar, T. Jayakumar, J. Philip and B. Raj,  Materials Letters 62, 2740 (2008). 

 

 

B. Tech (Material Science)

B.Sc. (Laser Technology)

Opportunities:

Interested researchers and students with motivation to explore rich physics in the frontier research areas- photonics and soft matter physics are welcome to contact us for the following positions --

 

A) Postdoc position: Interested candidates should feel free to contact us

 

B)

1) DST, SERB, Govt. of India funded Phd/ JRF positions: 

PhD  Project title: External stimulus tunable random lasing based on magnetic soft matter

Background of the project: The idea of investigating and harnessing the rich physics arising from scattering due to unavoidable structural disorder present in any photonic material and the quest for lasers with reduced components leading to size miniaturization, low fabrication cost and tunability by external stimuli have resulted in the surge of interest in random laser (scattering medium with optical amplification or gain) research during the last two decades. Unlike a conventional laser, a random laser does not have any optical cavity, instead, the optical feedback comes from light scattering in a disordered media, and the interference of the scattered light gives rise to resonant modes at particular frequencies. Random lasers have many unique and useful characteristics, including very low spatial and/or temporal coherence; many modes can lase simultaneously with uncorrelated phases over a very broad frequency range. Besides making tremendous progress in understanding random lasing, in different disordered media, in combination with other physical phenomena - optical amplification, scattering, nonlinearity, and/or localization, external stimulus tunability of random lasing characteristics – lasing threshold, modes (frequency) - is yet to be achieved. 

Goal of the project: Our goal is to achieve tunable random lasing on using magnetic field tunable soft matter systems as tunable random media with gain, where both the degree of order/disorder and the scattering strength can be easily controlled by applied field strength.

Essential qualification: M.Sc. (Physics/Photonics/Applied Physics/Material Science) or M.Tech. (Photonics/ Applied Optics/ Laser Technology/ Fiber Optics and Lightwave Engineering/ Opto-Electronics and Optical Communication/ Optics & Optoelectronics) securing minimum first class or equivalent CGPA.

Desirable: Stronng motivation to explore rich physics in the research areas - photonics/optics and soft matter physics.

Development opportunities: Selected candidate will have the opportunity to work in interdisciplinary field including tunable light-matter interaction, sample synthesis, lasers (pulsed and continuous wave), fiber optics spectrometer , spatial light modulator, Z scan measurement of nonlinear properties, interferometer development, instrument (optical and magnetic field setup) interfacing with LabVIEW and data analysis. Candidates will also have the opportunity to pursue research within the framework of national (TIFR, Mumbai, IGCAR, Kalpakkam etc.) and international (Max Planck Institute-DS, Goettingen, Germany,  NCSU, Raleigh, USA etc.) collaboration, present research at national and international conferences.

Age limit: 28 years or below till last date of application.

Fellowship: For NET qualified candidates the fellowship is Rs 25,000  per month. 

Fellowship Tenure: 3 years.

Registration for Ph.D.: Selected candidate shall register for full time Ph.D. program at SRM Institute of Science and Technology, Kattankulathur, Chennai-603203.

Application procedure: Eligible candidates are requested to send their CV via e-mail to the Principal Investigator Dr. Junaid Masud Laskar (e-mail: jmlaskar@gmail.com, junaidmasud.b@ktr.srmist.edu.in), Assistant Professor (research), Research Institute, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Chennai 603203, Tamil Nadu.

Subject of the email should be “Application for JRF position in tunable random laser”.

Application deadline: November 10, 2018.

 

 

2) SRMIST funded PhD/JRF position: Two open positions

Ph.D project title: Active dynamics of magnetic colloidal particles (cooperative magnetophoresis) under magnetic and random light field

Background: Magnetophoresis is the controlled motion of magnetic particles dispersed in a fluid medium by the application of magnetic field gradient. The net magnetic force acting on a magnetic colloidal particle is a function of the difference of the particle’s magnetization and the magnetization of the surrounding fluid. This allows for the manipulation of both magnetic and non-magnetic particles by tuning this magnetization mismatch. However, the process becomes complex on increasing the number dispersed magnetic entities (particles, oil droplets etc.) in the carrier fluid.

 

Magnetophoresis plays crucial role in biotechnological applications including protein isolation, cell separation, drug delivery, and biocatalysis[1]. Other interesting applications involve the capture and extraction of pollutants[2] and the processing of bacteria for biofuel applications[3]. Companies are offering superparamagnetic microspheres to use in combination with magnetophoretic systems as alternatives to conventional chromatography resins in automated high throughput protocols replacing centrifugation, organic solvents and filtration.

 

Under uniform field gradient in ferrofluid, also known as magnetic nanofluid (a stable dispersion of magnetic nanoparticles in a carrier liquid), the magnetophoretic velocities of the particles are observed to be very slow initially; but large chain-like aggregates are rapidly formed. These aggregates move rapidly and lateral aggregation among the chains form even larger aggregates, which move at a faster velocity; a process termed as cooperative magnetophoresis[4]. Although it is understood that concentration plays a key role on the cooperative magnetophoresis; there are still open questions, especially regarding the dependence of the magnetophoretic velocity on the magnetic field gradient and the stabilization method of the particles.

We have observed that the ramp rate of applied field dictates the kinetics of aggregation process in ferrofluid, depending on the competition between the magnetic force (Fmag) and viscous force (Fdrag)[5].

Therefore, our first goal (1) is to perform ramp rate dependent applied field gradient cooperative magnetophoresis study in oil in water ferrofluid emulsion, where larger size (d ~ 200 nm) of the oil droplets containing the superparamagnetic nanoparticles will allow us to observe significantly greater magnetic response than ferrofluid (d ~ 8 nm), as Fmag ∝ d3 and Fdrag ∝ d; using optical microscope. 

Moreover, colloidal particles immersed in a dynamic speckle pattern experience an optical force that fluctuates both in space and time. The resulting dynamics presents many interesting analogies with a broad class of non-equilibrium systems like: active colloids (co-operative magnetophoresis), self-propelled microorganisms, transport in dynamical intracellular environments[6]. Various phenomena rely on particles performing stochastic motion in random potentials. Examples range from the nanoscopic world of molecules undergoing anomalous diffusion within the cytoplasm of a cell to the Brownian motion of stars within galaxies[7].

 

Another example of this kind of phenomena is given by the motion of a Brownian particle in a random optical potential generated by a light speckle pattern[8], i.e., the random light field resulting from complex light scattering in optically complex media, such as scattering medium of magnetic nanofluid, biological tissues, turbid liquids and rough surfaces. This is particularly suited to work as a model system because its parameters [e.g. particle size (field dependent changing nanoparticle aggregate/scatterer size and material, illumination light] are easily controllable and its dynamics are easily accessible by standard optical microscopy techniques. Earlier experimental works showed the possibility of trapping particles in high intensity speckle light fields, the simplest optical manipulation task, and the emergence of super-diffusion in an active media constituted by a dense solution of microparticles that generates a time-varying speckle field. However, apart from these previous studies, there is little understanding of the interaction of Brownian motion with random light potentials and the intrinsic randomness of speckle patterns is largely considered a nuisance to be minimized for most purposes, e.g., in optical manipulation.

 

Our second goal (2) is to study and control the transport of magnetic colloidal particles by manipulating the interplay among magnetic force, viscous force and space-time varying optical force, which will be applied by using laser speckle pattern[8].

 

 

References:

 

  1. C. T. Yavuz et al., Chem. Eng. Sci. 64, 2510 (2009).
  2. C. T. Yavuz et al., Science 314, 964 (2006). [3]     J. K. Lim et al., Small 8, 1683 (2012).
  1. J. Faraudo, J. S. Andreu, and J. Camacho, Soft Matter 9, 6654 (2013).
  2. J. M. Laskar, J. Philip, and B. Raj, Phys. Rev. E 82, 021402 (2010).
  3. S. Bianchi et al., Sci. Rep 6, 27681 (2016).
  4. G. Volpe, G. Volpe, and S. Gigan, Sci. Rep              4, 3936 (2014).
  5. J. M. Laskar, B. Raj, and J. Philip., New J. Phys 18, 103037 (2016).

 

Application Procedure: Interested candidates should apply online through the weblink

 https://www.srmist.edu.in/  ...  All Programs 2018 -- Apply Now

or

https://applications.srmist.edu.in/

For details, the candidate should contact us.

 

C) M.Sc. project: One project is available

 

D) B.Tech. project: One project is available

 

Contact details:
Dr. Junaid Masud Laskar
Assistant Professor (Research)
Room: R-34, 13th Floor, University Building,
Department of Physics & Nanotechnology/ Research Institute
SRM Institute of Science and Technology
Kattankulathur - 603203
Tamil Nadu, India
Tel (Off): +91-44-27417922
Mob:   +91-6382542022
Email:junaidmb@srmist.edu.in