An International Research Journal

Vol 25 No 7,2016

AJP

SSN : 0971 - 3093

Vol 25, No 7, July 2016

25th Anniversary Year of AJP-2016

Accepted papers: Vol 25, No 7, 2016

Special Section on

Micro and nano-optics"

Edited by

Shanti Bhattacharya, Saulius Juodkazis and Robert Brunner

Short Note on the SERB school on Optical Metrology conducted in Tezpur University, June 2016

By Dr. Shanti Bhattacharya, Department of Electrical Engineering, IIT Madras, Chennai 600036

With inputs from Prof (Dr.) Rajpal S. Sirohi, Tezpur University

 

A SERB school on Optical Metrology was recently conducted by the Department of Physics, Tezpur University, Assam. The directors of the school were Dr. Rajpal S. Sirohi, BRLGB Chair professor, Tezpur University and Dr. Gazi A. Ahmed, Head, Department of Physics, Tezpur University. The process for conduct of the school started in 2014 and the first meeting of the Planning Committee was held on April 10, 2015. The contents of the school, the speakers and other relevant points were decided in that meeting. Approval for the meeting came in May 2015 and school ran from June 1st to June 21st, 2016.

Fig 1. Background of participants

Fig 1. Background of participants

From the applications, a committee shortlisted 50 candidates for the school, which finally had 42 participants and 20 speakers. As can be seen from fig.1, most participants were research scholars. Also, although the majority was from Assam, there was good representation from across the country, as seen in the bar chart of fig 2.

Fig 2. States from which participants attended

Fig 2. States from which participants attended

The school was conducted six days a week with lectures from 9 am till 4pm, after which there was either a two-hour lab session or a popular lecture. I had the privilege of teaching at this school on 18th June and was pleased to find the students still motivated after more than two weeks of intense classes and lab sessions. This could be attributed to the high quality of teachers and topics covered. Speakers were from several academic institutes like IIT Delhi (Kehar Singh, Chandra Shakher, P. Senthilkumaran), IIT Guwahati (Bosanta Boruah), IIT Madras (M.P.Kothiyal, A.R.Ganesan and Shanti Bhattacharya), Calcutta University (L. N. Hazra) and Tezpur University(R. S. Sirohi, Pabitra Nath, Ashok Kumar, P. Deb and Gazi Ahmad); as well as from government research labs such as IRDE, Dehradun (A. K. Gupta and Amitava Ghosh) and RRCAT, Indore (P. K. Gupta and Mahesh Kumar Swami). 

The topics within the field of Optical Metrology were diverse and ranged from sources & detectors to the Moiré phenomenon to measurements with fibre optics, MEMS, Vortex beams and metrology of biological systems, to mention just a few. 

One unique feature of this school was that students were given time to present their research work, allowing them to get valuable feedback from fellow attendees and the schools directors.

All in all, this was a well-organised and useful school that will benefit its participants in both the short and long term. 


Asian Journal of Physics                                                                                                          Vol. 25 No 7 (2016)  797-808


Spatial light modulator based Fresnel incoherent digital holography


Roy Kelner and Joseph Rosen

Department of Electrical and Computer Engineering

Ben-Gurion University of the Negev, P.O Box 653, Beer-Sheva 8410501, Israel

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The ever-going progress of spatial light modulators (SLMs) technology greatly contributes to the integration of SLM devices into digital hologram recorders. In this review paper, the role of these devices in Fresnel incoherent correlation holography (FINCH) is addressed. The evolution of FINCH in the last decade is described and discussed; emphasis is given to the SLM part in the system.

© Anita Publications. All rights reserved.

Keywords: Spatial light modulators (SLMs), Digital hologram (DHs), Computer generated holograms (CGHs)

Total Refs:59

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Asian Journal of Physics                                                                                                         Vol 25, No 7 (2016) 809-831


Graphene: A review of optical properties and photonic applications

 

M K Kavitha and Manu Jaiswal

Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India

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This article gives a brief overview of the broad-range optical response of graphene and its scope for photonic applications. The optical absorption of single-layer graphene is unique, since it is governed entirely by a fundamental constant of nature, the fine structure constant. The absence of frequency dependence or a dependence on any material properties are noteworthy characteristics. The origin of the optical properties of graphene is discussed with regard to its peculiar band structure and the massless relativistic nature of its charge carriers. Electrostatic gating is one useful knob to modulate the optical absorption, since it modifies the position of the Fermi energy in this low-dimensional material. The experimental evaluation of the optical response of graphene using spectroscopic ellipsometry is discussed in detail. Reduced graphene oxide is the defective counterpart of graphene that can be solution-processed. Its optical properties can be varied by tuning the size of sp2-rich graphene domains. The optical properties of defected graphene are discussed and the important contribution of confined two-dimensional water present in the interlayers is also highlighted. Finally, interesting photonic applications in photodetectors, non-linear optical elements and photovoltaics arising from the combination of unique electronic and optical properties of graphene and its derivatives are summarized.

Keywords: Graphene, Fine-structure constant, Electrostatic gating, Spectroscopic Ellipsometry, Non-linear optics

Total Refs: 136

Graphene: A review of optical properties and photonic applications.pdf
M K Kavitha and Manu Jaiswal

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Asian Journal of Physics                                                                                                           Vol 25, No 7 (2016) 833-844


Focused ion beam milling for the fabrication of beam-shaping spiral phase optical elements

 

Pramitha Vayalamkuzhi and Shanti Bhattacharya

Department of Electrical Engineering

Indian Institute of Technology Madras, Chennai-600 036, India

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Focused ion beam (FIB) milling is a versatile technique for direct fabrication of micro/nano optical elements with good resolution on a variety of substrates for a wide range of applications. The fabrication of fork-shaped gratings (FSGs) and spiral phase plates (SPPs) in a quartz plate using a 30 kV Ga+ ion beam is presented. Scanning electron microscopy images demonstrate the realization of fork-shaped gratings and multilevel phase plate with good structural quality. The generation of donut beam could be demonstrated by optical testing. © Anita Publications. All rights reserved.

Keywords: Diffractive optical elements (DOEs), Spiral phase plates (SPPs), Focused Ion beam lithography.

Total Refs : 23

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Focused ion beam milling for the fabrication of beam-shaping spiral phase optical elements.pdf
Pramitha Vayalamkuzhi and Shanti Bhattacharya

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Asian Journal of Physics                                                                                                            Vol 25, No 7 (2016) 845-851

 

Integrated optical position sensor for MEMS mirrors

 

S Richter, G Krampert, U Wolf, L Riedel and D Doering

Carl Zeiss AG, Corporate Research and Technology, Carl Zeiss Promenade 10, D-07743 Jena, Germany

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We report on a position sensing system for quasistatic MEMS mirrors using a point source LED imaged onto the backside of the mirror. The position signal is detected by a 4-quadrant-diode and can be used for digital closed-loop control. The resulting resolution is about 13 bit at a sampling frequency of 500 ksps. The whole detection system is miniaturized and integrated in a package enclosing the MEMS mirror, the optical beam path as well as the amplifier circuit of the 4-quadrant-diode. © Anita Publications. All rights reserved.

Keywords: MEMS, Scanning mirrors, Beam steering, closed loop control, 4-quadrant diode.

Total Refs: 8

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Asian Journal of Physics                                                                                                           Vol 25, No 7 (2016) 853-869

 

Tunable optical submicron structures based on soft matter

 

Wolfgang Mönch

Technische Hochschule Nürnberg Georg Simon Ohm, Postfach, 90121 Nürnberg, Germany

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Tunable, active, adaptive and variable optics has experienced a steep development during the last two decades. While initially in adaptive optics, the individual segments of, for example large mirror were actuated individually by mechanical means, a current trend goes towards liquid and soft optical elements. Soft matter brings along with it a wealth of effects that are new in the field of optics. This article, which is intended at the same time an introductory tutorial and a short review, describes the current status in a sub-field of tunable optics and focuses on optical elements based on submicron structures. This scope encompasses all types of diffracting elements, Bragg mirrors and filters, and photonic bandgap elements. After the introduction, we give a concise overview on the material basics and the fundamentals of the tuning effects. The following section presents an overview on the state of the field as found in scientific literature. The article closes with some concluding remarks and the references. © Anita Publications. All rights reserved.

Keywords:  Adaptive optics. Bragg mirrors, Diffracting elements

Total Refs: 98

Tunable optical submicron structures based on soft matter.pdf
Wolfgang Mönch

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Asian Journal of Physics                                                                                                            Vol 25, No 7 (2016) 871-878


Percolation threshold gold films on columnar coatings: characterisation for SERS applications

 

Armandas Balcytis1, 2, Tomas Tolenis2, Xuewen Wang1, Gediminas Seniutinanas1, Ramutis Drazdys2, Paul R Stoddart3 and Saulius Juodkazis1                                            1Centre for Micro-Photonics, Swinburne University of Technology, John St., Hawthorn, VIC 3122, Australia

2State research institute Center for Physical Sciences and Technology, Savanori¸u ave. 231, Vilnius, Lithuania, LT-02300,

3Faculty of Science, Engineering and Technology, Swinburne University of Technology, John St., Hawthorn, VIC 3122, Australia

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Percolation of gold films of ~ 15 nm thickness was controlled to achieve the largest openings during Au deposition. Gold was evaporated on 300-nm-thick films of nanostructured porous and columnar SiO2, TiO2 and MgF2 which were deposited by controlling the angle, rotation speed during film formation and ambient pressure. The gold films were tested for SERS performance using thiophenol reporter molecules which form a stable self-assembled monolayer on gold. The phase retardation of these SERS substrates was up to 5% for wavelengths in the visible spectral range, as measured by Stokes polarimetry. The SERS intensity on gold percolation films can reach ~ 103 counts/(mW.s) for tight focusing in air, while back-side excitation through the substrate has shown the presence of an additional SERS enhancement via the Fresnel near-field mechanism. © Anita Publications. All rights reserved.

Keywords: 3D coatings, Raman sensors, surface enhanced Raman scattering

Total Refs: 15

Percolation threshold gold films on columnar coatings characterisation for SERS applications.pdf
Armandas Balčytis, Tomas Tolenis, Xuewen Wang, Gediminas Seniutinas, Ramutis Drazdys, Paul R Stoddart and Saulius Juodkazis

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Asian Journal of Physics                                                                                                           Vol 25, No 7 (2016) 881-894


Variability of gratings manufactured by interference lithography


Felix Koch1,*, Matthias Burkhardt1, Dennis Lehr1, Mike Schnabel1, Michael Helgert1Renate Fechner2, Frank Frost2, and Tilman Glaser1

1Carl Zeiss Jena GmbH, Microstructured Optics, Jena, Germany

2Leibnitz Institute for Surface Modification, Leipzig, Germany

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Diffraction gratings are utilized in many high-end optical systems, including high-resolution low-straylight spectrometers, monochromators for extreme ultraviolet lithography, and high-power ultrashort laser pulse shaping. The gratings have to meet advanced requirements regarding substrate geometry, grating profiles, diffraction efficiency, and scattered light level. In this paper, we show that interference lithography is a versatile and well-adapted fabrication technology, even for today’s most demanding specifications. Key manufacturing aspects namely substrate geometry, exposure setup, exposure, development, etching, and scattering measurement are discussed. The flexibility of interference lithography is demonstrated by realizing spectroscopic gratings with reduced scattered light, a grazing-incidence extreme-ultraviolet grating with a diffraction efficiency of up to 32%, and highly dispersive pulse compression gratings reaching up to 96% efficiency © Anita Publications. All rights reserved.

Keywords: Diffraction gratings, Ultraviolet lithography, Diffraction efficiency

Total Refs: 40 

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Asian Journal of Physics                                                                                                           Vol 25, No 7 (2016) 897-906

 

Efficiency-achromatized reflective dispersion grating by a double-blaze configuration:

Theoretical conditions for optimal material selection


O Sandfuchs1 and R Brunner2,3

1. University of Applied Sciences Hamm-Lippstadt, 59063, Germany

2. University of Applied Sciences, Applied Optics, Jena, 07745, Germany

3.Fraunhofer Institute for Applied Optics and Precision Engineering, Jena, 07745, Germany

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Blazed gratings are key components both for imaging and for spectrally analyzing optical systems. However, the blazing effect is very sensitive towards wavelength variations. Double-blazed gratings overcome this disadvantage but have been investigated up to now only for transmission geometries. Here we present a systematical theoretical analysis of the diffraction efficiency of double-blazed gratings in the reflection geometry. We find appropriate conditions for a systematical material selection to achieve efficiency-achromatized blazed gratings, based on fundamental dispersion parameters such as the Abbe’s number and relative partial dispersion of the materials. We discuss how to keep the profile heights as shallow as possible. Therefore, appropriate material combinations which are suitable for spectral blazed gratings have to be found. © Anita Publications. All rights reserved.

Key Words: Blazed gratings, Diffraction efficiency, Abbe’s number

Total Refs: 13

Efficiency-achromatized reflective dispersion grating by a double-blaze configuration: Theoretical conditions for optimal material selection.pdf
O Sandfuchs and R Brunner

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Asian Journal of Physics                                                                                                           Vol 25, No 7 (2016) 907-921

Micro-Optics for Biomimetic Vision Systems


Reinhard Voelkel

SUSS MicroOptics SA, Rouges-Terres 61, CH-2068 Hauterive, Switzerland

e-mail: reinhard.voelkel@suss.com

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Mobile phone cameras are a flagship feature of a flagship device. Customers will always opt for the better or more prestigious camera. The scaling law of optics and the related space bandwidth product (SBP) describe the difficulties to further improve camera resolution without increasing the camera size and thickness. The demand for higher and higher image quality of mobile phone cameras requires new strategies for image capturing sensor systems. When a vision system needs to be very small, very fast orhas to operate with minimum resources, then Nature is an excellent teacher. Nature has struggled with the scaling law of optics since more than 500 million years. The paper summarizes different biomimetic strategies for miniaturization of mobile phone vision systems. © Anita Publications. All rights reserved.

Keywords: Mobile phone camera, Biomimetic strategies, Bandwidth

Total Refs: 22

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Asian Journal of Physics                                                                                                                Vol 25, No 7 (2016) 923-955


Silicon Photonics Technology : Ten Years of Research at IIT Madras, Chennai, India

 

B K Das, N Das Gupta, S Chandran, S Kurudi, P Sah, R Nandi, Ramesh K, Sumi R, S Pal, aushal,

S M Sundaram, P Sakthivel, Sidharth R, R Joshi, H Sasikumar, U Karthik,    

S Krubhakar, G R Bhatt, J P George, R K Navalakhe, Narendran R, and I Seethalakshmi

Integrated Optoelectronics Labs, Department of Electrical Engineering, IIT Madras,Chennai - 600 036, India

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The integrated optoelectronics research group at IIT Madras has been active since 2007 with a determination towards developing a center of excellence for silicon photonics research. The core research theme involves novel designs, CMOS compatible fabrication process optimizations and subsequent experimental demonstrations leading towards cost-effective, energy-efficient and high-speed optoelectronic interconnects for various applications. As of now, various prototype devices like power splitters, ITU channel interleavers, variable optical attenuators, p-i-n phase shifters/modulators, ring resonators, DBR filters etc., have been demonstrated by exploiting conventional microelectronics technology as well as recently established nano-fabrication facilities at IIT Madras. Their design principle, process development, fabrication and characterizations are described in the present article. © Anita Publications. All rights reserved.

Keywords: Optoelectronics, p-i-n phase shifters/modulators, Ring resonators, DBR filters.

Total Refs: 42

Silicon Photonics Technology : Ten Years of Research at IIT Madras.pdf
B K Das and et al

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