Proposal for Being a KAGRA Member

July 30, 2012

Kyuman ChoDepartment of Physics, Sogang University

OVERVIEW

I. Introduction

− Sogang University

− Photonics Lab

II. Recent Researches on Interferometry

III. Research Plan

I. Introduction

City HallSogang U.

Seoul

Han River

Yonsei Univ.

Ewha Womans Univ.

Sogang Univ.Hongik Univ.

Shinchon ( 新村 ) Area

OverviewHistory

Established in 1960 by American Jesuits

Faculty: 402 Full-time, tenure-track faculty members

StudentsUndergraduate: 8,000

Graduate: 4,000

Over 1,000 international students

Many courses taught in English

Ranked #1 in National Customer Satisfaction Index survey in 1998, 1999, 2003, 2004, 2006

Ranked #1 in Korean Standards-Service Quality Index sur-vey in 2007, 2009, 2010

Academic ProgramSchool of Humanities

School of Social Sciences

School of Natural Sciences

Mathematics

Physics

Chemistry

Life Science

School of Engineering

School of Economics

School of Business Administration

School of Communication

College of Natural Sci-ences

Department of Physics17 Professors

Particle Physics

Condensed Matter Physics

Optics

BK21 Project

World Class University Project

Center for Quantum SpaceTime

Center for Quantum Chaos Applications

http://physics.sogang.ac.kr

Researches in Photonics Lab

Modulation(Phase, Frequency

Amplitude, Intensity)

Demodulation(Phase, Frequency

Amplitude, Intensity)

Physical, Chemical,Biological Phenomena

Linear andNon-Linear

Optics

Sensors

Interferometry High-resolution scanning optical microscope High sensitivity readout sensors for biochips and micro-fluidic channels Measurement of magnetic birefringence in vacuum Precision sensor for measuring displacement, current, magnetic field, etc.

BES for plasma diagnostics NSOM, etc

FSO communications for subscriber service (fixed & moving) Visible light communications

Data, InformationContents, etc.

Data RecoveryOptical

Communications

Measurementsof Optical

Parameters

Transmission LineFiber & FSO

Members and CollaboratorsCurrent Members

Post Doctoral Fellow: Dr. Youngkyu Park Ph.D. Students:

− Seung Hyun Yoon− Seang Hor Eang− Joonkyu Park

Undergraduate Intern: Yongjae Kim

International CollaboratorsProf. Christopher C. Davis, University of Maryland, USAProf. Anatoly Zayatts, Kings College, UKDr. Igor Smolyaninov, BAE System, USA

Domestic Collaborators fromUniversities: Korea Univ., Postech, Yonsei Univ., Ewha Univ., etc. Research Institutions: ETRI, KIST, KETI, etc.Industries: POSCO, GSI, NanoStorage, KAC, etc.

Recent Researches on Interferometry

Research SubjectsOne of the pioneers in the homodyne and heterodyne I/Q-interferometer: The 1st version of the homodyne and heterodyne I/Q-interferometer was developed in 1994 and 1995, respectively.Have been designing and optimizing homodyne and heterodyne I/Q-interferometers for various applications:

Scanning interferometerbiosensors,vibrometer, and the other high sensitivity and wide dynamic range measurements in both academic and industrial applications

Have been working on feasibility study for measuring magnetically induced birefringence in vacuum:

A balanced homodyne scheme was proposed in 1991.Improved version of the MIBD was submitted to NSF and KRF in 2010 and 2012, respectively. Still looking for a proper funding.

Optical I/Q-Demodulator

PBS1

PBS2

BS or PBS

( )Si tSE e

( )LOi tLOE e

HWP

HWPQWP

Can measure amplitude and phase change of the probe beam simultaneously

No need for feedback control to maintain optimum sensitivity

Application Example

Scanning Interferometer for complex surface diagnostics

RF I/Q-Demodulator

Application Example

Scanning Interferometer for complex surface diagnostics

Application Example

Phase and amplitude images of a patterned surface

Application Example

Wide measurement range interferometer

An astigmatic position sensing scheme is integrated to the heterodyne I/Q-interferometer.

The interference signal is used for high resolution measurement while the astigmatic sensor is used for wide range measurement.

Application Example

Scanning results (step height 3 μm)

Application Example

New arrangement using double pass in AOM

The equivalent minimum displacement ~ 5 x 10-13 m

Application Example

Vibration Measurement

The topography (a), amplitude (b), and color-scaled amplitude (c)

Application Example

Scanning microscopy

In

Out

Application Example

Readout sensor for a fluidic channel

Sample

I Q

Dual mode laser

OL

K. H. Kwon, B. S. Kim, and K. Cho, OPTICS EXPRESS, 16, 13456 (2008)

Dual mode laser

OL

Constant-Phase Scanning Heterodyne Interferometer

BS : Beam splitterPBS : Polarization Beam SplitterPOL : PolarizerM : MirrorHWP : Half Wave PlateQWP : Quarter Wave PlatePD : Photo DiodePZT : Piezoelectric TransducerOI : Optical isolatorOL : Objective Lense

Application Example

The proposed microscope can measure both amplitude and phase simultaneously.

The reflectivity image of the constant-phase scanning microscope is more clear

than that of the HIQI.

(a), (c) : constant-phase scheme, (b), (d): conventional scheme

Application Example

Scanning Results

Proposed Scheme for Measuring MILB

Laser

QWP

PBS

M1

M2

Magnet

OI Pol

PD1

PD2

DA

B

Two Faraday rotators are used to rotate the modulation principal axes.

This scheme can provide the same modulation effects as rotating the magnet.

The modulation frequency can go up to tens of Hz which is high enough to minimize 1/f-noise.

No possible artifacts can be expected at the measurement frequency.

Current Source

CP

FR(F) FR(-F)

AA

Application Example

Proposed scheme for measuring MIB

Research Plan

Advanced Lab for GWD

Will do our best to get a proper research grantA big grant proposal has been submitted.Keep looking for grant opportunities if it is not awarded.

Will concentrate on the researches on GWD.Perform extensive researches on GWDCreate new ideas for improving the sensitivity of the GWD

Establish a lab for building a prototype interferometer.Gaining experiences on the large scale interferometer.Testing new ideas for the GWD

Establish active research network with KAGRA membersArrange regular meetings. (Ex: Prof. Shiniji Miyoki’s visit)Exchange knowledge, ideas, and members.

Suggested KAGRA Collaboration Members

Prof. Christopher C. Davis, Dept. of ECE, Univ. of MD. Mentor of the Photonics Lab.Tens of years of experiences on interferometry, sensors, and optical communicationsCollaborator for designing interferometric measurement scheme for MIB.

Dr. Youngkyu Park, Dept. of Phys., Sogang University

Ph.D. Students in Dept. of Phys., Sogang Univ.Seung Hyun YoonSeang Hor EangJoonkyu Park