Dr. BIPLAB BHAWAL,
LIGO Laboratory, Division of Physics, Mathematics and Astronomy,
California Institute of Technology , Pasadena , CA 91125, USA.
Office location: 364 West Bridge, Fax: 626-584-5735, TEL: 626-395-4437
Broad Research Interest: Detection of Gravitational Waves
Popular articles on Gravitational Waves in various magazines and journalsOr Read this book online: "Einstein's Unfinished Symphony" by Marcia Bartusiak
To learn how interferometric gravitational wave detectors work, read this paper :
"Physics of Interferometric Gravitational Wave Detectors"
based on Biplab's plenary talk in International Conference on Gravitation & Cosmology (ICGC'04).
A) Recent Research Activities:
(xiii) 'Diffraction Losses and Parametric Instability in Advanced LIGO':
-- (Collaboration with David Blair's group at Univ. of Western Australia, Canberra). Biplab's results on diffraction losses and ideal 'clipping' losses of higher order spatial modes are here .
-- Technical Note summarizing Diffraction loss results.
-- Example of how Gaussian Modes can get distorted by too much diffraction loss: Figures for TEM70 are here
-- Viewgraphs of Biplab's talk in the meeting on {\it Parametric Amplification}, Caltech, Aug 23, 2005
-- Viewgraphs of David Blair's talk in LSC meeting.
(xii) Summer Research by Undergraduate Students:
-- Viewgraphs of SURF presentation by Doug Fettig, Oregon State U.
-- Viewgraphs of Talk in LSC meeting by Nafis Jamal (Stanford U.) and Shivanand (IIT Kharagpur, India).
-- Final report by Doug Fettig, Oregon State U.
(xi) Modal decomposition of PhaseCam measurements:
-- Viewgraphs of Talk in Workshop on "Spatial Properties of IFOs", January 31-February 01, 2005.
-- Viewgraphs of Talk in E2E Physics Meeting, Nov 18, 2004.
-- H1 Antisymmetric Port results available here
(x) Matlab package "FFTprop" (released Oct'2004):
-- Can (i) propagate beam intensity profile through lenses and distances (ii) do back-calculation to know how the intensity profile looks like at a point already passed through by the beam. Available here
(ix) Effect of Thermal lensing on Wavefront Sensors :
-- Effect of Thermal Lensing on Wave-Front Sensor Signals Talk in LIGO Science Collaboration meeting (Mar 23, 2004) at LLO, Livingston, LA.
-- The Effect of Thermal Lensing on Wave-Front Sensor Signals (LIGO Technical document T040066-00-E).
-- Effect on WFS2: Viewgraphs of presentation in Thermal Compensation meeting, Feb 20, 2004.
(viii) Caltech's E2E & MIT's FFT :
-- How to compare results: LIGO Technical document no. T030284-00-E.
(vii) Wavefront Sensor Set-up/Loops :
--Variation in Gouy phase and Width of beams in all WFS set-ups at LLO: (LLO elog, 2nd July'04).
-- Stability of the WFS loops which are currently in implementation at LHO (Sept'03).
(vi) FFT Studies: Effect of mirror phasemaps on Gravitational Wave sensitivity :
-- Presentation in E2E Physics meeting Sept 2, 2004: Mirror Phasemaps and WFS signals
-- Presentation in LIGO commissioning meeting July 12, 2004: Viewgraphs
-- The phasemaps for POY field have been posted on May 17, 2004: Carrier and Sideband maps
--Files can be accessed from Caltech LIGO network in /home/bbhawal/sun4/FFT/ . Read the README file for instructions.
(v) Wavefront Sensor Signals :
-- LIGO Technical Document: The Wavefront Signals from E2E's 6-optics LIGO System
-- Reflected port signals demodulated by non-resonant sidebands are different from earlier prediction
-- New WFS signal matrix for as-built LIGO 4 km interferometer
-- WFS signal matrix for recycled Michelson configuration
-- WFS signal matrix for Hanford 2KM interferometer
(iv) LIGO Lock acquisition and angular fluctuations:
-- Histograms and plots showing effects of tilts in various mirrors on lock acquisition
-- LIGO Technical document: Preliminary E2E-Simulation Studies of Lock Acquisition with Misalignments
-- Study of angular fluctuations of Hanford 2-Km IFO during Engineering run E2
(iii) LIGO Lock acquisition :
-- Lock Acquisition of a Gravitational Wave Interferometer
(ii) Frequency sensor noise:
-- Presentation in LSC meeting (Mar'2001) by Brad Zamft, SURF student
(i) Microscopic longitudinal motion in LIGO :
-- LIGO transfer functions: comparison between E2E & Twiddle results
(0) LIGO End-to-End (E2E) simulation model (E2E)
-- Article : proc. of Moriond Conference on Gravitational Waves and Experimental Gravity (Les Arcs, France, Mar'03)
-- Technical Documents: Primitive Document , Modal Model Document
B) Selected Presentations :
"Effect of Thermal Lensing on WFS (FFT study)" (LIGO Science Collaboration Meeting, Livingston, LA, March 20-23, 2005)
"Physics of Interferometric Gravitational Wave Detectors" (Plenary talk in International Conference on Gravitation and Cosmology at Kochi, Kerala, India, January 5-10, 2004)
"The LIGO End-to-End Simulation Program" (Moriond Workshop on Gravitational Waves and Experimental Gravitation, Les Arcs, France, March 25, 2003)
"LIGO as it goes from cold to hot state: E2E simulation study" (LSC conference, LIGO Livingston Observatory, March 22nd, 2002)
"E2E's Physics tools" (E2E school, LIGO Livingston Observatory, March 18th, 2002)
"Locking LIGO with its as-built spatial mode mismatches" (E2E weekly Physics meeting, Caltech, January 23rd, 2002)
"Mode mismatch in LIGO" (LIGO Science seminar, Caltech, November 2nd, 2001)
"LIGO End-to-End simulation model" (Pacific Coast Gravity Meeting, UC, Santa Barbara, March 10, 2001)
Links to Books :
