pi selim m shahriar northwestern university：西北大学塞利姆m该pi

PAC Meeting, Nov. 2006, MIT NU and TAMU Proposal /Shahriar,Scully,ZubairyPI: Selim M. Shahriar / Northwestern University Collaborative Research: A White Light Cavity using Anomalous Dispersion for High-Sensitivity, Broadband Operation of the Next-Generation LIGO SystemCoPIs: Marlan Scully / Texas A the measurement of o allows measurement of L For a generic White Light Cavity (WLC), the frequency shift needed to restore resonance is:WHITE LIGHT CAVITY: Enhanced Sensitivity For ideal WLC (ng=0), no amount of frequency shift restores resonance In practice, the enhanced sensitivity is given by:PAC Meeting, Nov. 2006, MIT NU and TAMU Proposal /Shahriar,Scully,Zubairy Postive Dispersion (Slow Light) Reverses the EffectsOPPOSITE EFFECT UNDER POSITIVE DISPERSION The sensitivity to cavity length change is highly reduced: Linewidth becomes narrower (ng0) :OBVIOUS CANDIDATE FOR WLC: Resonant Two-level System|1|2, = - oAnomalousdispersionProblem: Strong absorption at line centerALTERNATIVE APPROACH: Double-peak Raman GainL.J. Wang, A. Kuzmich, and A. Dogariu, Nature, 406, 277 (2000). FAST LIGHT USING ANOMALOUS DISPERSIONL.J. Wang, A. Kuzmich, and A. Dogariu, Nature, 406, 277 (2000). Inside pulse delayed by:T=L/Vg-L/C=(ng-1)L/CInside pulse advanced by:-T=(1-ng)L/CDual-Frequency PumpProbeF=2F=35S1/25P3/2Optical pumpOUR SCHEME FOR SLOW AND FAST LIGHT IN ONE SYSTEMANOMALOUS DISPERSION : BASIC EXPERIMENT Note : Results showing dispersion measurement under double-gain condition for a pump frequency separation of 8 MHz. As shown in the top figure, the gain is adjusted to get a value of group index close to zero.Heterodyne Dispersion Measurement: Bi-frequency Raman Gain Tuning Anomalous Dispersion to Vanishing Group IndexDISPERSIVE MEDIUM IN A RESONATORCavity Resonance Condition (c= o)Dispersive MediumPumpProbeOpticalpumpCavitylock= medium lengthPhase-sensitivedetectionPos. DispersionNeg. DispersionDISPERSIVE MEDIUM IN A RESONATORPos. Disp.: Linewidth Narrowing and Reduced Sensitivity ExperimentSimulationDetuned Cavity showing Reduced Sensitivity Simulation of Slow-Light Medium in a Resonator Assumes a medium with group index ng 10 Empty cavity linewidth 10 MHz; Disp. linewidth = 1 MHzFrequency Shifts and Group Index DependencePAC Meeting, Nov. 2006, MIT NU and TAMU Proposal /Shahriar,Scully,ZubairyWLC Demonstration using Double-Gain Anomalous DispersionExperiment SimulationEffect of Group Index on WLC Broadeningng = 0.396ng = 0.114Effect of Reduced FSR of the CavityFSR = 300 MHzFSR = 187 MHzEffect of Cavity Path Length Variation: Enhanced SensitivityEffect of Cavity Path Length Variation: Enhanced SensitivityPAC Meeting, Nov. 2006, MIT NU and TAMU Proposal /Shahriar,Scully,ZubairyPART 2: Relevance to LIGO of the proposed work The WLC would enhance the Sensitivity-Bandwidth Productof the Advanced LIGO However, the design for the Advanced LIGO is already too firmlyestablished for such a modification Therefore, we believe that the WLC cavity will be relevant to the Third-Generation LIGO. PAC Meeting, Nov. 2006, MIT NU and TAMU Proposal /Shahriar,Scully,ZubairyNd:YAGLaser PRMSRMDET.BSMBASIC FEATURES OF ADVANCED LIGOPAC Meeting, Nov. 2006, MIT NU and TAMU Proposal /Shahriar,Scully,ZubairyLimitation of Advanced LIGO: Sensitivity-Bandwidth ProductDetectorSignal Sensitivity-Bandwidth Product is fixed by system parameters Sensitivity is of paramount importance for Advanced LIGO design Problem for inherently broadband and chirped sources Several ideas have been proposed to solve this problem. These include 1. (i) Simply broadband dual recycling (ii) Frequency agile interferometers that 2. can follow a chirp, and (iii) input/output cavity techniques that can make 3. optimal filters for specific source spectra. Our approach seems the simplest, 4. and is to be compared/contrasted with these as part of this proposalPAC Meeting, Nov. 2006, MIT NU and TAMU Proposal /Shahriar,Scully,ZubairyEnhancing Sensitivity-Bandwidth Pro