Broadband Linewidth Research Articles

V type three-level symmetric second-order coherence theory of attosecond polarization beats

Based on the phaseconjugate polarization interference between two onephoton processes, we have studied theoretically the symmetric sumfrequency polarization beat (SFPB) of V type threelevel system in attosecond scale in the case of arbitrary bandwidth or broadband linewidth laser. The homodyne detected SFPB signal is shown to be particularly sensitive to the statistical properties of the Markovian stochastic light fields with arbitrary bandwidth. We have found that the accuracy in the measurement of the energylevel sum of two excited states which are dipolar forbidden transition to each other is determined by the homogeneous linewidths of the optical transitions and exceeds the laser linewidth. A Dopplerfree precision in the measurement of the energylevel sum can be achieved with an arbitrary bandwidth. The field correlation has weakly influence on the SFPB signal when the laser has a narrow bandwidth. When the laser has a broadband linewidth, the SFPB signal shows resonantnonresonant cross correlation. As an attosecond ultrafast modulation process, SFPB can be extended intrinsically to any sumfrequency of energylevels.

Correlation effects of chaotic and phase-diffusion fields on polarization beats in a V-type three-level system

Abstract The correlation effects of fourth-order on polarization beats in a V-type three-level system (PBVTS) are investigated using chaotic and phase-diffusion models. It has been found that the temporal behaviour of the beat signal depends on the stochastic properties of the lasers and transverse relaxation rate of the transitions, and the modulation terms of the beat signal depend on the second-order coherence function, which is determined by the laser line shape. Since different stochastic models of the laser field affect only the fourth-order coherence function, they have little influence on the general temporal modulation behaviour of the beat signal. The different roles of the phase fluctuation and amplitude fluctuation have been pointed out in the time domain. The fourth-order coherence function theory of chaotic field is of vital importance in PBVTS. The cases where the pump beams have either narrow band or broadband linewidth are considered and it has been found that for both cases a Doppler-free precision in the measurement of the energy-level splitting between two states can be achieved. Finally, the difference between the PBVTS and DeBeer's ultrafast modulation spectroscopy is discussed as well from a physical viewpoint.

Higher-order correlation on polarization beats in Markovian stochastic fields

The correlation effects of sixth order on cascade three-level polarization beats are investigated using chaotic field, phase-diffusion, and Gaussian-amplitude models. The polarization beat signal is shown to be particularly sensitive to the statistical properties of the Markovian stochastic light fields with arbitrary bandwidth. Different stochastic models of the laser field only affect the sixth- and fourth-order coherence functions. The constant background of the beat signal originates from the amplitude fluctuation of the Markovian stochastic fields. The Gaussian-amplitude field shows fluctuations larger than the chaotic field, which again exhibits fluctuations much larger than for the phase-diffusion field with pure phase fluctuations caused by spontaneous emission. The cases that the pump beams have either narrowband or broadband linewidth are considered and it has been found that for both cases a Doppler-free precision in the measurement of the energy-level difference of the excited states can be achieved. The sixth-order coherence function theory is of vital importance in cascade three-level polarization beats.

Correlation effects of chaotic and phase-diffusion fields on polarization beats in a V-type three-level system

The correlation effects of fourth-order on polarization beats in a V-type three-level system (PBVTS) are investigated using chaotic and phase-diffusion models. It has been found that the temporal behaviour of the beat signal depends on the stochastic properties of the lasers and transverse relaxation rate of the transitions, and the modulation terms of the beat signal depend on the second-order coherence function, which is determined by the laser line shape. Since different stochastic models of the laser field affect only the fourth-order coherence function, they have little influence on the general temporal modulation behaviour of the beat signal. The different roles of the phase fluctuation and amplitude fluctuation have been pointed out in the time domain. The fourth-order coherence function theory of chaotic field is of vital importance in PBVTS. The cases where the pump beams have either narrow band or broadband linewidth are considered and it has been found that for both cases a Doppler-free precision in the measurement of the energy-level splitting between two states can be achieved. Finally, the difference between the PBVTS and DeBeer's ultrafast modulation spectroscopy is discussed as well from a physical viewpoint.

Interference effects in different fifth-order polarizations with broadband noisy light

Based on the second-order coherence function, we have studied a phase-conjugate ultrafast modulation spectroscopy due to the interference between the fifth- and fifth-order optical polarizations in cascade three-level Doppler-broadened system. It is found that the temporal behaviour of the beat signal depends on the stochastic properties of the lasers and the transverse relaxation rate of the transition. The beat signal depends on the second-order coherence function, which is determined by the laser line shape. Since different stochastic models of the laser field only affect higher than second-order coherence functions, they have little influence on the general temporal modulation behaviour of the beat signal. The cases that pump beams have either narrow band or broadband linewidth are considered and it has been found that for both cases the overall accuracy for the energy-level difference measurement is determined by the homogeneous linewidths of the optical transitions. Finally the spatial modulation behaviour of the beat signal has also been discussed.

Sixth-order correlation on Raman-enhanced polarization beats with phase-conjugation geometry

The correlation effects of sixth-order on the Raman-enhanced polarization beats (REPB) with phase-conjugation geometry in carbon disulfide are investigated using chaotic and phase-diffusion models. Based on two types of models, the cases that the pump beams have either narrow band or broadband linewidth are considered and it is found that the beat signal oscillates not only temporally with a 50.5 fs period but also spatially. The overall accuracy of using REPB to measure the resonant frequency of Raman-active vibrational mode is determined by the relaxation rates of the Raman mode and the molecular-reorientational grating. Moreover, the temporal behavior of the beat signal depends on the stochastic properties of the lasers and the decay rates of the Raman mode and the molecular-reorientational grating. Different stochastic models of the laser field only affect the sixth- and fourth-order coherence function. Furthermore, the different roles of the phase fluctuation and amplitude fluctuation have been pointed out in the time domain. The difference between the REPB and the fourth-order coherence on ultrafast modulation spectroscopy is discussed as well from a physical viewpoint. Therefore, the sixth-order coherence function theory of chaotic field is of vital importance in REPB.

Nonlinear effects of third-and fifth-order on polarization beats in a four-level system

We have employed second-order coherence function theory to study the nonlinear effects of third-and fifth-order on polarization beats in a four-level system (TPBFS and FPBFS). It is found that the different temporal behavior of the beat signal in TPBFS and FPBFS depends on the stochastic properties of the lasers and transverse relaxation rate of the transition. We have considered the cases that pump beams have either narrow band or broadband linewidth and found that for both cases a Doppler-free precision can be achieved in the measurement of the energy-level difference between two excited states which are dipolar forbidden from the ground state. We also discussed the spatiall modulation behavior of the beat signal.

Fourth-order interference on polarization beats in a four-level system

We have employed chaotic and phase-diffusion models to study the effects of laser fourth-order coherence on polarization beats with phase-conjugation geometry in a four-level system (PBFS). We found that the temporal behavior of the beat signal depends on the stochastic properties of the lasers and the transverse relaxation rate of the transition. The modulation terms of the beat signal depend on the second-order coherence function, which is determined by the laser line shape. Inasmuch as different stochastic models of the laser field affect only the fourth-order coherence function, they have little influence on the general temporal modulation behavior of the beat signal. The different roles of phase fluctuation and amplitude fluctuation are pointed out. The cases that pump beams have either narrow-band or broadband linewidth are considered, and it is found that for both cases a Doppler-free precision in the measurement of the energy-level difference between two states that are dipolar forbidden from the ground state can be achieved. We also discuss the difference between the PBFS and ultrafast modulation spectroscopy from a physical viewpoint.

Effects of field correlation on polarization beats

We have employed a second-order coherence function theory to study the effect of laser coherence on polarization beats in four-level system (PBFS). It is found that the temporal behavior of the beat signal depends on the stochastic properties of the lasers and transverse relaxation rate of the transition. The cases that pump beams have either narrow band or broadband linewidth are considered and it has been found that for both cases a Doppler-free precision in the measurement of the energy-level splitting between two excited states which are dipolar forbidden from the ground state can be achieved. We have also studied the asymmetric behavior of the polarization beats, and attributed this asymmetry to the shift of the zero time delay which is due to the dispersion of the optical components.

Effects of fourth-order coherence on ultrafast modulation spectroscopy

The effect of fourth-order coherence on ultrafast modulation spectroscopy with phase-conjugation geometry (PCUMS) in a cascade three-level system is investigated using chaotic and phase-diffusion models. It has been found that the temporal behavior of the beat signal depends on the stochastic properties of the lasers and the transverse relaxation rate of the transitions, and the modulation terms of the beat signal depend on the second-order coherence function, which is determined by the laser line shape. Since different stochastic models of the laser field affect only the fourth-order coherence function, they have little influence on the general temporal modulation behavior of the beat signal. The different roles of the phase fluctuation and amplitude fluctuation can be investigated in the time domain. The cases where the pump beams have either a narrow or broad band linewidth are considered and it has been found that for both cases a Doppler-free precision in the measurement of the energy-level difference between two states can be achieved. The difference between the PCUMS and the DeBeer, UMS [D. DeBeer et al., Phys. Rev. Lett. 56, 1128 (1986)] is discussed as well from a physical viewpoint.

ASYMMETRIC BEHAVIOR OF THE POLARIZATION BEATS SIGNAL IN A FOUR-LEVEL SYSTEM

We have studied the asymmetric behavior of the polarization beats in a four-level system when the pump beams have either narrowband or broadband linewidth, we attribute this asymmetry to the shift of the zero time delay which is due to the dispersion of the optical components.

THEORETICAL STUDY OF THE FIFTH-ORDER POLARIZA-TION BEATS IN A FOUR-LEVEL SYSTEM

We have studied theoretically a beat effect in a four-level system due to fifth-order optical polarization, and considered the cases that the pump beams have either narrowband or broadband linewidth. We have found that the accuracy for the energy-level splitting meaurement is determined by the homogeneous linewidths of the optical transitions. That is to say, this technique can achieve Doppler-free precision in the measurement of the eaergy level splitting between two excited states which are dipolar forbidden from the ground state.

Effects of Field-Correlation on Raman-Enhanced Nondegenerate Four-Wave Mixing Spectra

The effects of field correlation on Raman-enhanced nondegenerate four-wave mixing (RENFWM) have been investigated by examining the RENFWM spectra as a function of time delay between two beams. An enhancement of the ratio between the resonant and nonresonant RENFWM signal intensities was found as the time delay was increased when the laser had broadband linewidth.

Doppler-free ultrafast modulation spectroscopy with phase-conjugation geometry.

We have studied theoretically a phase-conjugate ultrafast modulation spectroscopy (PCUMS) in a Doppler-broadened system. The pump beams consist of two frequency components which drive two different transitions. It is found that the four-wave-mixing (FWM) signal exhibits damping oscillation as the relative time delay between two pump beams is varied, from which the energy-level splitting can be deduced. We have considered the cases that pump beams have either narrow band or broadband linewidth and found that for both cases a Doppler-free precision in the measurement of the energy-level splitting can be achieved. The advantage of PCUMS is that the energy-level splitting between states can be widely separated. Finally, the relationship between PCUMS and other Doppler-free techniques in frequency and time domains has also been discussed.

Broadband Linewidth Measurement of Low Q Hexagonal, Ferrimagnetic Resonators

Broadband linewidth measurement of high anisotropy planar ferrites (MnZnY) has been accomplished using an extension of the nonresonant matched method reported by Matthaei. This former method required 3-dB bandwidth measurements resulting from an approximate expression for Q. The present technique combines an exact expression for the unloaded Q of a bandstop filter with a linewidth representation for a high anisotropy planar ferrite. The resulting expression permits the calculation of linewidth over a broad range of frequencies for a low Q resonator, characteristic of hexagonal ferrites at high microwave frequencies. Calculation of linewidth can be obtained from essentially an arbitrary bandwidth and where the maximum rejection of a ferrimagnetic bandstop filter is less than 3 dB.