Phase-conjugate mirror and time reversal

Chew, W. C.; Habashy, Tarek M.

doi:10.1364/josaa.2.000808

Cited by 11 publications

(6 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Note here that the definition of 𝑆 4 involves the conjugated complex signals, consistent with the fact that such a Mathieu slab operates as a phase conjugating mirror [61]. Applying proper boundary conditions to the general solution of Eqs.…”

Section: Ii) Mathieu Slab As a 𝓟𝓣 Symmetric Scattering Systemmentioning

confidence: 86%

Parametric amplification and bidirectional invisibility in PT -symmetric time-Floquet systems

2018

View full text Add to dashboard Cite

Parity-time (PT )-symmetric wave devices, which exploit balanced interactions between material gain and loss, exhibit extraordinary properties, including lasing and flux-conserving scattering processes. In a seemingly different research field, periodically driven systems, also known as time-Floquet systems, have been widely studied as a relevant platform for reconfigurable active wave control and manipulation. In this article, we explore the connection between PT -symmetry and parametric time-Floquet systems. Instead of relying on material gain, we use parametric amplification by considering a time-periodic modulation of the refractive index at a frequency equal to twice the incident signal frequency. We show that the scattering from a simple parametric slab, whose dynamics follows the Mathieu equation, can be described by a PT -symmetric scattering matrix, whose PT -breaking threshold corresponds to the Mathieu instability threshold. By combining different parametric slabs modulated out of phase, we create PT -symmetric time-Floquet systems that feature exceptional scattering properties, such as coherent perfect absorption (CPA)-laser operation and bidirectional invisibility. These bidirectional properties, rare for regular PT -symmetric systems, are related to a compensation of parametric amplification due to multiple scattering between two parametric systems modulated with a phase difference.

show abstract

Section: Ii) Mathieu Slab As a 𝓟𝓣 Symmetric Scattering Systemmentioning

confidence: 86%

Parametric amplification and bidirectional invisibility in PT -symmetric time-Floquet systems

2018

View full text Add to dashboard Cite

show abstract

“…The magnification ratio of this structure is (23) where f andf2 are the focal lengths of the two lenses respectively. So, d<<ta 11 (3) Polarization-Persevered Phase Conjugate Mirror '4 Usually, photorefractive effect is dependent on the polarization orientation of the incident light, so, the phase conjugate mirror reflects only one transverse component of the incident light. So, d<<ta 11 (3) Polarization-Persevered Phase Conjugate Mirror '4 Usually, photorefractive effect is dependent on the polarization orientation of the incident light, so, the phase conjugate mirror reflects only one transverse component of the incident light.…”

Section: Discussionmentioning

confidence: 99%

<title>Fiber specklegram sensing with phase-conjugation</title>

Lü

Yin

1995

SPIE Proceedings

View full text Add to dashboard Cite

A multimode fiber specklegram sensor using phase-conjugate mirror is presented. This sensing technique is based on the phase compensation of phase-conjugate signal, which is very sensitive to external perturbation. The preliminary experiments on displacement measurement are also provided. . INTRODUCTIONOptical fiber sensing is a most promising technology for many industrial observation problems. The basic advantages implicit in optical fiber sensing, such as immunity from electromagnetic interference, chemical resistance, and potentially high sensitivity, make this approach attractive'. A new class of optical fiber sensor, recently proposed by Wu et a12, is based on the specklegram from multimode fiber. Since the speckle distribution is attributed to interference among those guided modes in multimode fiber, the specklegram fiber sensor is of sensitivity as high as interferomethc sensors. Based on the correlation between speckle patterns, this kind of optical fiber sensor has been used to measure displacement, vibration and temperature35. Furthermore, the specklegram fiber sensor can also be used in multichannel sensing because of the high space-bandwidth product of multimode fibers.The high space-bandwidth product of multimode fiber has also been utilized to transmit spatial information.7'8. The key point in this technique is how to reconstruct the spatial information from distortion caused by modal coupling and dispersion. Yariv7 has proposed to retrieve the image using the wave-front-reversal property of phase-conjugate mirror. Such an image transmission technique requires the same phase distribution in forward and backward paths. Therefore, in Yariv's method two identical fiber must be found before this technique can be realized. To overcome that difficulty, Dunning and Lind8 proposed a single fiber architecture, and implemented reconstruction of image transmitting through fiber. Although it is apparently not a practical method because transmitted image can only be reconstructed in the input end of fiber, they successfully demonstrated the process of phase compensation using phase-conjugate mirror. We note that, in Dunning and Lind's architecture the degradation of the image will not be compensated completely when external perturbation exists, and that deviation from original pattern can be utilized to measure that external perturbation. In this Technical Note, a fiber specklegram sensor with phase-conjugate mirror is presented. We analyzed the effect of external perturbation on the reconstructed light field, and the preliminary experimental results of submicrometer displacement sensing are also provided. . PHOTOREFRACTIVE EFFECT AND PHASE CONJUGATIONPhotorefractive effect is a phenomenon in which the local index of refraction of a medium is changed by the illumination of a beam of light with spatial variation of the intensity9. This effect is attributed to the formation of the photoinduced space-charge field and formation of index grating via the linear electro-optic effect ( the Pockles effect). In comparing...

show abstract

“…A phase conjugating mirror (PCM) is a device implementing this approach. An ideal PCM [2] can produce the time-reversal (TR) effect. Essentially, PC can be treated as a specific case of TR, applicable where it is possible to directly manipulate the phase of the received signals.…”

Section: Introductionmentioning

confidence: 99%

“…PCMs described in the literature [2,7,11] may be understood as devices reflecting the incident beam in a phase-reversed sense back along its path [12]. There is a major difference between an ordinary mirror and a phase conjugating mirror [13].…”

Section: Introductionmentioning

confidence: 99%