Abstract We experimentally investigate the scanning nonreciprocity of four-wave mixing process induced by optical parametric amplification in moving photonic band gap, which is different from the propagation nonreciprocity in the optical diode. Meanwhile the frequency offset and the intensity difference are observed when we scan the frequency of the beams on two arm ramps of one round trip. Such scanning nonreciprocities can be controlled by changing the frequency detuning of the dressing beams. For the first time, we find that the intensity difference can cause the nonreciprocity in spatial image. In the nonreciprocity process, the focusing or defocusing is resulted from the feedback dressing self-phase modulation while shift and split is attributed to feedback dressing cross-phase modulation. Our study could have a potential application in the controllable optical diode.
Abstract We experimentally investigate the scanning nonreciprocity of four-wave mixing process induced by optical parametric amplification in moving photonic band gap, which is different from the propagation nonreciprocity in the optical diode. Meanwhile the frequency offset and the intensity difference are observed when we scan the frequency of the beams on two arm ramps of one round trip. Such scanning nonreciprocities can be controlled by changing the frequency detuning of the dressing beams. For the first time, we find that the intensity difference can cause the nonreciprocity in spatial image. In the nonreciprocity process, the focusing or defocusing is resulted from the feedback dressing self-phase modulation while shift and split is attributed to feedback dressing cross-phase modulation. Our study could have a potential application in the controllable optical diode.
We investigate the optical nonreciprocity induced by the parametrical amplification and the radiation trapping in an atomic photonic bandgap system both theoretically and experimentally. We use two pumping fields to generate entangled photon pairs from spontaneous parametric four-wave mixing, as well as the signals in which they can be enhanced by the feedback dressing effect. Therefore, the frequency difference and the shape change due to this feedback dressing on the two-arm ramps of one round trip are observed. Such optical nonreciprocity can be easily controlled by multiple experimental parameters (frequency detuning, power, and phase) of the dressing beams. In addition, the enhancement and suppression switching induced by the double dressing or triple dressing conditions are also studied. This optical nonreciprocity can contribute to the development of quantum information processing and quantum communications.
We investigate the nonreciprocity "∞"-shape optical bistability (OB) induced by the feedback dressing effect of six-wave mixing parametrically amplified process in a four-level atomic system. Compared to the traditional OB by scanning power, the "∞"-shape OB is scanning probe frequency and demonstrated by "∞"-shape non-overlapping region. More, this non-overlapping region in the x direction (frequency difference) and in the y direction (intensity difference) could demonstrate the degree of this OB phenomenon of dressed probe and conjugate signals, which can be changed by the intensity of feedback dressing. Further, we find the feedback intensity can be controlled by experimental parameters include powers of external-dressing, frequency detuning, incident phase and the nonlinear phase shift of internal-dressing beam. As a result, the nonreciprocity "∞"-shape OB is more sensitive and multiple than traditional OB. These outcomes have potential applications in logic-gate devices and quantum information processing.
For the first time, to the best of our knowledge, we investigate the photonic band gap (PBG) structure through scanning the frequency detunings of the probe field, the dressing field, and the coupling field in the static and moving electromagnetically induced grating (EIG) field. When we scan the frequency detuning of the coupling field, the PBG structure and six-wave-mixing band gap signal (SWM BGS) appear at the right of the electromagnetically induced transparency (EIT) position. But the PBG structure and SWM BGS appear at the left of the EIT position in the case of scanning the probe field frequency detuning. Also, on the condition of scanning the probe field frequency detuning, the SWM BGS appears in two frequency ranges. Moreover, in the moving PBG structure, nonreciprocity of the SWM BGS can be obtained. Furthermore, the intensity, width, and location of the SWM BGS can be modulated through changing the frequency detunings and intensities of the probe field, the dressing field, and the coupling field; the sample length; and the frequency difference of coupling fields in EIG. Such a scheme could have potential applications in optical diodes, amplifiers, and quantum information processing.
Three and four electromagnetically induced transparency windows generate the multi-channel four-wave mixing (FWM) process are observed in a four-level atomic system. The transmission of the probe field and the reflection of the FWM are investigated in the modulated moving photonic band gap structures which are caused by the coupling fields with a relative small detuning offset when scanning detuning frequency of the probe field and the dressing field, respectively. The experimental results show that the more channels spectrum signal of the FWM process can be modulated and the generated multi-channel can be further modulated by adding a dressing field. We have also explained theoretically these experimental results which may have applications in the design of photonic crystal and optical signal amplifiers.
For the first time, we investigate the nonreciprocal generation of six-wave mixing (SWM) in an inverted-Y type four-level system with spatially uniform distribution of atoms. The nonreciprocity results from a moving electromagnetically induced grating (EIG) which is formed by two coupling beams with different frequencies. We demonstrate that the nonreciprocity can be controlled by the frequencies of the coupling fields and the powers of the dressing beams. As the distribution of atoms is uniform, the atomic density cannot affect the nonreciprocity, but it will affect the formation of the photonic band gap structure of the moving EIG. This research can be used to make optical diodes or optical isolators, because the moving EIG, the speed of which is related to the frequency difference of the two coupling beams, can break time-reversal symmetry. We also demonstrate that the nonreciprocal SWM can form a nonreciprocal light droplet when it propagates in atomic vapors with third- and fifth-order nonlinear susceptibilities.
Abstract For the first time, we have experimentally and theoretically researched the double dressing effect on the six wave mixing photonic band gap signal (SWM BGS), probe transmission signal (PTS) and fluorescence signal (FLS) in an inverted Y-type four level atomic system. We investigate the characteristics of the SMW BGS, PTS and FLS, which can be controlled by beam, power and detuning. At the same time, the relative phase which is caused by the incident angle of dressing beams plays a vital role in modulating the intensity of the SWM BGS, PTS and FLS. Such a scheme has potential applications in optical diodes, amplifiers and quantum information processing.