In this Letter, a scheme for realizing an electromagnetic induced transparency (EIT) analog in the photonic time crystal (PTC) is proposed. Strategies for achieving EIT-like phenomena in PTCs are explored, the transmission matrix method is elaborated, and a time-domain multilayer configuration for EIT-like effects is presented. The EIT-like phenomenon in PTC is analyzed using coupled-mode theory, with phase shifts and group delays discussed to validate the accuracy of the EIT-like phenomenon. Research shows that increasing the modulation depth of the PTC by modulating the refractive index in a temporal slab can effectively enhance the intensity of the EIT-like effect. This provides a feasible technical pathway for realizing EIT-like effects in time-varying systems and lays the foundation for related applications such as slow light technology in the time domain.
In this Letter, a scheme for realizing an electromagnetic induced transparency (EIT) analog in the photonic time crystal (PTC) is proposed. Strategies for achieving EIT-like phenomena in PTCs are explored, the transmission matrix method is elaborated, and a time-domain multilayer configuration for EIT-like effects is presented. The EIT-like phenomenon in PTC is analyzed using coupled-mode theory, with phase shifts and group delays discussed to validate the accuracy of the EIT-like phenomenon. Research shows that increasing the modulation depth of the PTC by modulating the refractive index in a temporal slab can effectively enhance the intensity of the EIT-like effect. This provides a feasible technical pathway for realizing EIT-like effects in time-varying systems and lays the foundation for related applications such as slow light technology in the time domain.
A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency (EIT). The combination of EIT with periodically modulated refractive index medium gives rise to high efficiency reflection as well as forbidden transmission in a three-level atomic system coupled by standing wave. We show an accurate theoretical simulation via transfer-matrix theory, automatically accounting for multilayer reflections, thus fully demonstrate the existence of photonic crystal structure in atomic vapor.
Slow light technique has significant potential applications in many contemporary photonic device developments for integrated all-optical circuit, such as buffers, regenerators, switches and interferometers. In this paper, we present an efficient coupling mechanism of an electromagnetically induced transparency like (EIT-like) effect in an all-dielectric nano-metamaterial. This EIT-like effect is generated by destructive interference between a radiative Fabry-Perot (FP) mode and a dark waveguide (WG) mode, which is based on a combined structure of a dielectric grating and multilayer films. The dark WG mode is excited by guided mode of dielectric grating instead of radiative FP mode. In analogy to the molecular transition process, the FP mode, guided mode and WG mode are denoted by excited states of |1〉, |2〉 and |3〉. The two coupling pathways of the EIT-like effect in our metamaterial are |0〉 → |1〉 and |0〉 → |2〉 → |3〉 → |1〉, where |0〉 is the ground state. The simulated resonant wavelength of WG mode is consistent with theoretical result. We further confirm this EIT-like effect through a two-oscillator coupling analysis. We achieve a group refractive index of 913.6 by adjusting these two modes coupling of the EIT-like effect, which is useful for developing slow light device. This work provides a valuable solution to realize electromagnetically induced transparency in all-dielectric nanomaterial.
An electrodynamic model is presented in this Letter to describe thresholdless lasers, utilizing the application of photonic time crystals (PTCs). By integrating the distinctive physical properties of PTCs and employing a comprehensive model based on a four-level system, the feasibility of achieving thresholdless laser operation is demonstrated. The proposed electrodynamic model comprehensively captures the intricate interplay between the electromagnetic field and the PTC medium. The model takes into account the ultrafast periodic variations in the refractive index of the PTCs, which arise from their time crystal-like behavior. Additionally, the dynamic response of the four-level system is considered, factoring in the processes of population inversion and relaxation. This Letter seeks to elucidate the underlying mechanisms that facilitate thresholdless laser operation in PTC-based systems. Through our electrodynamic modeling approach, we demonstrate that the ultrafast variations in the refractive index of PTCs give rise to a self-sustaining laser action, obviating the need for a lasing threshold. Moreover, we investigate the impact of various parameters, including pump power and modulation period, on the laser's performance and output characteristics. The developed electrodynamic model provides a comprehensive framework for comprehending and designing thresholdless lasers based on photonic time crystals. This research contributes to the advancement of thresholdless laser technology and opens up possibilities for applications in optical communications, sensing, and quantum photonics.
Abstract We present an electrodynamic model for thresholdless lasers based on the utilization of photonic time crystals (PTCs). By incorporating the unique physical properties of PTCs and employing a comprehensive four-level system model, we demonstrate the feasibility of achieving thresholdless laser operation. The proposed electrodynamic model captures the intricate interplay between the electromagnetic field and the PTC medium. We account for the ultrafast periodic variations in the refractive index of the PTCs, which are a result of their time crystal-like behavior. The model considers the dynamic response of the four-level system, taking into account the population inversion and relaxation processes. Through our electrodynamic modeling, we elucidate the underlying mechanisms that enable thresholdless laser operation in PTC-based systems. We demonstrate that the ultrafast refractive index variations lead to a self-sustaining laser action, eliminating the need for a lasing threshold. Moreover, we investigate the influence of various parameters, such as pump power and modulation period, on the laser performance and output characteristics. The electrodynamic model developed in this study provides a comprehensive framework for understanding and designing thresholdless lasers based on photonic time crystals. Our work contributes to the advancement of thresholdless laser technology and paves the way for potential applications in areas such as optical communications, sensing, and quantum photonics.
In this paper, a new counter-propagation waves coupling mechanism is proposed which is expected to realize an electromagnetically induced transparency (EIT)-like effect. Comparing the travelling waves coupling mechanism (see J. Mod. Opt. 2015,62:313-320 [9]) with the counter-propagating waves coupling mechanism, we find out that the transparency window breadths of transmission spectra are greatly enhanced and the corresponding phase shift spectra possess a flat profile or a square profile. Our numerical simulated results are in good agreement with the theoretical analysis. The EIT-like effect can significantly reduce the group velocity near the edge of the square profile transparent window. We believe that the counter-propagating waves coupling mechanism is particularly beneficial for the realization of active manipulation of slow light devices (such as delay lines) required in the conventional EIT scheme. In the vicinity of the transparency peak, we can obtain a large group delay, may gain more significant potential applications in slow-light transmission and optical storage.
In this work, using finite-difference time-domain method, we propose and numerically demonstrate a novel way to achieve electromagnetically induced transparency (EIT) phenomenon in the reflection spectrum by stacking two different types of coupling effect among different elements of the designed metamaterial. Compared with the conventional EIT-like analogues coming from only one type of coupling effect between bright and dark meta-atoms on the same plane, to our knowledge the novel approach is the first to realize the optically active and precise control of the wavelength position of EIT-like phenomenon using optical metamaterials. An on-to-off dynamic control of the EIT-like phenomenon also can be achieved by changing the refractive index of the dielectric substrate via adjusting an optical pump pulse. Furthermore, in near infrared region, the metamaterial structure can be operated as an ultra-high resolution refractive index sensor with an ultra-high figure of merit (FOM) reaching 3200, which remarkably improve the FOM value of plasmonic refractive index sensors. The novel approach realizing EIT-like spectral shape with easy adjustment to the working wavelengths will open up new avenues for future research and practical application of active plasmonic switch, ultra-high resolution sensors and active slow-light devices.