More Like this

1. Single Mode Supersymmetric Laser Array

   https://doi.org/10.1364/CLEO_QELS.2018.FM4E.7  

   Hokmabadi, Mohammad P.; Faryadras, Sanaz; El-Ganainy, Ramy; Christodoulides, Demetrios N.; Khajavikhan, Mercedeh (July 2018, CLEO: QELS_Fundamental Science 2018)

   Multimode emission adversely affects phased-locked laser arrays resulting in chaotic behaviors. Utilizing optical supersymmetry, we experimentally demonstrate a single mode laser array where a superpartner array eliminates undesired higher order transverse modes. 

   more » « less
2. Mantle Cloaking for Decoupling of Interleaved Phased Antenna Arrays in 5G Applications

   S. Pawar, H. M. (September 2020, METANANO-2020)

   null (Ed.)

   The concept of mantle cloaking is applied to suppress the undesired cross-coupling among the antenna elements of two tightly spaced and interleaved phased antenna arrays used in 5G wireless applications, which in turn enhances the radiation characteristics of the arrays. It is demonstrated that the specifically designed metasurface cloaks decouple the antenna elements of two different arrays and enable to restore the original radiation patterns of the isolated arrays, such that the antenna arrays placed in close proximity of each other can radiate independently for a wide range of beam scanning angles. This paper illustrates microstrip antenna arrays with elliptically shaped metasurface cloaks integrated in printed technology. The simulation results validate the fact that by encasing the elements of the arrays with their respective cloaks, it is not only possible to eliminate the cross coupling but also to restore the radiation properties of the antenna arrays within the frequency bands of their operation. 

   more » « less
3. Cloaking and Decoupling of Interleaved Microstrip Monopole Arrays at 28 GHz and 39 GHz Using Elliptical Metasurfaces for 5G Wireless Applications

   S. Pawar, S. Mastromatteo (July 2020, 2020 IEEE AP-S/URSI Conference)

   null (Ed.)

   Two tightly spaced, interleaved microstrip monopole antenna arrays operating at microwave frequencies are decoupled by employing mantle cloaking method. We use elliptical metasurfaces specifically tailored for the cross-coupled elements of the distinct arrays and show that by wrapping each antenna element with the metasurface cloak, the undesired cross-coupling between the elements at frequencies 28 GHz and 39 GHz is eliminated, restoring their radiation patterns as if the arrays were isolated from each other. In this paper, the cloaking and decoupling effect is scrutinized and evaluated to improve the functionality of the coupled arrays in terms of their radiation patterns and realized gain, when all the antenna elements are excited simultaneously. Consequently, the monopole antenna arrays, even though placed in close proximity, can radiate independently for a wide range of beam scanning angles. 

   more » « less
4. Room temperature electrically pumped topological insulator lasers

   https://doi.org/10.1038/s41467-021-23718-4  

   Choi, Jae-Hyuck; Hayenga, William E.; Liu, Yuzhou G.; Parto, Midya; Bahari, Babak; Christodoulides, Demetrios N.; Khajavikhan, Mercedeh (December 2021, Nature Communications)

   null (Ed.)

   Abstract Topological insulator lasers (TILs) are a recently introduced family of lasing arrays in which phase locking is achieved through synthetic gauge fields. These single frequency light source arrays operate in the spatially extended edge modes of topologically non-trivial optical lattices. Because of the inherent robustness of topological modes against perturbations and defects, such topological insulator lasers tend to demonstrate higher slope efficiencies as compared to their topologically trivial counterparts. So far, magnetic and non-magnetic optically pumped topological laser arrays as well as electrically pumped TILs that are operating at cryogenic temperatures have been demonstrated. Here we present the first room temperature and electrically pumped topological insulator laser. This laser array, using a structure that mimics the quantum spin Hall effect for photons, generates light at telecom wavelengths and exhibits single frequency emission. Our work is expected to lead to further developments in laser science and technology, while opening up new possibilities in topological photonics. 

   more » « less
5. Continuous recoil-driven lasing and cavity frequency pinning with laser-cooled atoms

   https://doi.org/10.1038/s41567-025-02854-4  

   Schäfer, Vera_M; Niu, Zhijing; Cline, Julia_R_K; Young, Dylan_J; Song, Eric_Yilun; Ritsch, Helmut; Thompson, James_K (April 2025, Nature Physics)

   Abstract Laser-cooled gases of atoms interacting with the field of an optical cavity are a versatile tool for quantum sensing and the simulation of quantum systems. These systems can exhibit phenomena such as self-organization phase transitions, lasing mechanisms, squeezed states and protection of quantum coherence. However, investigations of these phenomena typically occur in a discontinuous manner due to the need to reload atomic ensembles. Here we demonstrate hours-long continuous lasing from laser-cooled⁸⁸Sr atoms loaded into a ring cavity. The required inversion to produce lasing arises from inversion in the atomic-momentum degrees of freedom, which is linked to the self-organization phase transitions and collective atomic recoil lasing observed previously only in a cyclic fashion. We find that over a broad parameter range, the sensitivity of the lasing frequency to changes in cavity frequency is significantly reduced due to an atomic loss mechanism, suggesting a potential approach for mitigating low-frequency cavity noise. Our findings open opportunities for continuous cavity quantum electrodynamics experiments and robust and continuous super-radiant lasers. 

   more » « less