@article{mehta_chien_lei_gundogdu_chang_so_2024, title={Hybrid Laser Cavity Design for Improved Photon Lifetime and Performance}, volume={36}, ISSN={["1941-0174"]}, DOI={10.1109/LPT.2024.3374261}, abstractNote={We report an optical cavity design that combines a distributed feedback (DFB) cavity as the primary feedback element for lasing with a silver mirror acting as a Fabry-Pérot cavity for broadband reflection and mode confinement. To evaluate the design, we studied the effects of the silver mirror by excluding the DFB cavity and compared its amplified spontaneous emission (ASE) properties with the sample without the mirror. In the structure with the mirror, the gain medium undergoes ASE at an excitation fluence of $17.5\,\,\mathrm { {\mu J c}}\mathrm {m}^{\mathrm {-2}}$ compared to $37\,\,\mathrm { {\mu J c}}\mathrm {m}^{\mathrm {-2}}$ for the sample without the mirror. This lower ASE threshold is attributed to enhanced mode confinement and photon density of states (PDOS) from the silver mirror increasing the cavity photon lifetime ( $ {\tau }_{\mathrm {c}}\mathrm {)}$ . Using this hybrid cavity, a multimode optically pumped laser with a threshold of $42\,\,\mathrm { {\mu J c}}\mathrm {m}^{\mathrm {-2}}$ is demonstrated. This hybrid cavity design offers an effective solution that can be readily applied to other thin film-based laser devices.}, number={7}, journal={IEEE PHOTONICS TECHNOLOGY LETTERS}, author={Mehta, Yash and Chien, Kun-Chieh and Lei, Lei and Gundogdu, Kenan and Chang, Chih-Hao and So, Franky}, year={2024}, month={Apr}, pages={516–519} }
@article{moon_mehta_gundogdu_so_gu_2023, title={Metal-Halide Perovskite Lasers: Cavity Formation and Emission Characteristics}, volume={7}, ISSN={["1521-4095"]}, DOI={10.1002/adma.202211284}, abstractNote={AbstractHybrid metal‐halide perovskites (MHPs) have shown remarkable optoelectronic properties as well as facile and cost‐effective processability. With the success of MHP solar cells and light‐emitting diodes, MHPs have also exhibited great potential as gain media for on‐chip lasers. However, to date, stable operation of optically pumped MHP lasers and electrically driven MHP lasers—an essential requirement for MHP laser's insertion into chip‐scale photonic integrated circuits—is not yet demonstrated. The main obstacles include the instability of MHPs in the atmosphere, rudimentary MHP laser cavity patterning methods, and insufficient understanding of emission mechanisms in MHP materials and cavities. This review aims to provide a detailed overview of different strategies to improve the intrinsic properties of MHPs in the atmosphere and to establish an optimal MHP cavity patterning method. In addition, this review discusses different emission mechanisms in MHP materials and cavities and how to distinguish them.}, journal={ADVANCED MATERIALS}, author={Moon, Jiyoung and Mehta, Yash and Gundogdu, Kenan and So, Franky and Gu, Qing}, year={2023}, month={Jul} }
@article{biliroglu_findik_mendes_seyitliyev_lei_dong_mehta_temnov_so_gundogdu_2022, title={Room-temperature superfluorescence in hybrid perovskites and its origins}, volume={16}, ISSN={["1749-4893"]}, url={https://doi.org/10.1038/s41566-022-00974-4}, DOI={10.1038/s41566-022-00974-4}, number={4}, journal={NATURE PHOTONICS}, publisher={Springer Science and Business Media LLC}, author={Biliroglu, Melike and Findik, Gamze and Mendes, Juliana and Seyitliyev, Dovletgeldi and Lei, Lei and Dong, Qi and Mehta, Yash and Temnov, Vasily V. and So, Franky and Gundogdu, Kenan}, year={2022}, month={Apr}, pages={324-+} }
@article{fu_mehta_chen_lei_zhu_barange_dong_yin_mendes_he_et al._2021, title={Directional Polarized Light Emission from Thin‐Film Light‐Emitting Diodes}, volume={33}, ISSN={0935-9648 1521-4095}, url={http://dx.doi.org/10.1002/adma.202006801}, DOI={10.1002/adma.202006801}, abstractNote={AbstractLight‐emitting diodes (LEDs) with directional and polarized light emission have many photonic applications, and beam shaping of these devices is fundamentally challenging because they are Lambertian light sources. In this work, using organic and perovskite LEDs (PeLEDs) for demonstrations, by selectively diffracting the transverse electric (TE) waveguide mode while suppressing other optical modes in a nanostructured LED, the authors first demonstrate highly directional light emission from a full‐area organic LED with a small divergence angle less than 3° and a TE to transverse magnetic (TM) polarization extinction ratio of 13. The highly selective diffraction of only the TE waveguide mode is possible due to the planarization of the device stack by thermal evaporation and solution processing. Using this strategy, directional and polarized emission from a perovskite LED having a current efficiency 2.6 times compared to the reference planar device is further demonstrated. This large enhancement in efficiency in the PeLED is attributed to a larger contribution from the TE waveguide mode resulting from the high refractive index in perovskite materials.}, number={9}, journal={Advanced Materials}, publisher={Wiley}, author={Fu, Xiangyu and Mehta, Yash and Chen, Yi‐An and Lei, Lei and Zhu, Liping and Barange, Nilesh and Dong, Qi and Yin, Shichen and Mendes, Juliana and He, Siliang and et al.}, year={2021}, month={Jan}, pages={2006801} }
@article{fu_chen_shin_mehta_chen_barange_zhu_amoah_chang_so_2020, title={Recovering cavity effects in corrugated organic light emitting diodes}, volume={28}, ISSN={["1094-4087"]}, DOI={10.1364/OE.404412}, abstractNote={Cavity effects play an important role in determining the out-coupling efficiency of an OLED. By fabricating OLEDs on corrugated substrates, the waveguide and SPP modes can be extracted by diffraction. However, corrugation does not always lead to an enhancement in out-coupling efficiency due to the reduction of the electrode reflectance and hence the cavity effects. Based on the results of our rigorous couple-wave analysis (RCWA) simulation, we found that the cavity effects can be partially recovered using a low index Teflon layer inserted between the ITO anode and the substrate due to the enhancement of the reflectance of the corrugated electrodes. To verify the simulation results, we fabricated corrugated OLEDs having a low-index Teflon interlayer with an EQE of 36%, which is 29% higher than an optimized planar OLED. By experimentally measuring the OLED air mode dispersion, we confirm the cavity emission of a corrugated OLED is enhanced by the low index layer.}, number={21}, journal={OPTICS EXPRESS}, author={Fu, Xiangyu and Chen, Yi-An and Shin, Dong-Hun and Mehta, Yash and Chen, I-Te and Barange, Nilesh and Zhu, Liping and Amoah, Stephen and Chang, Chih-Hao and So, Franky}, year={2020}, month={Oct}, pages={32214–32225} }