Recursos de colección

Caltech Authors (163.728 recursos)

Repository of works by Caltech published authors.

Group = Kavli Nanoscience Institute

Mostrando recursos 1 - 20 de 245

  1. Gigahertz-repetition-rate soliton microcombs

    Suh, Myoung-Gyun; Vahala, Kerry
    Soliton microcombs with repetition rates as low as 1.86 GHz are demonstrated, thereby entering a regime more typical of table–top combs. Low rates are important in spectroscopy and relax requirements on comb processing electronics.

  2. Bridging ultra-high-Q devices and photonic circuits

    Yang, Ki Youl; Oh, Dong Yoon; Lee, Seung Hoon; Yang, Qi-Fan; Yi, Xu; Vahala, Kerry
    Optical microcavities are essential in numerous technologies and scientific disciplines. However, their application in many areas relies exclusively upon discrete microcavities in order to satisfy challenging combinations of ultra-low-loss performance (high cavity-Q-factor) and cavity design requirements. Indeed, finding a microfabrication bridge connecting ultra-high-Q device functions with micro and nanophotonic circuits has been a long-term priority of the microcavity field. Here, an integrated ridge resonator having a record Q factor over 200 million is presented. Its ultra-low-loss and flexible cavity design brings performance that has been the exclusive domain of discrete silica and crytalline microcavity devices to integrated systems. Two distinctly...

  3. Bridging ultra-high-Q devices and photonic circuits

    Yang, Ki Youl; Oh, Dong Yoon; Lee, Seung Hoon; Yang, Qi-Fan; Yi, Xu; Vahala, Kerry
    Optical microcavities are essential in numerous technologies and scientific disciplines. However, their application in many areas relies exclusively upon discrete microcavities in order to satisfy challenging combinations of ultra-low-loss performance (high cavity-Q-factor) and cavity design requirements. Indeed, finding a microfabrication bridge connecting ultra-high-Q device functions with micro and nanophotonic circuits has been a long-term priority of the microcavity field. Here, an integrated ridge resonator having a record Q factor over 200 million is presented. Its ultra-low-loss and flexible cavity design brings performance that has been the exclusive domain of discrete silica and crytalline microcavity devices to integrated systems. Two distinctly...

  4. Complex wavefront engineering with disorder-engineered metasurfaces

    Jang, Mooseok; Horie, Yu; Shibukawa, Atsushi; Brake, Joshua; Liu, Yan; Kamali, Seyedeh Mahsa; Arbabi, Amir; Ruan, Haowen; Faraon, Andrei; Yang, Changhuei
    Recently, complex wavefront engineering with disordered media has demonstrated optical manipulation capabilities beyond those of conventional optics. These capabilities include extended volume, aberration-free focusing and subwavelength focusing via evanescent mode coupling. However, translating these capabilities to useful applications has remained challenging as the input-output characteristics of the disordered media (P variables) need to be exhaustively determined via O(P) measurements. Here, we propose a paradigm shift where the disorder is specifically designed so that its exact characteristics are known, resulting in an a priori determined transmission matrix that can be utilized with only a few alignment steps. We implement this concept...

  5. Complex wavefront engineering with disorder-engineered metasurfaces

    Jang, Mooseok; Horie, Yu; Shibukawa, Atsushi; Brake, Joshua; Liu, Yan; Kamali, Seyedeh Mahsa; Arbabi, Amir; Ruan, Haowen; Faraon, Andrei; Yang, Changhuei
    Recently, complex wavefront engineering with disordered media has demonstrated optical manipulation capabilities beyond those of conventional optics. These capabilities include extended volume, aberration-free focusing and subwavelength focusing via evanescent mode coupling. However, translating these capabilities to useful applications has remained challenging as the input-output characteristics of the disordered media (P variables) need to be exhaustively determined via O(P) measurements. Here, we propose a paradigm shift where the disorder is specifically designed so that its exact characteristics are known, resulting in an a priori determined transmission matrix that can be utilized with only a few alignment steps. We implement this concept...

  6. Optical magnetism in planar metamaterial heterostructures

    Papadakis, Georgia T.; Fleischman, Dagny; Davoyan, Artur; Yeh, Pochi; Atwater, Harry A.
    Harnessing artificial optical magnetism has previously required complex two- and three-dimensional structures, such as nanoparticle arrays and split-ring metamaterials. By contrast, planar structures, and in particular dielectric/metal multilayer metamaterials, have been generally considered non-magnetic. Although the hyperbolic and plasmonic properties of these systems have been extensively investigated, their assumed non-magnetic response limits their performance to transverse magnetic (TM) polarization. We propose and experimentally validate a mechanism for artificial magnetism in planar multilayer metamaterials. We also demonstrate that the magnetic properties of high-index dielectric/metal hyperbolic metamaterials can be anisotropic, leading to magnetic hyperbolic dispersion in certain frequency regimes. We show that...

  7. Optical magnetism in planar metamaterial heterostructures

    Papadakis, Georgia T.; Fleischman, Dagny; Davoyan, Artur; Yeh, Pochi; Atwater, Harry A.
    Harnessing artificial optical magnetism has previously required complex two- and three-dimensional structures, such as nanoparticle arrays and split-ring metamaterials. By contrast, planar structures, and in particular dielectric/metal multilayer metamaterials, have been generally considered non-magnetic. Although the hyperbolic and plasmonic properties of these systems have been extensively investigated, their assumed non-magnetic response limits their performance to transverse magnetic (TM) polarization. We propose and experimentally validate a mechanism for artificial magnetism in planar multilayer metamaterials. We also demonstrate that the magnetic properties of high-index dielectric/metal hyperbolic metamaterials can be anisotropic, leading to magnetic hyperbolic dispersion in certain frequency regimes. We show that...

  8. Narrow-Linewidth Oxide-Confined Heterogeneously Integrated Si/III–V Semiconductor Lasers

    Wang, Huolei; Kim, Dongwan; Harfouche, Mark; Santis, Christos T.; Satyan, Naresh; Rakuljic, George; Yariv, Amnon
    We demonstrate a narrow-linewidth heterogeneously integrated Si/III-V laser, where the current confinement in the III-V structure is obtained by oxide isolation rather than by the prevailing ion-implantation technique. This method provides effective electrical isolation as well as III-V surface passivation, and a pathway for high-efficiency diode injection laser performance. This method also offers increased compatibility with potentially high-temperature annealing processes. The lasers shown here possess a threshold current of as low as 60 mA and a single-facet output power of more than 3 mW at 20 °C. A linewidth of 28 kHz at 1574.8 nm is obtained at a current...

  9. Soliton microcomb operation to 778 nm

    Yang, Q. F.; Lee, S. H.; Oh, D. Y.; Shen, B.; Wang, H.; Yang, K. Y.; Lai, Y. H.; Yi, X.; Vahala, K.
    Soliton microcombs are demonstrated at both 1064 nm and 778 nm by dispersion-engineering on-chip silica resonators. These are the shortest wavelength soliton microcombs demonstrated to date and have potential applications in optical clocks and metrology.

  10. Searching for Exoplanets Using a Microresonator Astrocomb

    Suh, Myoung-Gyun; Yi, Xu; Lai, Yu-Hung; Leifer, S.; Grudinin, Ivan S.; Vasisht, G.; Martin, Emily C.; Fitzgerald, Michael P.; Doppmann, G.; Wang, J.; Mawet, D.; Papp, Scott B.; Diddams, Scott A.; Beichman, C.; Vahala, Kerry
    Detection of weak radial velocity shifts of host stars induced by orbiting planets is an important technique for discovering and characterizing planets beyond our solar system. Optical frequency combs enable calibration of stellar radial velocity shifts at levels required for detection of Earth analogs. A new chip-based device, the Kerr soliton microcomb, has properties ideal for ubiquitous application outside the lab and even in future space-borne instruments. Moreover, microcomb spectra are ideally suited for astronomical spectrograph calibration and eliminate filtering steps required by conventional mode-locked-laser frequency combs. Here, for the calibration of astronomical spectrographs, we demonstrate an atomic/molecular line-referenced, near-infrared...

  11. Soliton Microcomb Range Measurement

    Suh, Myoung-Gyun; Vahala, Kerry
    Laser-based range measurement systems (LIDAR) are important in many application areas including autonomous vehicles, robotics, manufacturing, formation-flying of satellites, and basic science. Coherent laser ranging systems using dual frequency combs provide an unprecedented combination of long range, high precision and fast update rate. Here, dual-comb distance measurement using chip-based soliton microcombs is demonstrated. Moreover, the dual frequency combs are generated within a single microresonator as counter-propating solitons using a single pump laser. Time-of-flight measurement with 200 nm precision at 500 ms averaging time is demonstrated. Also, the dual comb method extends the ambiguity distance to 26 km despite a soliton...

  12. Angle-Multiplexed Metasurfaces: Encoding Independent Wavefronts in a Single Metasurface under Different Illumination Angles

    Kamali, Seyedeh Mahsa; Arbabi, Ehsan; Arbabi, Amir; Horie, Yu; Faraji-Dana, Mohammad Sadegh; Faraon, Andrei
    The angular response of thin diffractive optical elements is highly correlated. For example, the angles of incidence and diffraction of a grating are locked through the grating momentum determined by the grating period. Other diffractive devices, including conventional metasurfaces, have a similar angular behavior due to the fixed locations of the Fresnel zone boundaries and the weak angular sensitivity of the meta-atoms. To alter this fundamental property, we introduce angle-multiplexed metasurfaces, composed of reflective high-contrast dielectric U-shaped meta-atoms, whose response under illumination from different angles can be controlled independently. This enables flat optical devices that impose different and independent optical...

  13. Dynamically controlled Purcell enhancement of visible spontaneous emission in a gated plasmonic heterostructure

    Lu, Yu-Jung; Sokhoyan, Ruzan; Cheng, Wen-Hui; Shirmanesh, Ghazaleh Kafaie; Davoyan, Artur R.; Pala, Ragip A.; Thyagarajan, Krishnan; Atwater, Harry A.
    Emission control of colloidal quantum dots (QDs) is a cornerstone of modern high-quality lighting and display technologies. Dynamic emission control of colloidal QDs in an optoelectronic device is usually achieved by changing the optical pump intensity or injection current density. Here we propose and demonstrate a distinctly different mechanism for the temporal modulation of QD emission intensity at constant optical pumping rate. Our mechanism is based on the electrically controlled modulation of the local density of optical states (LDOS) at the position of the QDs, resulting in the modulation of the QD spontaneous emission rate, far-field emission intensity, and quantum...

  14. Dynamically controlled Purcell enhancement of visible spontaneous emission in a gated plasmonic heterostructure

    Lu, Yu-Jung; Sokhoyan, Ruzan; Cheng, Wen-Hui; Shirmanesh, Ghazaleh Kafaie; Davoyan, Artur R.; Pala, Ragip A.; Thyagarajan, Krishnan; Atwater, Harry A.
    Emission control of colloidal quantum dots (QDs) is a cornerstone of modern high-quality lighting and display technologies. Dynamic emission control of colloidal QDs in an optoelectronic device is usually achieved by changing the optical pump intensity or injection current density. Here we propose and demonstrate a distinctly different mechanism for the temporal modulation of QD emission intensity at constant optical pumping rate. Our mechanism is based on the electrically controlled modulation of the local density of optical states (LDOS) at the position of the QDs, resulting in the modulation of the QD spontaneous emission rate, far-field emission intensity, and quantum...

  15. Shock Synthesis of Five-component Icosahedral Quasicrystals

    Oppenheim, Julius; Ma, Chi; Hu, Jinping; Bindi, Luca; Steinhardt, Paul J.; Asimow, Paul D.
    Five-component icosahedral quasicrystals with compositions in the range Al_(68–73)Fe_(11–16)Cu_(10–12)Cr_(1–4)Ni_(1–2) were recently recovered after shocking metallic CuAl_5 and (Mg_(0.75)Fe_(0.25))_2SiO_4 olivine in a stainless steel 304 chamber, intended to replicate a natural shock that affected the Khatyrka meteorite. The iron in those quasicrystals might have originated either from reduction of Fe^(2+) in olivine or from the stainless steel chamber. In this study, we clarify the shock synthesis mechanism of icosahedral quasicrystals through two new shock recovery experiments. When CuAl_5 and Fe^(2+)-bearing olivine were isolated in a Ta capsule, no quasicrystals were found. However, with only metallic starting materials, numerous micron-sized five-component icosahedral...

  16. Shock Synthesis of Five-component Icosahedral Quasicrystals

    Oppenheim, Julius; Ma, Chi; Hu, Jinping; Bindi, Luca; Steinhardt, Paul J.; Asimow, Paul D.
    Five-component icosahedral quasicrystals with compositions in the range Al_(68–73)Fe_(11–16)Cu_(10–12)Cr_(1–4)Ni_(1–2) were recently recovered after shocking metallic CuAl_5 and (Mg_(0.75)Fe_(0.25))_2SiO_4 olivine in a stainless steel 304 chamber, intended to replicate a natural shock that affected the Khatyrka meteorite. The iron in those quasicrystals might have originated either from reduction of Fe^(2+) in olivine or from the stainless steel chamber. In this study, we clarify the shock synthesis mechanism of icosahedral quasicrystals through two new shock recovery experiments. When CuAl_5 and Fe^(2+)-bearing olivine were isolated in a Ta capsule, no quasicrystals were found. However, with only metallic starting materials, numerous micron-sized five-component icosahedral...

  17. Shock Synthesis of Decagonal Quasicrystals

    Oppenheimer, J.; Ma, C.; Hu, J.; Bindi, L.; Steinhardt, P. J.; Asimow, P. D.
    The Khatyrka meteorite contains both icosahedral and decagonal quasicrystals. In our previous studies, icosahedral quasicrystals have been synthesized and recovered from shock experiments at the interface between CuAl_5 and stainless steel 304 alloys. In this study, we report a new shock recovery experiment aimed at synthesizing decagonal quasicrystals similar to decagonite, natural Al_(71)Ni_(24)Fe_5. Aluminum 2024 and permalloy 80 alloys were stacked together and shocked in a stainless steel 304 recovery chamber. Abundant decagonal quasicrystals of average composition Al_(73)Ni_(19)Fe_4Cu_2Mg_(0.6)Mo_(0.4)Mn_(0.3) with traces of Si and Cr were found along the recovered interface between the Al and permalloy. The experiment also synthesized AlNiFe...

  18. Shock Synthesis of Decagonal Quasicrystals

    Oppenheim, J.; Ma, C.; Hu, J.; Bindi, L.; Steinhardt, P. J.; Asimow, P. D.
    The Khatyrka meteorite contains both icosahedral and decagonal quasicrystals. In our previous studies, icosahedral quasicrystals have been synthesized and recovered from shock experiments at the interface between CuAl_5 and stainless steel 304 alloys. In this study, we report a new shock recovery experiment aimed at synthesizing decagonal quasicrystals similar to decagonite, natural Al_(71)Ni_(24)Fe_5. Aluminum 2024 and permalloy 80 alloys were stacked together and shocked in a stainless steel 304 recovery chamber. Abundant decagonal quasicrystals of average composition Al_(73)Ni_(19)Fe_4Cu_2Mg_(0.6)Mo_(0.4)Mn_(0.3) with traces of Si and Cr were found along the recovered interface between the Al and permalloy. The experiment also synthesized AlNiFe...

  19. Shock Synthesis of Decagonal Quasicrystals

    Oppenheim, J.; Ma, C.; Hu, J.; Bindi, L.; Steinhardt, P. J.; Asimow, P. D.
    The Khatyrka meteorite contains both icosahedral and decagonal quasicrystals. In our previous studies, icosahedral quasicrystals have been synthesized and recovered from shock experiments at the interface between CuAl_5 and stainless steel 304 alloys. In this study, we report a new shock recovery experiment aimed at synthesizing decagonal quasicrystals similar to decagonite, natural Al_(71)Ni_(24)Fe_5. Aluminum 2024 and permalloy 80 alloys were stacked together and shocked in a stainless steel 304 recovery chamber. Abundant decagonal quasicrystals of average composition Al_(73)Ni_(19)Fe_4Cu_2Mg_(0.6)Mo_(0.4)Mn_(0.3) with traces of Si and Cr were found along the recovered interface between the Al and permalloy. The experiment also synthesized AlNiFe...

  20. Shock Synthesis of Decagonal Quasicrystals

    Oppenheim, J.; Ma, C.; Hu, J.; Bindi, L.; Steinhardt, P. J.; Asimow, P. D.
    The Khatyrka meteorite contains both icosahedral and decagonal quasicrystals. In our previous studies, icosahedral quasicrystals have been synthesized and recovered from shock experiments at the interface between CuAl_5 and stainless steel 304 alloys. In this study, we report a new shock recovery experiment aimed at synthesizing decagonal quasicrystals similar to decagonite, natural Al_(71)Ni_(24)Fe_5. Aluminum 2024 and permalloy 80 alloys were stacked together and shocked in a stainless steel 304 recovery chamber. Abundant decagonal quasicrystals of average composition Al_(73)Ni_(19)Fe_4Cu_2Mg_(0.6)Mo_(0.4)Mn_(0.3) with traces of Si and Cr were found along the recovered interface between the Al and permalloy. The experiment also synthesized AlNiFe...

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