Massachusetts Institute of Technology

Ofer Shapira

John Dimitris Joannopoulos

Yoel Fink

Marin Soljacic

Bo Zhen

Fabien Sorin

Ayman F Abouraddy

Mehmet Bayindir

Wenjun Qiu

Chia Wei Hsu

Jerimy R Arnold

Alexander Stolyarov

Nicholas D Orf

Song-Liang Chua

Jeongwon Lee

Dursen Saygin Hinczewski

Lei Wei

Jean Francois Viens

Sylvain Danto

Ken Kuriki

Jeremy R Arnold

Fabien Soren

Marin Soljaic

Transparent displays enable many useful applications, including heads-up displays for cars and aircraft as well as displays on eyeglasses and glass windows. Unfortunately, transparent displays made of organic light-emitting diodes are typically expensive and opaque. Heads-up displays often require fixed light sources and have limited viewing angles. And transparent displays that use frequency conversion are typically energy inefficient. Conversely, the present transparent displays operate by scattering visible light from resonant nanoparticles with narrowband scattering cross sections and small absorption cross sections. More specifically, projecting an image onto a transparent screen doped with nanoparticles that selectively scatter light at the image wavelength(s) yields an image on the screen visible to an observer. Because the nanoparticles scatter light at only certain wavelengths, the screen is practically transparent under ambient light. Exemplary transparent scattering displays can be simple, inexpensive, scalable to large sizes, viewable over wide angular ranges, energy efficient, and transparent simultaneously.

Methods and apparatus for transparent display using scattering nanoparticles

Disclosed herein are transparent color displays with nanoparticles made with nonlinear materials and/or designed to exhibit optical resonances. These nanoparticles are embedded in or hosted on a transparent substrate, such as a flexible piece of clear plastic or acrylic. Illuminating the nanoparticles with invisible light (e.g., infrared or ultraviolet light) causes them to emit visible light. For example, a rare-earth doped nanoparticle may emit visible light when illuminated simultaneoulsy with a first infrared beam at a first wavelength &#x3bb;and a second infrared beam at a second wavelength &#x3bb;. And a frequency-doubling nanoparticle may emit visible light when illuminated with a single infrared beam at the nanoparticle's resonant frequency. Selectively addressing these nanoparticles with appropiately selected pump beams yields visible light emitted from the nanoparticles hosted by the transparent substrate in a desired pattern.

Methods and apparatus for transparent display using up-converting nanoparticles

Disclosed herein is a system for stimulating emission from at least one an emitter, such as a quantum dot or organic molecule, on the surface of a photonic crystal comprising a patterned dielectric substrate. Embodiments of this system include a laser or other source that illuminates the emitter and the photonic crystal, which is characterized by an energy band structure exhibiting a Fano resonance, from a first angle so as to stimulate the emission from the emitter at a second angle. The coupling between the photonic crystal and the emitter may result in spectral and angular enhancement of the emission through excitation and extraction enhancement. These enhancement mechanisms also reduce the emitter's lasing threshold. For instance, these enhancement mechanisms enable lasing of a 100 nm thick layer of diluted organic molecules solution with reduced threshold intensity. This reduction in lasing threshold enables more efficient organic light emitting devices and more sensitive molecular sensing.

Excitation enhancement and extraction enhancement with photonic crystals

An organic dye laser produces a continuous-wave (cw) output without any moving parts (e.g., without using flowing dye streams or spinning discs of solid-state dye media to prevent photobleaching) and with a pump beam that is stationary with respect to the organic dye medium. The laser's resonant cavity, organic dye medium, and pump beam are configured to excite a lasing transition over a time scale longer than the associated decay lifetimes in the organic dye medium without photobleaching the organic dye medium. Because the organic dye medium does not photobleach when operating in this manner, it may be pumped continuously so as to emit a cw output beam. In some examples, operation in this manner lowers the lasing threshold (e.g., to only a few Watts per square centimeter), thereby facilitating electrical pumping for cw operation.

Continuous-wave organic dye lasers and methods

Fiber draw synthesis process. The process includes arranging reactants in the solid state in proximate domains within a fiber preform. The preform is fluidized at a temperature below the melting temperature of the reactants. The fluidized preform is drawn into a fiber thereby bringing the reagents in the proximate domains into intimate contact with one another resulting in a chemical reaction between the reactants thereby synthesizing a compound within the fiber. The reactants may be dissolved or mixed in a host material within the preform. In a preferred embodiment, the reactants are selenium and zinc.

Fiber draw synthesis

The laser includes an optical fiber including a cavity containing a microfluidic gain medium bounded by a composite structure of alternating layers of high and low index materials forming an axially invariant, rotationally symmetric photonic bandgap cavity. The optical fiber also includes at least one microfluidic channel containing liquid crystal modulators in the fiber cladding extending in an axial direction and further includes a pair of electrodes flanking the microfluidic channel. An electrical potential across the pair of electrodes will rotate the liquid crystal molecules to rotate the linearly polarized state of light emitted from the cavity. An external linear polarizer is disposed around the fiber to modulate azimuthal laser intensity distribution.

Microfluidic radial fiber laser utilizing an external polarizer to modulate its azimuthal intensity distribution

There is provided a thermal sensing fiber grid, including a plurality of rows and columns of thermal sensing fibers, each of which includes a semiconducting element that has a fiber length and that is characterized by a bandgap energy corresponding to a selected operational temperature range of the fiber in which there can be produced a change in thermally-excited electronic charge carrier population in the semiconducting element in response to a temperature change in the selected temperature range. There is included at least one pair of conducting electrodes in contact with the semiconducting element along the fiber length, and an insulator along the fiber length. An electronic circuit is provided for and connected to each thermal sensing fiber for producing an indication of thermal sensing fiber grid coordinates of a change in ambient temperature.

Thermal sensing fiber devices

In one aspect, the disclosure features an article, including a fiber waveguide extending along a waveguide axis, the fiber waveguide including a core extending along the waveguide axis and a confinement region surrounding the core. The confinement region is configured to guide radiation at a first wavelength, &#x3bb;, along the waveguide axis and is configured to transmit at least some of the radiation at a second wavelength, &#x3bb;, incident on the confinement region along a path, where &#x3bb;and &#x3bb;are different. The core includes a core material selected to interact with radiation at &#x3bb;to produce radiation at &#x3bb;.

Surface-emitting fiber laser

There is provided a feedback-controlled self-heat-monitoring fiber, including an insulator having a fiber length with at least one metal-semiconductor-metal thermal sensing element along the fiber length and disposed at a position in a cross section of the fiber for sensing changes in fiber temperature. An electronic circuit is connected to the thermal sensing element for indicating changes in fiber temperature. A controller is connected for controlling optical transmission through an optical transmission element, that is disposed along the fiber length, in response to indications of changes in fiber temperature.

There is provided a thermal sensing fiber including a semiconducting element having a fiber length and characterized by a bandgap energy corresponding to a selected operational temperature range for the fiber in which there can be produced a change in thermally-excited electronic charge carrier population in the semiconducting element in response to a temperature change in the selected temperature range. At least one pair of conducting electrodes is provided in contact with the semiconducting element along the fiber length, and an insulator is provided along the fiber length.

The invention provides an optical fiber photodetector including a photoconductive element, such as a semiconducting element, having a fiber length. The semiconducting element is characterized as a non-composite material in at least one fiber direction. At least one pair of conducting electrodes is in contact with the semiconducting element along the fiber length, and an insulator is provided along the fiber length. An optical resonator can be disposed along the fiber length and along a path of illumination to the semiconducting element. The resonator is dimensioned to substantially reflect all illumination wavelengths except for a prescribed range of wavelengths transmitted to the semiconducting element. The fiber photodetector can be arranged in a photodetecting fiber grid, photodetecting fiber fabric, or other configuration for detecting incident illumination.

Growing community of inventors

Cambridge, MA, United States of America

Ofer Shapira