Massachusetts Institute of Technology

Leslie Kolodziejski

Gale Petrich

John Dimitris Joannopoulos

Shanhui Fan

Alexei A Erchak

Steven G Johnson

Erich P Ippen

Pierre R Villeneuve

Solomon Assefa

Franz Xaver Kaertner

Elefterios Lidorikis

Hermann A Haus

Peter Bienstman

Sheila Tandon

Daniel J Ripin

Michelle L Povinelli

Matthew E Grein

Erik R Thoen

Elisabeth M Koontz

Orit Shamir

Reginald E Bryant

A method of forming a buried oxide/crystalline III-V semiconductor dielectric stack is presented. The method includes providing a substrate and forming a layered structure on the substrate comprising of layers of different materials, one of the different materials is selected to be an oxidizable material to form one or more buried low index oxide layers. A first sequence of oxidizing steps are performed on the layered structure by exposing the edges of the layered structure to a succession of temperature increases in the presence of steam from an initial temperature to the desired oxidation temperature for a time interval equal to the sum of the time intervals of the succession of temperature increases. Also, the method includes performing a second sequential oxidizing step with steam on the layered structure at the specific oxidation temperature for a specific time interval. Furthermore, the method includes performing a final sequence of oxidizing steps on the structure by ramping down from the desired oxidation temperature to a final temperature when the oxidizing material is completely oxidized to form the one or more buried low index oxide layers.

Integration of buried oxide layers with crystalline layers

An optical modulator is provided. The optical modulator includes a ridge-shaped active region comprising a plurality of alternating high and low index layers. The ridge-shaped active region is used to confine a selective optical mode for optical modulation. A plurality of oxidized layers positioned so as to confine the selective optical mode in the middle region of the ridge-shaped active region. The oxidized layers enable the optical modulator to withstand high operating voltages both in reverse and forward bias without concern of breakdown or carrier loss.

Semiconductor-based broadband modulators

A nano-electromechanical optical switch includes an input optical waveguide that is provided with an optical signal. At least two output optical waveguides are coupled to the input optical waveguide. The deflection of the input optical waveguide aligns with one of either of the two output optical waveguides so as to allow transmission of the optical signal to one of either of the two output optical waveguides.

Nano-electromechanical high-index contrast

A coupling element includes a first stage having a dielectric waveguide that is transitioned to a waveguide having a sequence of resonators with a fixed period. A second stage transitions the waveguide to a photonic crystal waveguide by gradually bringing closer at an angle the cladding bulk of the photonic crystal to the waveguide.

Waveguide coupling into photonic crystal waveguides

A photonic circuit includes a tunable drop filter arrangement that includes a plurality of resonators. The drop filter arrangement is tuned to remove a selected frequency from an input data stream from a waveguide. A wavelength sensor coupled to the drop filter to monitor the selected frequency to which the drop filter arrangement has been tuned. A tunable laser presents a new signal of a defined frequency indicative of a signal to be added to the input data stream. A modulator coupled to the tunable laser for receiving the new signal and forming a modulated signal. An add filter arrangement coupled to the modulator for receiving the modulated signal and adding the modulated signal to the data stream.

Tunable optical add/drop multiplexer with multi-function optical amplifiers

Systems and methods for enhancing the stability of a mode-locked laser's output are disclosed. The laser systems include a mode-locking element that mode-locks the laser's output, and a semiconductor element. The semiconductor element produces a loss at the laser's operative wavelength that increases as pulse energy increases, thereby enhancing the stability of the mode-locked output. The semiconductor elements can be used to enhance stability of both passively and actively mode-locked laser systems.

Semiconductor elements for stabilizing laser output

An input light-coupling device comprising a dielectric layer containing a pattern of dielectric contrast distributed in at least two dimensions. The pattern of dielectric contrast, which may or may not be periodic, is designed to facilitate coupling to the dielectric layer of electromagnetic radiation. The electromagnetic radiation may be propagating within a surrounding medium of lower dielectric constant than that of said dielectric layer, input at directions including normal incidence from which light cannot typically couple to the dielectric layer without the presence of the pattern of dielectric contrast. The input light may constitute an optical signal propagating in an optical fiber or in free space. Light that is in-coupled may be directed in as many directions as dictated by the symmetry of the pattern of dielectric contrast. The dielectric layer may contain output waveguides surrounding the input coupling structure. The light coupling structure may be fabricated in a dielectric layer separated from a high-dielectric substrate by a low-dielectric layer to avoid losses of the input signal to the substrate. A mirror comprising either a reflective material or alternating layers of high and low dielectric material may be disposed between the low-dielectric layer and the substrate to enhance the total input coupling to the dielectric layer containing the input coupling structure.

Input light coupler using a pattern of dielectric contrast distributed in at least two dimensions

A tunable electromagnetic field frequency filter having an input waveguide which carries a signal including at least one desired frequency, and an output waveguide. A resonator-system is coupled to the input and output waveguides and is operable for the selective transfer of the at least one desired frequency to the output waveguide. The resonator-system supports at least two system modes, and includes at least three reflectors with at least two different reflectivity spectra. At least one of the reflectivity spectra is tuned such that at least two of the system-modes have substantially the same frequency when the transfer occurs substantially.

Tunable add/drop filter using side-coupled resonant tunneling

A composite photonic crystal structure comprising a guide crystal configured in a lane having a dielectric periodicity in at least a first direction in the plane; and barrier crystals configured above and below the guide crystal to confine light within the guide crystal, the barrier crystals having a dielectric periodicity in at least a second direction not in the plane. In another embodiment, there is provided a composite photonic crystal structure comprising a guide crystal configured in a plane having a dielectric periodicity in at least one dimension; and a barrier crystal configured adjacent the guide crystal to confine light within the guide crystal, the barrier crystal having a dielectric periodicity in at least two dimensions.

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Belmont, MA, United States of America

Leslie Kolodziejski