Massachusetts Institute of Technology

3m Innovative Properties Company

Erich P Ippen

Franz Xaver Kaertner

John Dimitris Joannopoulos

Hermann A Haus

Leslie Kolodziejski

Poh-Boon Phua

Marin Soljacic

Shanhui Fan

Alexei A Erchak

Steven G Johnson

Gale Petrich

Christopher Richard Doerr

Michael Robert Watts

Rajeev J Ram

James Francis Brennan, Iii

Elefterios Lidorikis

James G Fujimoto

Chee Wei Wong

Mihai Ibanescu

Peter Thomas Rakich

Bryan Shawn Robinson

Rafif E Hamam

Scott A Hamilton

Evan J Reed

Eleanor L Haus, Legal Representative

Patrick C Chou

Daniel J Ripin

Michelle L Povinelli

Shelby J Savage

Jian Chen

Matthew E Grein

Solomon Assefa

Uwe Morgner

Lynn E Nelson

Kohichi R Tamura

Patrick T Callahan

Harry L T Lee

Erik R Thoen

Jorge Bravo Abad

Elisabeth M Koontz

Hyunil Byun

Dominik Pudo

Katia Shtyrkova

Reginald E Bryant

An artificial saturable absorber uses additive pulse mode-locking to enable pulse operation of an on-chip laser operation. Four different artificial saturable absorbers are disclosed. The first includes an integrated coupler, two arms each containing some implementation of the end-reflector, and a phase bias element in one arm. The second includes an integrated directional coupler, two integrated waveguide arms, and another integrated coupler as an output. The third includes an integrated birefringent element, integrated birefringent-free waveguide, and integrated polarizer. And the fourth includes a multimode waveguide that allows for different modes to propagate in such a way that the difference in the spatial distribution of intensity causes a nonlinear phase difference between the modes. These are just some examples of an on-chip fully integrated artificial saturable absorber with instantaneous recovery time that allow for generation of sub-femtosecond optical pulses at high repetition rates using passive mode-locking.

Methods and apparatus for mode-locking on-chip lasers

Disclosed is a system including an integrated silicon-based structure including a microcavity configured to receive optical energy from an input beam carrying an optical signal and absorb the optical energy by a nonlinear multi-photon absorption process. For example, the multi-photon absorption process can be two-photon absorption (TPA). The integrated silicon-based structure further includes electrodes responsive to the nonlinear multi-photon absorption process in the microcavity for producing an electronic signal indicative of the optical signal. A related method is also disclosed.

Integrated silicon-based nonlinear photodetector

Femtosecond pulse trains in waveguide lasers with high fundamental repetition rates are achieved by exploiting the nonlinearity in the waveguide. Components of the apparatus include an optical resonator, a saturable absorber for starting and stabilizing mode-locking, and a gain element. Part of the laser cavity or the entire laser cavity is made of waveguide or fiber (collectively called 'waveguide' herein). The net dispersion of the laser cavity can be anomalous. This anomalous dispersion in combination with the positive self-phase modulation nonlinearity in the waveguide creates soliton formation to shorten the pulse duration in the invented lasers. Conversely, a normal dispersive waveguide with negative self-phase modulation nonlinearity can also be used.

High-repetition-rate guided-mode femtosecond laser

A polarization controller includes a phase retarder having a rotation about an {1,0,0} axis that receives an optical signal from a waveguide structure. At least one nanoelectromechanical dielectric perturber produces &#xb1;45&#xb0; birefringent axes by placing the at least one nanoelectromechanical dielectric perturber at selective positions around the phase retarder to produce dynamic change in the effective index in one of the modes existent in an extraordinary axial direction.

Integrated polarization controllers with nano-electromechanical dielectric pertubation

A system and a method for generating terahertz (THz) radiation are provided. The system includes a photonic crystal structure comprising at least one nonlinear material that enables optical rectification. The photonic crystal structure is configured to have the suitable transverse dispersion relations and enhanced density photonic states so as to allow THz radiation to be emitted efficiently when an optical or near infrared pulse travels through the nonlinear part of the photonic crystal.

Efficient terahertz sources by optical rectification in photonic crystals and metamaterials exploiting tailored transverse dispersion relations

A PMD emulator includes at least two polarization phase plates. The rotation matrix of the at two phase plates are varied to reduce the required number of phase-plates without reducing the number of birefringent segments used.

Combinatorial polarization scramblers for many segment PMD emulator

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 PMD device includes a first stage that receives a signal and performs rotation about {1,0,0} on the signal. The first stage outputs a first signal. A second stage receives the first signal and performs a rotation about {0,0,1} on the first signal. The second stage outputs a second signal that represents the alignment the PMD of various frequencies into a common direction. A third stage receives the second signal and provides the necessary frequency dependent variable in the {1,0,0} direction to cancel the PMD in any specified frequency range.

All-frequency PMD compensator and emulator

Described is an all-optical switch that is significantly insensitive to polarization instabilities. The optical switch can be configured as an ultrafast logic gate, a switch for ultrafast communication systems or a key component of an all-optical regenerator. Performance is independent of the statistical characteristics of the data controlling the switch. The switch includes a birefringent optical channel in communication with one end of a nonlinear optical channel through a coupler and a polarization rotation mirror in communication with the other end of the nonlinear channel. An optical data pulse for controlling the switching function is provided to one port of the coupler.

Polarization-stabilized all-optical switch

A method and apparatus are provided for generating short (e.g., picosecond) pulses using a 2 section 1553 nm DBR laser without gain switching nor external modulation. The center wavelength of the DBR section is modulated at 0.5 GHz to generate a constant amplitude frequency modulated optical wave Large group velocity dispersion is then applied with a chirped fiber Bragg grating to convert the FM signal to a pulse stream.

Method and apparatus for generating frequency modulated pulses

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

A mirror system for use in generating a short duration laser pulse is disclosed. The system includes first and second double-chirped mirrors disposed along an optical path within a cavity, where the second double-chirped mirror includes an additional phase-shifting layer as compared to the first double-chirped mirror. The additional phase-shifting layer causes the mirror system during use to produce a laser pulse that is characterized by oscillations in group delay substantially reduced in amplitude in comparison to oscillations in group delay for a pulse produced by the same system without the additional phase-shifting layer.

Double-chirped mirror systems and methods

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 fiber laser for producing high energy ultrashort laser pulses, having a positive-dispersion fiber segment and a negative-dispersion fiber segment joined in series with the positive-dispersion fiber segment to form a laser cavity. With this configuration, soliton effects of laser pulse circulation in the cavity are suppressed and widths of laser pulses circulating in the cavity undergo large variations between a maximum laser pulse width and a minimum laser pulse width during one round trip through the cavity. The fiber laser also provides means for modelocking laser radiation in the laser cavity, means for providing laser radiation gain in the laser cavity, and means for extracting laser pulses from the laser cavity. Using selected positive- and negative-dispersion fiber segments, the laser cavity exhibits a net positive group velocity dispersion, and the ratio of the maximum laser pulse width to the minimum laser pulse width attained during one round trip through the cavity is greater than 5, and preferably greater than 10. The laser cavity may be configured as a linear cavity geometry, a ring cavity geometry, a figure eight geometry, or a Sagnac loop reflector geometry, among others. Preferably the ring cavity is configured to achieve unidirectional circulation of laser pulses in the ring cavity, and with this configuration, is shown to produce laser pulses having a pulse width of less than 100 fs and a pulse energy of at least 80 pJ.

Stretched-pulse fiber laser

Growing community of inventors

Belmont, MA, United States of America

Erich P Ippen