Massachusetts Institute of Technology

Pendar Technologies, LLC

Harvard College

Anish K Goyal

Laurent Diehl

Christian Pfluegl

Tso Yee Fan

Antonio Sanchez-Rubio

Christine A Wang

Mark Francis Witinski

Federico Capasso

Mikhail A Belkin

George W Turner

Daniel J Ripin

Benjamin G Lee

John Hybl

Photonic integrated circuits (PICs) are based on quantum cascade (QC) structures. In embodiment methods and corresponding devices, a QC layer in a wave confinement region of an integrated multi-layer semiconductor structure capable of producing optical gain is depleted of free charge carriers to create a low-loss optical wave confinement region in a portion of the structure. Ion implantation may be used to create energetically deep trap levels to trap free charge carriers. Other embodiments include modifying a region of a passive, depleted QC structure to produce an active region capable of optical gain. Gain or loss may also be modified by partially depleting or enhancing free charge carrier density. QC lasers and amplifiers may be integrated monolithically with each other or with passive waveguides and other passive devices in a self-aligned manner. Embodiments overcome challenges of high cost, complex fabrication, and coupling loss involved with material re-growth methods.

Methods for forming photonic integrated circuits based on quantum cascade structures

Photonic integrated circuits based on quantum cascade structures

A laser source based on a quantum cascade laser array (QCL), wherein the outputs of at least two elements in the array are collimated and overlapped in the far field using an external diffraction grating and a transform lens.

Wavelength beam combining of quantum cascade laser arrays

A solid-state gain element including a thin doped region in which an optical signal propagates through the thin doped region at a large angle with respect to the normal to the thin doped region, reflects at a boundary of the thin doped region, and passes through the thin doped region again. An optical pump beam propagates through the thin doped region also at a large angle with respect to the normal to the thin doped region. In one example, the gain element and source of the pump beam are configured such that there is total internal reflection of the pump beam at the boundary of the thin doped region for a second pumping pass through the thin doped region. In another example, an elliptically symmetric laser beam is used to create a circularly symmetric gain region in the thin doped region.

Grazing-incidence-disk laser element

A semiconductor laser operating in the mid-infrared region is described. In one particular embodiment, the semiconductor laser is provided having first and second cladding layers consisting essentially of GaSb that surround an active core, wherein the index of refraction of the first and second cladding layers is less than but close to the index of refraction of active core. The semiconductor laser in accordance with this invention has a low divergence angle with a high power efficiency. In an alternate embodiment, the semiconductor laser is provided having first and second cladding layers consisting essentially of Al Ga As Sb that surround the active core with an aluminum mole fraction between 0 and 25 percent. The index of refraction of the first and second cladding layers consisting essentially of Al Ga As Sb can be adjusted to match a variety of types of active cores and to provide a pre-determined divergence.

GaSb-clad mid-infrared semiconductor laser

An external-resonator laser system having multiple laser elements is configured to permit each laser to undergo individual amplification notwithstanding optical beam combination. In this way, overall output power may be scaled in a desired fashion, depending on the selected characteristics of the optical amplifier elements. To achieve additional power, each of the amplifiers may implemented as a phased array. Viewed more generally, a phased-array configuration affords beam combining in two stages, with each contributing input source itself composed of multiple sources whose outputs have been combined. If each phased-array source emits at a different wavelength, this design offers a multi-wavelength output whose power level may be scaled in accordance with the number and character of the devices forming each phased array.

High power, spectrally combined laser systems and related methods

Growing community of inventors

Cambridge, MA, United States of America

Anish K Goyal