Harvard College

Pendar Technologies, LLC

Massachusetts Institute of Technology

Eos Photonics, Inc.

Laurent Diehl

Christian Pfluegl

Mark Francis Witinski

Federico Capasso

Mikhail A Belkin

Anish K Goyal

Benjamin G Lee

Christine A Wang

Christian Pflugl

Antonio Sanchez-Rubio

C Kumar N Patel

Arkadiy Lyakh

Richard Maulini

Alexei Tsekoun

Christian Pflügl

Qijie Wang

Ross M Audet

James B MacArthur

A spectroscopy system includes an array of quantum cascade lasers (QCLs) that emits an array of non-coincident laser beams. A lens array coupled to the QCL array substantially collimates the laser beams, which propagate along parallel optical axes towards a sample. The beams remain substantially collimated over the lens array's working distance, but may diverge when propagating over longer distances. The collimated, parallel beams may be directed to/through the sample, which may be within a sample cell, flow cell, multipass spectroscopic absorption cell, or other suitable holder. Alternatively, the beams may be focused to a point on, near, or within the target using a telescope or other suitable optical element(s). When focused, however, the beams remain non-coincident; they simply intersect at the focal point. The target transmits, reflects, and/or scatters this incident light to a detector, which transduces the detected radiation into an electrical signal representative of the target's absorption or emission spectrum.

Spectroscopy systems and methods using quantum cascade laser arrays with lenses

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

The present technology relates to a fast and efficient heating element based on a thick heterostructure which is monolithically integrated in close proximity to one or more components of a photonic or an electronic circuit. Inventive embodiments also relate to methods of use illustrative heating elements to control or tune the characteristics of the electronic or photonic component(s). Inventive embodiments may be particularly useful in the fast spectral tuning of the emission wavelength of single mode QCLs.

Methods and apparatus for temperature tuning of semiconductor lasers

Methods and apparatus for improved single-mode selection in a quantum cascade laser. In one example, a distributed feedback grating incorporates both index-coupling and loss-coupling components. The loss-coupling component facilitates selection of one mode from two possible emission modes by periodically incorporating a thin layer of 'lossy' semiconductor material on top of the active region to introduce a sufficiently large loss difference between the two modes. The lossy layer is doped to a level sufficient to induce considerable free-carrier absorption losses for one of the two modes while allowing sufficient gain for the other of the two modes. In alternative implementations, the highly-doped layer may be replaced by other low-dimensional structures such as quantum wells, quantum wires, and quantum dots with significant engineered intraband absorption to selectively increase the free-carrier absorption losses for one of multiple possible modes so as to facilitate single-mode operation.

Methods and apparatus for single-mode selection in quantum cascade lasers

A quantum cascade laser utilizing non-resonant extraction design having a multilayered semiconductor with a single type of carrier; at least two final levels (and) for a transition down from level; an energy spacing Egreater than E; an energy spacing Eof about 100 meV; and an energy spacing Eabout equal to E. The carrier wave function for leveloverlaps with the carrier wave function for level. Likewise, the carrier wave function for level' overlaps with the carrier wave function for level. In a second version, the basic design also has an energy spacing Eof about 90 meV, and levelsand&#x2032; do not have to be spatially close to each other, provided that levelhas significant overlap with both these levels. In a third version, there are at least three final levels (, and) for a transition down from level. Each of the levels, andhas a non-uniform squared wave function distribution.

Quantum cascade laser

A broadly tunable single-mode infrared laser source based on semiconductor lasers. The laser source has two parts: an array of closely-spaced DFB QCLs (or other semiconductor lasers) and a controller that can switch each of the individual lasers in the array on and off, set current for each of the lasers and, and control the temperature of the lasers in the array. The device can be used in portable broadband sensors to simultaneously detect a large number of compounds including chemical and biological agents. A microelectronic controller is combined with an array of individually-addressed DFB QCLs with slightly different DFB grating periods fabricated on the same broadband (or multiple wavelengths) QCL material. This allows building a compact source providing narrow-line broadly-tunable coherent radiation in the Infrared or Terahertz spectral range (as well as in the Ultraviolet and Visible spectral ranges, using semiconductor lasers with different active region design). The performance (tuning range, line width, power level) is comparable to that of external grating tunable semiconductor lasers, but the proposed design is much smaller and much easier to manufacture.

Broadly tunable single-mode quantum cascade laser sources and sensors

Growing community of inventors

Cambridge, MA, United States of America

Laurent Diehl