Abstract: 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.

Abstract: A chip system and method includes a photonics chip and an electrical integrated circuit (IC) flip-chip coupled to the photonics chip to form an optochip. The IC or the photonics chip includes an array of bond pads for attachment to the other. The optochip has an array of bond pads for subsequent attachment to a carrier where the photonics chip includes an exposed edge to connect with at least one waveguide.

Abstract: 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.

Abstract: 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.

Abstract: A mid infrared spectrometer comprises a high brightness broadband source that generates an output with a broad spectral range in the order of hundreds of wave numbers, a wavelength dispersive element and a detector. In one embodiment, the source comprises an array of semiconductor laser devices operating simultaneously. Each device emits light at wavelength different from the wavelengths emitted by the other devices in the array and the devices are arranged so that the combined output continuously covers the broad spectral range. In another embodiment, each of the lasers in the array is a quantum cascade laser device. In still another embodiment, the quantum cascade laser devices in the array are operated in the regime of Risken-Nummedal-Graham-Haken (RNGH) instabilities. In yet another embodiment, each of the lasers in the array is a mode-locked quantum cascade laser device.

Abstract: 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).

Abstract: 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).