Abstract: 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.

Abstract: 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.

Abstract: 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.