Abstract: Apparatus and methods for generating radiation via difference frequency generation (DFG). In one exemplary implementation, a quantum cascade laser (QCL) has a significant second-order nonlinear susceptibility (?(2)) integrated in an active region of the QCL. The QCL is configured to generate first radiation at a first frequency ?1, second radiation at a second frequency ?2, and third radiation at a third frequency ?3=?1??2 based on difference frequency generation (DFG) arising from the nonlinear susceptibility. In one aspect, the QCL may be configured to generate appreciable THz radiation at room temperature.

Abstract: Apparatus and methods for generating radiation via difference frequency generation (DFG). In one exemplary implementation, a quantum cascade laser (QCL) has a significant second-order nonlinear susceptibility (?(2)) integrated in an active region of the QCL. The QCL is configured to generate first radiation at a first frequency ?1, second radiation at a second frequency ?2, and third radiation at a third frequency ?3=?1??2 based on difference frequency generation (DFG) arising from the non-linear susceptibility. In one aspect, the QCL may be configured to generate appreciable THz radiation at room temperature.

Abstract: Apparatus and methods for generating radiation via difference frequency generation (DFG). In one exemplary implementation, a quantum cascade laser (QCL) has a significant second-order nonlinear susceptibility (?(2)) integrated in an active region of the QCL. The QCL is configured to generate first radiation at a first frequency ?1, second radiation at a second frequency ?2, and third radiation at a third frequency ?3=?1??2 based on difference frequency generation (DFG) arising from the non-linear susceptibility. In one aspect, the QCL may be configured to generate appreciable THz radiation at room temperature.

Abstract: Embodiments of a laser are disclosed.

Abstract: An optical device comprises a cavity resonator and an intracavity ridge waveguide. The ridge waveguide includes a monolithically integrated intersubband core region and a nonlinear mixing region (NMR). In response to external pumping energy the core region generates laser light at a first frequency and in a first transverse mode. In response to the laser light the NMR generates parametric light at a second frequency and in a second transverse mode. For phase matching the effective-refractive-index-versus-ridge-width characteristics of the modes of the laser and the parametric light intersect one another at a phase matching width and so that, at greater widths, the effective refractive index of the mode of the higher frequency light is less than that of the lower frequency light. For true phase matching the width of the ridge is made to be essentially equal to the phase matching width.

Abstract: An optical device comprises a cavity resonator and an intracavity ridge waveguide. The ridge waveguide includes a monolithically integrated intersubband core region and a nonlinear mixing region (NMR). In response to external pumping energy the core region generates laser light at a first frequency and in a first transverse mode. In response to the laser light the NMR generates parametric light at a second frequency and in a second transverse mode. For phase matching the effective-refractive-index-versus-ridge-width characteristics of the modes of the laser and the parametric light intersect one another at a phase matching width and so that, at greater widths, the effective refractive index of the mode of the higher frequency light is less than that of the lower frequency light. For true phase matching the width of the ridge is made to be essentially equal to the phase matching width.

Abstract: Infrared generation is disclosed. A first laser field having a first frequency associated with a first interband transition is generated. A second laser field having a second frequency associated with a second interband transition is generated. The generation of the first laser field occurs substantially simultaneously with the generation of the second laser field. A third laser field is generated from the first laser field and the second laser field. The third laser field has a third frequency associated with an intersubband transition. The third frequency is substantially equivalent to a difference between the second frequency and the first frequency.

Abstract: According to one embodiment, detecting radiation includes receiving a first laser drive field at a cell comprising a medium having a number of states. The first laser drive field has a frequency approximately equivalent to a transition frequency between a first state and a second state. A second laser drive field having a frequency approximately equivalent to a transition frequency between the first state and a third state, and an infrared field having a frequency approximately equivalent to a transition frequency between the third state and a fourth state are received. The medium has a transition between the second state and the third state substantially forbidden to support optimal coherence on the transition between the second state and the third state. The infrared field is upconverted to generate a detectable field having a frequency approximately equivalent to a transition frequency between the second state and the fourth state.

Abstract: Infrared generation is disclosed. A first laser field having a first frequency associated with a first interband transition is generated. A second laser field having a second frequency associated with a second interband transition is generated. The generation of the first laser field occurs substantially simultaneously with the generation of the second laser field. A third laser field is generated from the first laser field and the second laser field. The third laser field has a third frequency associated with an intersubband transition. The third frequency is substantially equivalent to a difference between the second frequency and the first frequency.