| 摘要 |
The present invention is provided with a semiconductor substrate (10) and first and second active layers (15, 25) provided in series on the substrate, so as to constitute a quantum-cascade laser (1A). A unitary laminated article (16) of the first active layer (15) has within a sub-band level structure a light-emission upper level and a light-emission lower level, and is configured to be able to generate light having a first frequency (ω1). A unitary laminated article (26) of the second active layer (25) has within a sub-band level structure a first light-emission upper level, a second light-emission upper level, and a plurality of light-emission lower levels, and is configured to be able to generate light having a second frequency (ω2). Light having the difference frequency (ω) is generated by difference frequency generation using the light having the first frequency (ω1) and the light having the second frequency (ω2). This yields a quantum cascade laser capable of suitably generating light having a long wavelength, such as terahertz light. |
