Laser module

A laser module comprising:

• a quantum cascade laser element configured to generate a first terahertz wave having a difference frequency between a first frequency and a second frequency;
• and
• a light source configured to emit a second terahertz wave that is different from the first terahertz wave to the quantum cascade laser element, wherein
• the quantum cascade laser element includes:
• a substrate;
• a first clad layer provided on the substrate;
• an active layer that is provided on an opposite side of the first clad layer from the substrate, constitutes a resonator that oscillates a light of the first frequency and a light of the second frequency, and generates the first terahertz wave;
• a second clad layer provided on an opposite side of the active layer from the first clad layer;
• and
• a metal electrode provided on an opposite side of the second clad layer from the active layer,
• the second terahertz wave enters the active layer through the substrate, is reflected by the metal electrode, and is amplified or wavelength-converted, and
• a third terahertz wave, which is the second terahertz wave after being amplified or wavelength-converted in the active layer, is emitted to the outside through the substrate.