Patent ID: 7693198

Claim:
A laser device comprising a waveguide with a resonant structure for resonating an electromagnetic wave, the waveguide including: a gain medium for generating the electromagnetic wave; a first cladding, which is in electrical contact with the gain medium, and which has a negative real part of a dielectric constant for the electromagnetic wave; a second cladding, which is in electrical contact with the gain medium, and which is provided on a side opposite to a side of the first cladding, such that the gain medium is sandwiched between the first and second claddings, and which has a negative real part of a dielectric constant for the electromagnetic wave; and a lateral structure, which is arranged so as to be in contact with at least one side surface of the gain medium, such that the lateral structure is sandwiched between the first and second claddings, and which has a positive real part of a dielectric constant for the electromagnetic wave, wherein a wavenumber of a surface plasmon held by the lateral structure is smaller than a wavenumber of a surface plasmon held by the gain medium.