ABSTRACT
Integrated twin-guide (ITG) lasers were proposed and developed as one of the integrated lasers in 1974. Integrated lasers are kind of lasers, which enable a monolithic connection from the laser section to a low-loss output waveguide to be realized. The strongly coupled waveguide system like ITG can be analyzed on a base set of two guided modes which are given by an exact solution of the electromagnetic wave equation of the system. The chapter analyzes the oscillation condition of ITG lasers. The oscillation condition of the ITG lasers be analyzed by use of the matrix method. Various types of ITG lasers are devised by combination of the basic ITG lasers and the distributed Bragg reflectors. The double-resonator type of ITG lasers, Type 1, is the basic ITG laser structure, which has four mirrors at both ends of the active and output waveguides, and axial-mode selectivity is expected due to the double-resonance effect.
