Selective movpe growth and its application to semiconductor photonic integrated circuits

Considerable research and development have been done on semiconductor photonic integrated circuits in which various components such as a laser diode and other photonic devices were integrated. In this paper, a 1.55-μm band wavelength division multiplexing (WDM) integrated light source for optical communication is developed and the results of the evaluation are described. Four-channel laser sources were fabricated by integrating tunable semiconductor lasers and semiconductor optical modulators plus multiplexers, and the possibility of using a 2.5-Gbit/s high-density WDM optical transmission system is discussed. After analyzing the problems encountered in the fabrication of these photonic integrated components, the development of a bandgap energy-controlling technique of quantum well structure using the selective metal oxide vapor-phase epitaxial (MOVPE) growth, which is a better fabrication technique, is described. By using this technique, the difficult process of combining the waveguide with a different bandgap energy can be accomplished only by a one-step crystal growing. This simplifies the components fabrication, and a high-coupling efficiency of the waveguide between the integrated elements can be obtained. As an application example, the integrated light source was fabricated by integrating a tunable laser, distributed feedback (DFB) laser, and semiconductor optical modulator. Then the tunable characteristic and the extinction characteristic were verified. This simplifies the fabrication method of the previously difficult method of semiconductor photonic integrated circuits and clarifies the possibility of developing a high-density integrated element.