Novel Growth Techniques for the Fabrication of Photonic Integrated Circuits

The fabrication of Photonic Integrated Circuits (PIC) requires the development of advanced growth and processing techniques. One of the major problems in the fabrication of PICs is the monolithic integration of passive and active waveguiding structures with a different bandgap. This is schematically shown in figure 1 where a laser, waveguide and detector are integrated on the same substrate. The following relationship between the different bandgaps is required : Eg (detector) < Eg (laser) < Eg (waveguide). One of the most advanced PICs is certainly a coherent receiver chip where a local DFB laser oscillator is integrated with a Y-junction, 3-dB splitter and balanced photodetector pair [1,2,3]. Current integration schemes are mostly based on the use of different epitaxial growth steps to obtain the different bandgap materials on the same substrate. In order to improve yield and performance it is required to reduce the number of growth steps by using special growth techniques. In this paper we will briefly describe some of the recent developments in advanced growth techniques. A more detailed description will be given of our recent work based on selective growth and shadow masked growth using Metal Organic Vapour Phase Epitaxy (MOVPE).