Partial Regrowth of Optical-Gain Section for Improved Wafer Process Flexibility of InP Photonic Integrated Circuits

We developed a semiconductor regrowth scheme for InP photonic integrated circuits (PICs) with optical-gain sections. Unlike conventional semiconductor regrowth schemes, a limited area corresponding to a 200-μm waveguide of an original epitaxial wafer is replaced with an optical-gain material, which improves the flexibility of a PIC process design. In this paper, we describe the partial regrowth (PRG) procedure using a window regrowth mask that defines the regrowth area. A minimum window in terms of semiconductor quality assurance is determined by observing the micro-photoluminescence intensities of the replaced regions. We also show basic performances of optical semiconductor amplifiers (SOAs) obtained by the PRG including amplification of in-phase/quadrature modulation optical signals. Furthermore, practical InP PIC applications of the PRG are also depicted: an SOA-integrated Mach-Zehnder modulator and an electrooptically tunable laser with an arrayed gain.