Carrier-confined vertical-cavity semiconductor optical amplifiers for higher gain and efficiency

Vertical-cavity semiconductor optical amplifiers (VCSOAs) are interesting devices because of their small form factor, potential low manufacturing cost, high coupling efficiency to optical fiber, and polarization-independent gain. In this paper, we present an overview of the properties of VCSOAs, as well as emerging applications for this new class of devices. We present general design rules and analyze how the mirror reflectivity affects the properties of the VCSOA. Experimental results of carrier-confined, optically pumped VCSOAs operating at 1.3-mum wavelength are presented. The devices were fabricated by wafer bonding high-quality AlGaAs distributed Bragg reflectors (DBRs) to an InGaAsP/InP active region. A carrier-confining structure was formed on the active region before the top mirror was bonded to the sample. These VCSOAs show the highest fiber-to-fiber gain (17 dB) and the lowest noise figure (6.1 dB) of any long-wavelength VCSOAs to date. VCSOAs should find applications as low-cost, single-channel amplifiers, amplifying filters, amplifying switches or modulators, as well as in two-dimensional array applications such as optical interconnects. We demonstrate the use of VCSOAs for optical preamplification at 10 Gb/s. Using an 11-dB gain VCSOA, the sensitivity of a regular p-i-n detector was increased by 7 dB resulting in a receiver sensitivity of -26.2 dBm.