Optical gain-bandwidth product of vertical-cavity amplifiers

Summary form only given. Vertical-cavity semiconductor optical amplifiers (VCSOAs) have recently attracted increasing interest. They are potentially low-cost alternatives to in-plane SOAs and they have the inherent advantage of polarization insensitivity, high fiber coupling efficiency, and low noise figure. Two-dimensional arrays of VCSOAs are attractive for parallel applications. We have recently demonstrated the first VCSOA that operates at 1.3 /spl mu/m signal wavelength. In our undoped and optically pumped device, two AlAs/GaAs distributed Bragg reflectors (DBRs) are wafer bonded to an InP based active region. The active region contains three stacks of 7 compressively strained InAsP quantum wells that are placed at the three central peaks of the standing optical wave. The effective cavity length is 2.2 /spl mu/m including light penetration into the mirrors. The quantum wells are the only layers to allow for band-to-band absorption of the 980 nm pump laser beam. Up to 13 dB fiber-to-fiber gain, -3.5 dBm saturation output power, and 0.6 nm optical bandwidth (100 GHz) are measured in reflection mode. Low optical bandwidths are desirable for filter applications whereas larger bandwidths are needed for wavelength division multiplexing. Due to the trade-off between gain and bandwidth, we use here the gain-bandwidth product as figure of merit.