Large modal volume semiconductor laser system with spatial mode filter

A semiconductor optical amplification system that uses a single-mode fiber angle-coupled to a semiconductor wave-guide medium with optical gain. This design is particularly simple and relevant to optical fiber systems, but it may be generalized to include other implementations as well, in which other spatial mode filters are employed. A chip design is employed in which lowest order mode has a size greater than about 5 micrometers (mum). Thus, much smaller facet angles can be employed while still avoiding self-oscillation. More specifically, according to some aspects of the invention, facet angles of less than 4 to 5 degrees are utilized.