The recent development of semiconductor laser technologies for cost-effective telecom/datacom applications is reviewed in details in this paper. This includes the laser design, laser chip technology, laser packaging technology and other low cost lasers (chip + packaging). Some design and simulation examples in Archcom laser production are described first. A latest trend in the wafer scale testing/characterization/screening technology for low cost semiconductor laser mass production is discussed then. An advanced long wavelength high power single mode surface emitting laser with wafer scale characterization using our unique mask free focused ion beam (FIB) etching technology is also demonstrated. Detailed descriptions on our wide temperature range (-50 degrees C to +105 degrees C) G-PON distributed feedback (DFB) semiconductor lasers with high performance and low cost wafer design are included. Cost reduction innovations in laser package with our beam profile improved laser and optical feedback insensitive (OFBI) laser are also addressed.