1.3 /spl mu/m laser diodes with large spot size and low loss fibre-chip coupling fabricated by standard buried heterostructure laser processes

We present a simple expanded output mode semiconductor diode laser without spot size transformer. The laser spot size expansion is achieved by decreasing the effective refractive index step between the core and cladding. The major advantage of this approach is that the laser can be fabricated with conventional buried heterostructure technology with no inherent resolution limits and no need for additional sophisticated etching or epitaxial techniques, avoiding any significant cost increase of the laser chip. Moreover, this approach is suitable for mass production. The fabricated LDs show good lasing characteristics and low loss coupling of less than -4.3 dB into a cleaved single mode fibre with good misalignment tolerance.