New Laser Structure for Polarization Insensitive Semiconductor Amplifier with Low Current Consumption,

Due to their low current consumption and their intrinsic simplicity polarization insensitive semiconductor travelling wave amplifiers TWAs are very attractive components for long haul non regenerated fiber transmissions systems. It appears up to now that only buried stripe with width less than one micron has enabled to obtain high gain and polarization insensitivity for low bias current I - 4. However realization of such narrow stripe leads to poor reproducibility in case of conventional laser structure. We have investigated a new structure, called modified double channel planar buried heterostructure MDCPBH, which allows to process very narrow stripe with much better reproducibility than previously obtained. Recently high fiber to fiber gain and low polarization sensitivity have been published 4 using buried window structure but for cur-rent higher than 150 mA and it was necessary to use bulk optics for packaging. MDCPBH structure with small area square active stripe section and TiO2SiO2 two layers coating has enabled to achieve simultaneously for TE and TM modes reflectivities as low as 10-4 and reproducible fiber to fiber gains higher than 14 dB using lensed fiber for bias current lower than 100 mA.