Active multi-mode interferometer (MMI) laser diodes were realized in InGaAsP/InP for high-power applications. They achieved increases in output powers of 90 mW, which correspond to 30% increases, as compared to the powers of regular single-lobe laser diodes fabricated simultaneously with the active MMI-LDs. The resulting maximum powers of the active MMI-LDs were 380 mW at a wavelength of 1.45 μm. The implemented active MMI-LDs showed stable regular single-transverse-mode outputs up to the maximum power.

Inductively coupled plasma (ICP) etching technique was applied to fabricate high power InP/InGaAsP buried-hetero structure laser diodes. Low internal losses of 6 cm/sup -1/ and internal quantum efficiencies of 83%, which resulted in high power of 290 mW output, were obtained under extremely fast mesa-etching with 1.2 /spl mu/m/min.

A new type of semiconductor optical amplifier (SOA), consisting of a singlemode waveguide with a 1/spl times/1 multimode-interferometer (MMI) section, is proposed and experimental results presented. Maintaining single lobed outputs these new MMI amplifiers show improvements of 2 dB in gain and 5 dB in saturation output compared to regular single-stripe SOAs.

An active multimode interferometer (MMI) laser diode (LD) concept is presented, which has been verified via a 1.48 mu m high power application. The active MMI-LDs, having a larger pumping area compared to that of regular single-stripe LDs with the same length showed no significant degradation in slope efficiency and up to 50mW power improvement resulting in 170 mW saturated output power.

A novel laser diode, in which the pumping area is increased by a multi-mode interference (MMI) coupler, is proposed to maintain single-lobe outputs up to high powers. Utilising active 1x1 MMI couplers between singlemode waveguides, up to 90% higher single-lobe and fibre-coupled output powers were obtained at 1.3 mu m.