power the sgbdr laser elements may be controlled separately from the amplifier to tune the laser frequency and otherwise control the input to the optical amplifier by this arrangement of elements power amplification and tuning functions are substantially uncoupled in the embodiment of fig1 a optical amplifier 190 has an active section and a passive section the active section amplifier gain section 110 is substantially straight the passive section of waveguide 105 is curved and intersects output facet 195 at an oblique angle both waveguide curvature and the oblique intersection with the output facet act to prevent reflections at the output facet from coupling back into the optical amplifier 190 and laser 180 fig1 b shows a longitudinal cross section of a laser assembly 100 of fig1 a in fig1 b laser assembly 100 waveguide 105 amplifier gain section 110 front resonator mirror 120 laser gain section 130 laser phase control section 140 back mirror 150 and electrical contact 160 epitaxial structure 170 laser 180 optical amplifier 190 output facet 195 p type semiconductor layer 125 n type semiconductor layer 115 mirror sampling period 135 offset quantum wells 145 and stop etch layer 155 are shown in fig1 b waveguide 105 is formed between p type and n type semiconductor layers 125 and 115 respectively mirrors 120 and 150 are formed by sample gratings etched in waveguide 105 with sampling period.