Tunable laser has become one of the most important components in coherent optical transmission system.Based on the existing integrated tunable laser module

a novel kind of miniaturized structure to realize high stability of devices is proposed in this paper

which is fabricated on silicon photonic-wire waveguides.The external cavity of lasers based on this structure is composed of an Semiconductor Optical Amplifier（SOA）

silicon micro-ring chip and two lenses.The paper analyzes the external wave locking and chip coupling.In our proposed scheme

the double lens and Spot Size Converter（SSC）are used for coupling between SOA and silicon chip

which can greatly reduce the cavity loss

improve the output power and coupling efficiency.The lasers have shown a wide tunning range covering the C bands and the output power can reach 14 dBm.