Superluminescent diodes(SLDs) can usually be taken as a light source for fiber optic-gyroscopes

wavelength-division multiplexing(WDM) systems and optical coherence tomography(OCT).Because of their high working current density

the output power

lifetime and the spectrum stability may be strongly influenced by the temperature in the active region increasing with injection current.Using MQWs(multiple quantum wells) as active layers can decrease the working current density

reduce Joule heating effect

and increase the differential gain of the device.In this contribution

we calculated the thermal resistance and temperature distribution of InGaAsP/InP MQW SLDs which are influenced by their lateral chip size and composition with two-dimension thermal flow model.The results reveal that when the injection power reaches 1 W

the temperature of active region will be almost 50 K.The width and length of chip also have strong influence on the thermal resistance which can reach two orders of magnitude.The thermal resistance will change from 290 K/Wto 68 K/Wwhen width of chip was increased from 500 μm to 2500 μm.For the length of chip

there is similar result. But there is small effect on thermal resistance for active width.All the results will be useful for structure and composition design of SLD.