Study On 970nm Strained Quantum Well Superluminescent Light Emitting Diode

Superluminescent light-emitting diodes(SLDs)are a new type of semiconductor optoelectronic devices that combine highly directional laser diode(LD)beams with light-emitting diode(LED)incoherent broadband light-emitting properties.The ideal superradiant light is an incoherent light source with different phases,also called a short coherent light source.The improvement of the directivity of the SLD beam makes it more efficient in coupling with the lens system or optical fiber,which can be used in the fiber optic gyroscope of the navigation system for precise rotation measurement,and is also widely used in biomedicine and optical coherence tomography(OCT)for industrial imaging and other fields.In order to fill the light source application of OCT optical coherence tomography in the 970 nm band,this paper mainly studies the high-power,wide-spectrum curved ridge superluminescent light-emitting diodes.(1)Based on strain compensation theory and finite-depth potential well function eigen-differential equation,the relationship between lasing wavelength and well width was simulated for the epitaxial structure of triple quantum well In Ga As/Ga As material system.Simulations show that the lasing wavelength increases with the increase of the well width when the In composition is the same.(2)An analytical model was established based on the beam propagation method(BPM)and the finite difference time domain(FDTD)method to simulate and analyze the effects of different structural parameters(etching depth,curvature radius,ridge width)on the waveguide loss of the curved ridge superluminescent diode.The effect of different ridge structures on the modal reflectivity(tilt angle,emission wavelength)of the inclined end faces.The results show that the etching depth and curvature radius of the curved ridge waveguide are important factors affecting the waveguide loss.The shallow etching depth makes the waveguide’s confinement effect on the optical field weaker,and the too small curvature radius will cause serious mode transmission leakage and greatly increase the loss.The larger the ridge width,the smaller the waveguide loss,and the smaller the influence on the waveguide loss.The inclination angle of the inclined ridge waveguide structure is the main factor for suppressing the mode reflectivity.With the continuous increase of the inclination angle and the ridge width,the mode reflectivity gradually decreases,and forms a singularity at a specific angle and reaches a minimum value.When the emitted wave is a composite wave,the singularity disappears and fills the minimum of the mode reflectivity.As the etch depth increases,the mode reflectivity increases,and the angle at which the singularity occurs shifts to a small tilt angle.(3)Through the optimization of the preparation process: photolithography,development,ICP dry etching,ohmic contact,and thinning polishing and other process parameters,and in order to improve the optical cavity surface damage threshold and life of the device,a cavity film was evaporated on the device.A 970 nm superluminescent light-emitting diode with a ridge width of 4μm and a ridge height of 1.4μm was fabricated.The device was tested,and the test results showed that the output power of the device prepared by the dry etching process was 74 m W under the injection current of 1000 m A at room temperature,the central emission wavelength was 970 nm,and the full width at half maximum of the spectrum reached more than 24 nm.