Fig. 1. Simulation results of optical confinement factor and internal loss varying with number of quantum wells

Fig. 2. 1.3 μm DFB laser. (a) Schematic diagram of three-dimensional structure of laser; (b) schematic diagram of epitaxial structure of laser; (c) scanning electron microscope diagram of ridge waveguide in laser; (d) top view of actual manufactured core

Fig. 3. P-I-V test results of laser

Fig. 4. Characteristic temperature test of laser. (a) P-I test results at 20-80 ℃; (b) relation curve between threshold current and temperature, and characteristic temperature fitting

Fig. 5. Spectral diagram of device at different currents under 25 ℃

Fig. 6. Laser spectrum varying with temperature at pulse width of 40 μs and pulse period of 1000 μs. (a) Lasing spectra at different chip temperatures; (b) relationship between lasing wavelength of device and chip temperature, and result of linear fitting

Fig. 7. Test result of laser linewidth

Fig. 8. Frequency response test curves of laser under different currents

Fig. 9. Eye graph test results of different transmission rates at 25 ℃. (a) 25 Gb/s; (b) 30 Gb/s; (c) 35 Gb/s; (d) 40 Gb/s