Fig. 1. The structure of LM-LC-DFB lasers and the research on the optical field distribution of the modes in a wide-ridge waveguide semiconductor laser. (a) Schematic diagram of the laser structure; (b) Optical field distribution of the modes in a wide-ridge waveguide semiconductor laser

Fig. 2. Schematic diagram of the mechanism of the lateral loss structure's effect on the optical field distribution in a laser. (a) TE₀; (b) TE₁; (c) TE₄ (The sum of the ridge width and the lateral depth of the loss structure is 50 μm)

Fig. 3. The relationship between the width of the loss structure region and the loss of each order transverse mode

Fig. 4. The relationship between the grating confinement factor, etching depth, and coupling coefficient. (a) The relationship between the grating confinement factor and the etching depth; (b) The relationship between the grating coupling coefficient and the etching depth

Fig. 5. The relationship between the coupling coefficient and the duty cycle

Fig. 6. Far-field optical spot of the device. (a) Far-field optical spot of the WR-LD; (b) Far-field optical spot of the LM-LC-DFB

Fig. 7. Device characteristic curve diagram. (a) LM-LC-DFB and WR-LD power curves; (b) Electro-optical conversion efficiency of LM-LC-DFB and WR-LD

Fig. 8. Device spectral curve diagram. (a) Spectral characteristics of the LM-LC-DFB device; (b) Spectral characteristics of the WR-LD device