Lidar is a low-cost active detection tool for detecting a target's distance and 3D physical information. The vertical-cavity-surface-emitting laser (VCSEL)array is a light source that can improve the stability and compactness of lidar systems. However, the emission wavelength of a high-power VCSEL array is below 1000 nm, which can induce severe eye damage. Thus, the imaging range of the VCSEL lidar is limited. In this study, we report a high-power VCSEL array emitting at 1550 nm, an eye-safe wavelength.

The severe self-heating is the main problem of the 1550 nm VCSEL. To alleviate the thermal accumulation within the VCSEL emitters, we optimize the distribution of emitters within the VCSEL array. To characterize the thermal distribution accurately, the changes in thermal resistance with temperature and operation current are measured. A thermal model based on the VCSEL hexagonal cellular array units is built, and the temperature distributions within the units are analyzed. Thus, the unit spacing can be optimized.

The 1550-nm VCSEL array with an output power of more than 1 W under continuous-wave operation and more than 10 W under pulsed operation is reported (Figs. 6 and 8). Based on the characterization of the thermal resistance of single emitters under different operating currents, a thermal model of the VCSEL array is built, and the temperature distributions within different emitters of the array are simulated. As the distance between the edges of the VCSEL emitters exceeds 30 μm, the uniform temperature distribution within different emitters can be realized (Fig. 5). The output characteristics of the VCSEL array under continuous-wave and pulsed operations are characterized. The maximum output power of the VCSEL array can reach approximately 1.05 W in continuous-wave mode when the operating temperature is 15 ℃ (Fig. 6). The output power can reach 0.42 W even when the operating temperature of the VCSEL is increased to 65 ℃ (Fig. 6). The maximum output peak power of 10.5 W is obtained under pulsed operation with a pulse width of 5 μs and a repetition frequency of 1 kHz (Fig. 8). The profile of the far-field spot is still circularly symmetric, and the divergence angles are 26.69° and 26.98° in the orthogonal directions (Fig. 9).

A high-power VCSEL array emitting at 1550 nm is reported. The internal thermal resistance is obtained by characterizing the thermal characteristics of the single emitters. The temperature distributions within the VCSEL array are simulated, and the distance between the emitters in the VCSEL array is optimized. The maximum continuous-wave output power of 1.08 W and pulsed output power of 10.5 W are achieved. The 1550-nm VCSELs have excellent eye safety performance and great advantages in terms of cost, volume, and integration in future technologies. We believe that the 1550-nm VCSEL array will have broad application prospects in 3D sensing, such as under-screen recognition, laser radar, and other fields in the future.