Thermal design of circular VCSEL arrays for optical output performance improvement

With the aid of the thermo-electro-optical model of two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays, the layout of circular VCSEL array is optimized to improve the optical output performance. Taking a circular VCSEL array with 19 cells (including 2 circles) for example, the impact of circle radius (r) and deviated angle from the symmetry center of the array (θ) on the non-uniformity of junction temperature profile are studied in detail. It is shown that increasing the inner circle radius r could decrease the peak junction temperature difference effectively. At the same time, the outer circle diameter is unchanged to keep the total area of the array remains the same. Moreover, the deviated angle θ could be designed carefully to further improve the non-uniformity of junction temperature profile. As a result, a novel circular VCSEL array with inner circle radius r of 42μm and deviated angle θ of 23° is proposed, where the non-uniformity of junction temperature profile and bias current distribution is improved by 43.66% and 44.07%, respectively, and hence enhance the optical output power, when compared with that of the conventional circular VCSEL array.