Zero-energy topological states, which are protected by chiral symmetry against certain perturbations topologically, localize at interfaces between trivial and non-trivial phases in the Su–Schrieffer–Heeger (SSH) chain model. Here, we propose and demonstrate a method to manipulate chiral symmetry itself to improve the localized interfaces and enlarge the mode volume of topological states in the SSH model, thus optimizing the lasing performance of localized interfaces. As multiple defects corresponding to off-diagonal perturbations in an eigenmatrix are introduced, the topological state expands and extends to extra defects at the topological interface without breaking chiral symmetry. We apply the proposed method in electrical pumping semiconductor laser arrays to verify our theoretical prediction and optimize the output characteristics of the devices. The measured results of the proposed multi-defect SSH laser array show that the output power has been increased by 27%, and the series resistance and far-field divergence have been reduced by half compared to the traditional SSH laser array, establishing a high-performance light source for integrated silicon photonics, infrared light detection and ranging, and so on. Our work demonstrates that the proposed method is capable of improving topological localized interfaces and redistributing zero-energy topological states. Furthermore, our method can be applied to other platforms and inspire optimizations of more devices in broader areas.
2023, 11(9): 1517
A high peak power density and low mechanical stress photonic-band-crystal (PBC) diode laser array based on non-soldered packaging technology is demonstrated. The array consists of the PBC diode laser bars with small fast axis divergence angles. Meanwhile, we design the non-soldered array structure that realizes mechanical stacking of 10 bars in the vertical direction. In the experiment, the peak power density of the PBC array is about 1.75 times that of the conventional array when the same total power is obtained. The peak power of the non-soldered array is 292.2 W, and the “smile” effect is improved by adjusting the mechanical fixing force of the array.photonic-band-crystal non-soldered packaging low mechanical stress
Chinese Optics Letters
2022, 20(7): 071403