Due to their high level of integration, vertical-cavity surface-emitting lasers (VCSELs) are promising candidates for applications in quantum communication and sub-Doppler atomic microsystems. However, there is an urgent need to develop narrow line width, high-quality VCSELs that provide stable and reliable emission to meet commercial demands. Here, we demonstrate a novel coupled-cavity VCSEL integrated with a cholesteric liquid crystal (CLC) film to develop high-performance ultranarrow line width VCSELs. The CLC film can be flexibly integrated onto the surface of the VCSEL and applies weak light feedback which enhances the coherent superposition and compresses the line width of the VCSEL. It has been shown that when the length of the coupled cavity is less than 150 μm, it can suppress the higher-order modes and significantly reduce the threshold current of VCSEL. Furthermore, the CLC-VCSEL exhibits circular polarization output and an impressive line width of 2.46 MHz, which is the narrowest micron-scale integration VCSEL as reported, comparable to the line width of distributed Bragg reflection and distributed feedback semiconductor lasers. Compared with recently reported high-performance VCSELs and semiconductor lasers, the CLC-VCSELs achieve a lower threshold current and an enhanced beam quality. This micrometer-scale coupled cavity VCSEL will provide more possibilities for the development of next-generation VCSELs and integrated packages for CLC modulation. Moreover, the CLC optical feedback technique is not exclusive to VCSEL and can also be applied to other optoelectronic devices, such as low-power edge-emitting lasers, quantum dot lasers, and so forth.

中文翻译：

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2.46 MHz 超窄线宽垂直腔面发射激光器，具有胆固醇液晶耦合腔


由于其高度集成度，垂直腔面发射激光器 （VCSEL） 是量子通信和亚多普勒原子微系统应用的有前途的候选者。然而，迫切需要开发窄线宽、高质量的 VCSEL，以提供稳定可靠的发射以满足商业需求。在这里，我们展示了一种与胆固醇液晶 （CLC） 薄膜集成的新型耦合腔 VCSEL，以开发高性能超窄线宽 VCSEL。CLC 薄膜可以灵活地集成到 VCSEL 的表面上，并施加微弱的光反馈，从而增强相干叠加并压缩 VCSEL 的线宽。研究表明，当耦合腔的长度小于 150 μm 时，它可以抑制高阶模式并显着降低 VCSEL 的阈值电流。此外，CLC-VCSEL 具有圆极化输出和令人印象深刻的 2.46 MHz 线宽，这是据报道的最窄微米级集成 VCSEL，与分布式布拉格反射和分布式反馈半导体激光器的线宽相当。与最近报道的高性能 VCSEL 和半导体激光器相比，CLC-VCSEL 实现了更低的阈值电流和更高的光束质量。这种微米级耦合腔 VCSEL 将为开发下一代 VCSEL 和 CLC 调制集成封装提供更多可能性。此外，CLC 光反馈技术并非 VCSEL 所独有，也可以应用于其他光电器件，例如低功率边缘发射激光器、量子点激光器等。