894 nm高温工作氧化限制型基横模VCSEL研究

针对芯片原子钟（铯）用激光光源系统对垂直腔面发射激光器（VCSEL）模式及工作温度的需求，研制出可以高温工作的氧化限制型基横模 894.6 nm VCSEL。通过缩小VCSEL氧化孔直径至3 μm，限制VCSEL高阶横模激射，保证器件基横模低阈值电流工作。通过常温下腔模与材料增益失谐12 nm 的结构设计，使器件能够在50~65 ℃ 高温时，激射波长对准原子能级且工作模式稳定。实验所制备的VCSEL在工作温度为55 ℃、注入电流1.8 mA 时，激射波长达到 894.6 nm，边模抑制比（SMSR）大于35 dB，基横模功率为0.75 mW，具有11.4°的远场发射角。当温度为65 ℃时，器件SMSR大于25 dB，基横模功率大于0.1 mW。该高温基横模工作的VCSEL在芯片原子钟中具有重要的应用前景。

Study of high-temperature operating oxide-confined 894 nm VCSEL with fundamental transverse mode emission

Aiming at the requirements of the mode and operating temperature of vertical-cavity surface-emitting laser (VCSEL) used as the laser source system of the atomic clock (Cesium) chip, the 894.6 nm oxide-confined fundamental transverse mode VCSEL that could operate at high temperature was reported. By reducing the diameter of the oxide aperture of the VCSEL to 3 μm, the higher order transverse modes could be suppressed, which guaranteed the fundamental transverse mode and low threshold current of the VCSEL. Through the structural design that the cavity mode and the material gain was detuned by 12 nm at room temperature, the emission wavelength of the device could match with the atomic energy level and the operating mode was stable at a high temperature of 50-65 ℃. The obtained VCSEL shows a center wavelength of 894.6 nm, a side mode suppression ratio (SMSR) larger than 35 dB, a fundamental transverse mode power of 0.75 mW and a far-field divergence angle of 11.4° when the operating temperature is 55 ℃ and the injection current is 1.8 mA. At the temperature of 65 ℃, the SMSR is larger than 25 dB and transverse mode power is larger than 0.1 mW. The development of the high temperature fundamental transverse mode VCSEL has great potential in chip atomic clocks.