Janjua Bilal, Lon Iu Meng, Charles Paul, Chen Eric, Helmy Amr S
Opt Lett. 2020 May 1;45(9):2490-2493. doi: 10.1364/OL.387448.
We have designed and fabricated a monolithic semiconductor ring laser based on a Bragg waveguide structure. Through careful control of the waveguiding, we have overcome the inherent "leaky" nature of this waveguide mode and demonstrated a ring laser lasing in the Bragg mode. Best behavior was obtained from lasers with a diameter of 400 µm, where they exhibited output power ${ \gt }{1};{\rm mW}$>1mW, in continuous wave (CW) operation. A tangent waveguide provided access to the ring cavity using two ports through evanescent coupling. To meet the stringent waveguiding requirements imposed by the Bragg structure, a two-step etching process, consisting of a shallow-etched coupler and a deep-etched bend section of the ring, was developed in order to reduce the bend and scattering losses. The laser showed a threshold current density of ${\sim}{2.2};{{\rm kA/cm}^2}$∼2.2kA/cm in CW operation with single longitudinal mode operation with a signal-to-noise ratio of 30 dBm obtained at 1.5 ${I_{\rm th}}$I. Broadband phase-matching of $\chi ^{(2)}$χ nonlinearity is observed, offering self-pumped parametric C-band conversion ${ \gt }{40};{\rm nm}$>40nm with efficiency of ${142}% ;{{\rm W}^{ - 1}};{{\rm cm}^{ - 2}}$142%Wcm.
我们设计并制造了一种基于布拉格波导结构的单片半导体环形激光器。通过对波导的精确控制，我们克服了这种波导模式固有的“泄漏”特性，并展示了在布拉格模式下激射的环形激光器。直径为400 µm的激光器表现最佳，在连续波（CW）运行中，其输出功率大于1 mW。一个切线波导通过倏逝耦合利用两个端口接入环形腔。为满足布拉格结构对波导的严格要求，开发了一种两步蚀刻工艺，该工艺包括一个浅蚀刻耦合器和环形的深蚀刻弯曲部分，以减少弯曲和散射损耗。该激光器在连续波运行中显示出阈值电流密度约为2.2 kA/cm²，在单纵模运行时，在1.5倍阈值电流I处获得了30 dBm的信噪比。观察到χ(2)非线性的宽带相位匹配，实现了大于40 nm的自泵浦参量C波段转换，转换效率为142% W⁻¹ cm⁻²。
