Uusitalo Topi, Virtanen Heikki, Viheriälä Jukka, Dumitrescu Mihail
Opt Express. 2018 Jun 25;26(13):16303-16314. doi: 10.1364/OE.26.016303.
Dual longitudinal mode distributed feedback lasers have been fabricated using surface gratings with and without apodization. Analytic formulas and simulations that have been used to derive design guidelines are presented. The fabricated device characteristics are in good agreement with the simulations. The grating apodization enables a lower threshold current density, a higher output power and a broader range of difference frequency tunability by bias, which can be extended beyond the measured 15-55 GHz by changing the device structure. The apodization and the complex coupling of the surface gratings reduce the effects of the uncontrollable phase of facet reflections, enabling the use of higher facet reflectivities, which leads to narrower intrinsic short time-scale linewidths.
采用了带有和不带有切趾处理的表面光栅制备了双纵向模式分布反馈激光器。文中给出了用于推导设计准则的解析公式和模拟结果。所制备器件的特性与模拟结果吻合良好。光栅切趾处理能够实现更低的阈值电流密度、更高的输出功率以及通过偏置实现更宽范围的差频可调谐性，通过改变器件结构，可调谐范围可扩展到超过实测的15 - 55千兆赫。表面光栅的切趾处理和复杂耦合降低了刻面反射不可控相位的影响，从而能够使用更高的刻面反射率，这导致更窄的固有短时间尺度线宽。
