Gong Jingli, Wang Zhanyi, He Jian-Jun, Li Lu, Yang Rui Q, Gupta James A
Opt Express. 2023 Nov 6;31(23):38409-38418. doi: 10.1364/OE.504209.
Interband cascade lasers (ICLs) are efficient and compact mid-infrared (3-5 µm) light sources with many applications. By enhancing the coupling coefficient and using a type-I ICL wafer, single-mode ICLs were demonstrated based on V-coupled cavity with significantly extended tuning range and with a side mode suppression ratio (SMSR) exceeding 35 dB in continuous wave operation near 3 µm. A V-coupled cavity ICL exhibited a wavelength tuning up to 67 nm at a fixed temperature, and the total tuning range exceeds 210 nm when the heat sink temperature is adjusted from 80 to 180 K. The realization of single-mode in such a wide temperature range with a tuning range exceeding 210 nm verified the advantage of V-coupled cavity ICLs for effective detection of multiple gas species. This is very different from the conventional distributed feedback (DFB) laser where the single-mode operation is restricted to a narrow temperature range, in which the match between the gain peak and the DFB grating period determined wavelength is required. Another V-coupled cavity ICL is tuned over 120 nm from 2997.56 nm to 3117.50 nm with the heat-sink temperature varied from 210 K to 240 K, over 100 K higher than the previously reported maximum operating temperature for V-coupled cavity ICLs.
带间级联激光器（ICL）是高效且紧凑的中红外（3 - 5微米）光源，具有多种应用。通过提高耦合系数并使用I型ICL晶片，基于V形耦合腔展示了单模ICL，其调谐范围显著扩展，在3微米附近连续波工作时旁模抑制比（SMSR）超过35分贝。一个V形耦合腔ICL在固定温度下波长调谐高达67纳米，当散热器温度从80开尔文调整到180开尔文时，总调谐范围超过210纳米。在如此宽的温度范围内实现单模且调谐范围超过210纳米，验证了V形耦合腔ICL在有效检测多种气体种类方面的优势。这与传统分布反馈（DFB）激光器有很大不同，在传统DFB激光器中，单模工作被限制在很窄的温度范围内，其中需要增益峰值与DFB光栅周期确定的波长之间匹配。另一个V形耦合腔ICL在散热器温度从210开尔文变化到240开尔文时，从2997.56纳米调谐到3117.50纳米，超过120纳米，比之前报道的V形耦合腔ICL的最高工作温度高出100开尔文以上。
