Ahmad H, Sharbirin A S, Samion M Z, Ismail M F
Appl Opt. 2017 Jul 20;56(21):5865-5870. doi: 10.1364/AO.56.005865.
A compact all-fiber multimode interferometer (MMI) designed to produce a switchable multi-wavelength thulium-doped fiber laser (TDFL) is proposed and demonstrated. The TDFL fiber ring cavity employs a 60-cm-long multimode fiber into the cavity to induce multimode interference and provide intensity-dependent loss in order to generate a multi-wavelength output. The suppression of mode competition and the overall stability of the TDFL are further improved by exploiting the filtering capability of a Sagnac loop. By increasing the pump power, a switchable wavelength output is allowed with a wavelength spacing of ∼1.8 nm. At 361 mW input pump power, nine laser lines are generated, with a maximum signal-to-noise ratio value of ∼36 dB and an output power of 3.3 mW. The multi-wavelength TDFL also exhibits great stability in one-hour operation with a wavelength drift of 0.2 nm. The proposed multi-wavelength TDFL has potential to be employed in future thulium-doped fiber amplifier-based telecommunication infrastructure and also may be applicable in areas such as sensing and spectroscopy, largely associated with its 2 μm wavelength output.
本文提出并演示了一种紧凑型全光纤多模干涉仪（MMI），该干涉仪旨在产生一种可切换的多波长掺铥光纤激光器（TDFL）。TDFL光纤环形腔采用一根60厘米长的多模光纤接入腔内，以引发多模干涉并提供强度相关损耗，从而产生多波长输出。通过利用萨格纳克环的滤波能力，进一步改善了TDFL的模式竞争抑制和整体稳定性。通过增加泵浦功率，可以实现波长间距约为1.8 nm的可切换波长输出。在361 mW的输入泵浦功率下，产生了九条激光谱线，最大信噪比约为36 dB，输出功率为3.3 mW。多波长TDFL在一小时的运行中也表现出极大的稳定性，波长漂移为0.2 nm。所提出的多波长TDFL有潜力应用于未来基于掺铥光纤放大器的电信基础设施，并且由于其2μm波长输出，也可能适用于传感和光谱学等领域。
