The middle infrared (mid-IR) wavelength region between 2-5um is of great interest due to a wide variety of applications such as spectroscopy, or free-space communications and demand for high quality mid-IR lasers has significantly increased over the last decades. In conjunction, the ability to rapidly sweep wavelength has fueled many major developments such as real-time fiber sensor examination and chemical sensing.
While significant research efforts are being funneled in the design of mid-IR sources, the need for compact and robust mid-IR wavelength swept source is ever present. The present proposal is aimed at fulfilling this need by designing a novel fiber based mid-IR wavelength swept source. A typical swept source is divided into two distinct components (gain medium and tunable filter) which hinders the tunablity and speed of the device. We thus propose to combine the two in a single element, eliminating these limitations. Combining gain and filtering is a concept supported by narrowband fiber optic parametric amplifier which has the definitive advantage that its gain spectrum is only limited by the transparency of the waveguide used. We therefore propose the use of heavy metal fluoride glass ZBLAN, with transparency up to 5um, inside a parametric oscillator pumped by a near-IR source. This constitutes a novel and promising approach which will combine mature near-IR devices with mid-IR materials in order to transfer near-IR performances to the region of interest. Mid-IR wavelength sweep will be directly controlled by the wavelength-swept near-IR pump for ease of use. A speed up inherent to four wave mixing will enable high sweeping speeds while maintaining high quality light generation. The proposal will thus explore phase matching in ZBLAN based narrow band parametric amplifiers while simulation and experimental characterization will be performed. The performance of the designed mid-IR source and potential for spectroscopic application will be assessed.
Fields of science
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