W2.5.pdf Workshop on Specialty Optical Fibers and their Applications © OSA 2013 Development of highly nonlinear single mode chalcogenide microstructured optical fiber for Brillouin fiber laser applications Brilland Laurent 1 , Toupin Perrine 2 , Troles Johann 2 , Hey Tow Kenny 3 , Besnard Pascal 3 , Méchin David 1 1 Perfos, R&D Platform of Photonics Bretagne, Lannion, France 2 Glass and Ceramic Team, UMR CNRS 6226, Rennes Chemical Sciences, France 3 CNRS FOTON laboratory, ENSSAT Lannion, France lbrilland@perfos.com Abstract: A 4μm-core GeAsSe microstructured optical fiber has been developed for nonlinear applications. A 3-meter long fiber has been used ina Brillouin fiber laser cavity with a low laser threshold power. OCIS codes: (000.0000) General; (000.0000) General [8-pt. type. For codes, see www.opticsinfobase.org/submit/ocis.] 1. Introduction Chalcogenide glasses are known for their large transparency window in the mid-infrared and their high nonlinear optical properties. For instance, the nonlinear refractive index, n 2 of a well-known AsSe glass can be more than 500 times larger than the one of silica [1]. The nonlinear effects are significantly enhanced in a small core (<5 μm) chalcogenide optical fiber and can be used, for optical processing such as regeneration in telecommunication, supercontinuum generation or in Brillouin laser. For these applications, a single mode fiber is required. However, it is still a challenge to obtain such small core chalcogenide fiber with low optical losses. The Microstructured Optical Fibers (MOF) are good candidates for nonlinear applications. They exhibit several interesting properties such as singlemode guiding with a small effective area. Recently, a casting method has been developed to produce chalcogenide microstructured preform [2]. Suspended core AsSe MOF have been elaborated previously, however, they were still exhibiting a multimode behavior [3] despite their very small core area (5.1 μm 2 ). To realize a small core singlemode chalcogenide MOF, a several-step process is required. First, a high purity glass preform with 3 rings of holes is elaborated using the casting method. The preform is then reduced to a cane of a diameter of a few mm. The cane is placed in a jacket tube and drawn into the desired MOF. In our previous studies, we proved that the multiple step process leads to the crystallization of the AsSe MOF. In contrary, we demonstrated that the composition GeAsSe supports multiple drawing steps. A 4 μm diameter singlemode Ge 10 As 22 Se 68 with optical losses lower than 1dB/m at 1.55 μm has been successfully fabricated [4]. A 3- meter long MOF has been used as a gain medium to obtain a Brillouin laser with a threshold pump power of only 6 mW and 30 mW respectively for the first and second Stoke component. 2. GeAsSe Microstructured Fiber Fabrication A highly purified GeAsSe MOF has been previously synthetized. During the fiber drawing step, the pressure applied in the holes is carefully controlled. Figure 1 presents the cross section of the GeAsSe fiber with an external diameter of 125 μm, core size of nearly 4μm and d/pas=0.4. The optical losses are 0.65 dB/m at 1.55 μm. Fig 1: SEM picture of GeAsSe small core singlemode fiber. Core diameter=4μm. Loss≈0.65 dB/m@ 1.55μm 3. Chalcogenide MOF Brillouin Fiber Laser