Laser restructuring and photoluminescence of glass-clad GaSb/Si-core optical fibres

Abstract

Semiconductor-core optical fibres have potential applications in photonics and optoelectronics due to large nonlinear optical coefficients and an extended transparency window. Laser processing can impose large temperature gradients, an ability that has been used to improve the uniformity of unary fibre cores, and to inscribe compositional variations in alloy systems. Interest in an integrated light-emitting element suggests a move from Group IV to III-V materials, or a core that contains both. This paper describes the fabrication of GaSb/Si core fibres, and a subsequent CO 2 laser treatment that aggregates large regions of GaSb without suppressing room temperature photoluminescence. The ability to isolate a large III-V crystalline region within the Si core is an important step towards embedding semiconductor light sources within infrared light-transmitting silicon optical fibre.

CO2 laser annealed SiGe core optical fibers with radial Ge concentration gradients

“…The gradient forms due to thermomigration of Ge-rich droplets to the highest temperature, under the influence of the lateral temperature difference. During cooling of this partial-core laser-induced melting, Si-rich material precipitated first at the distal side of the liquid (partway through the core), and Ge-rich melt, with a lower melting point, solidified last, on the side where the laser was incident (red arrows) [24,30]. For the higher power annealing in Figs.…”

Broadband infrared and THz transmitting silicon core optical fiber

“…Silica clad optical fibers were drawn using the molten core method, [16] with a mixed core of HRFZ (ρ >5,000 ohm-cm) silicon and 10 at% Au. Eutectic systems allow laser-driven directional solidification of well-ordered crystalline samples for large core diameters, as seen by Song, et al [14]. Directional recrystallization and removal of the gold from the 210± 5 µm diameter, 0.035 mm 2 core was performed using a CO2 laser-based commercial tapering system (NYFORS SMARTSPLICER).…”

“…In addition to conventional scans, for each observed Bragg reflection, X-ray intensity was recorded as a function of the fiber's axial rotational position (φ scan). This allowed analysis of the number and orientation of crystal grains within the core [14]. The rectangular guides were cut from single crystal wafers and thus no XRD was performed.…”

“…A major challenge for fibers is the preference for a single or near-single crystal core to limit impurity inclusion and scattering losses but most studies on the recrystallization of silicon fibers have been done with smaller core material [11][12][13]. Recent advances in laser treatment have used an alloying element [14,15] to promote formation of single crystal large-core materials. Here, we report on broadband THz and infrared (IR) transmission of silicon-core samples fabricated using eutectic alloy annealing on molten-core drawn fibers, and compare them to rectangular guides made from high resistivity float-zone (HRFZ) silicon wafers.…”

Effect of Thermal Annealing on Mid-Infrared Transmission in Semiconductor Alloy-Core Glass-Cladded Fibers

“…Also it can form graded-index fibers that have not been reported in the mid-IR spectrum yet. Several studies were aimed to develop semiconductor alloycore fibers with various elements and compositions [13][14][15][16][17]. Recently, Si and Ge were used to form alloy-core fibers, however, the structural inhomogeneity of the alloy-core fibers causes high transmission losses, requiring post-fiber drawing processes [14,15].…”