CO₂ Laser‐Induced Directional Recrystallization to Produce Single Crystal Silicon‐Core Optical Fibers with Low Loss

Abstract

Reduced losses in silicon‐core fibers are obtained using CO2 laser directional recrystallization of the core. Single crystals with aspect ratios up to 1500:1 are reported, limited by the scan range of the equipment. This processing technique holds promise for bringing crystalline silicon‐core fibers to a central role in nonlinear optics and signal processing applications.

Crystalline GaSb-core optical fibers with room-temperature photoluminescence

“…The inset shows the deviation of the azimuthal angle of the diffraction spot on the detector as the fiber is translated, with variations less than ± 0.04 degrees from the average position. A single orientation was observed for the entire 2-3 mm annealed region of the fiber suggesting that larger single crystals could be produced [7,20] with a longer fiber. The annealed core material exhibited minimal strain and the clean, strong diffraction spot indicated that the crystal is of good quality.…”

“…The literature on Group IV semiconductor-core glass fibers is now significant [1][2][3][4][5], including processing improvements [6][7][8] and device demonstrations [9][10][11][12][13][14][15][16][17]. There are also reports on both SiGe alloy and II-VI core fibers [18][19][20][21][22][23], one including low temperature photoluminescence [21].…”

“…Based on results with Group IV alloy-core fibers [7], laser annealing is a promising approach for improving the structure of III-V compound cores. GaSb, which exhibits rapid oxidation, even at room temperature [27] but should be stabilized by encapsulation in glass, is of particular interest.…”

Interfacing Telecom Fibers and Silicon Core Fibers with Nano-Spikes for In-Fiber Silicon Devices

“…Investigations of the as-drawn SCFs have revealed that material absorption due to impurities, scattering from grain boundaries and density fluctuations in the core are the major contributions of optical losses [4]. However, several approaches have been successfully employed to improve the material quality of the as-drawn SCFs, including thermal annealing, laser recrystallization [5], and tapering [6]. So far, propagation losses as low as 1dB/cm have been reported.…”

Nonlinear optics in germanium mid-infrared fiber material: Detuning oscillations in femtosecond mid-infrared spectroscopy

“…13 Studies are focused on post fiber drawing/deposition processes to decrease the transmission losses. 14,15 An earlier study reported measurement of the Raman shift in Ge-core fibers arising from a vibrational normal mode in Ge. 16 Here we report the first nonlinear off-resonance optical material response in the Ge core of as-drawn fibers.…”