Embedded optical waveguides fabricated in SF10 glass by low-repetition-rate ultrafast laser

Abstract

Symmetric embedded waveguides were fabricated in heavy metal oxide SF10 glass using slit-shaped infrared femtosecond laser writing in the low-repetition frequency regime. The impact of the writing parameters on the waveguide formation in the transverse writing scheme was systemically studied. Results indicate that efficient waveguides can be inscribed in a wide parameter space ranging from 500 fs to 1.5 ps pulse duration, 0.7-4.2 μJ pulse energy, and 5 μm∕s to 640 μm∕s scan speed and pointing out the robustness of the photoinscription process. The refractive index profile reconstructed from the measured near field pattern goes up to 10 −3 . In addition, propagation losses of the waveguides are tolerable, with the lowest propagation loss estimated at 0.7 dB∕cm. With a 5 μm∕s scan speed and 3.5 μJ pulse energy in a high-dose regime, few-mode guiding was achieved in the waveguide at 800 nm signal injection wavelength. This is due to a combination of increased refractive index in the core of the trace and the appearance of a depressed cladding.

Formation of nanogratings driven by ultrafast laser irradiation in mid-IR heavy oxide glasses

“…Hence, to overcome this restriction imposed by silicate glasses and access the aforementioned mid-IR range, nonsilicate glass matrices must be employed, such as chalcogenides [25], fluorides [26], or heavy oxides [27]. Among these potential optical materials, heavy metal oxide glasses (HMO), and more specifically barium gallo-germanate (BGG) glasses appear as promising candidates as they are chemically stable, manufacturable by conventional means (melt-quenching), mechanically resistant [28], and can exhibit an extended transmission in the IR range up to 7-8 μm [29].…”

Photosensitivity of barium germano-gallate glasses under femtosecond laser direct writing for Mid-IR applications

“…This operating wavelength window is interesting in the 3D manufacturing of miniaturized, low weight and cost optical systems, for civilian (domotics, smartphone, automobile) but also security and military applications (vehicles steering, survey, weapons guidance, unmasking, countermeasure identification). Hence, to circumvent this restriction imposed by silica / silicate glasses and access the Mid-infrared (Mid-IR) range (up to 5-8 µm), non-silicate glass matrices must be employed, such as chalcogenides [12][13][14], fluorides [15], or heavy oxides [16]. Among these potential candidates, heavy metal oxide (HMO) glasses can exhibit an extended transmission in the IR range up to 7-8 μm.…”

Femtosecond laser direct inscription of mid-IR transmitting waveguides in BGG glasses

“…Among the other potential optical materials, heavy metal oxide (HMO) glasses represent attractive hosts for mid-IR photonic devices as they are mechanically resistant, chemically stable and exhibit an extended transmission in the infrared spectra up to 7-8 μm. To date, the photosensitivity to fs pulses of only a few HMO glasses has been studied [10] and the direct inscription of low-loss (< 0.5 dB/cm) single mode waveguides operating at a wavelength higher than 1.03 μm has yet to be made. Among the HMO glasses, the germanate family forms an intriguing group whose response to femtosecond laser pulses has been, to the best our knowledge, left unexplored.…”