Ultrafast laser fabrication of low-loss waveguides in chalcogenide glass with 065  dB/cm loss

McMillen, Ben; Zhang, Botao; Chen, Kevin P.; Benayas, Antonio; Jaque, Daniel

doi:10.1364/ol.37.001418

Cited by 44 publications

(22 citation statements)

References 11 publications

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“…The nonlinear nature of the process makes it difficult to control and thus the waveguide inscription challenging [24,99]. It can distort the waveguide shape [26] or even entirely inhibit waveguide formation [100,101]. The Kerr nonlinearity results in an intensity-dependent refractive index change that follows the spatial intensity profile of the laser.…”

Section: Kerr Self-focusingmentioning

confidence: 99%

“…In order to mitigate the influence of nonlinear propagation effects, chirping the laser pulses to a few hundred femtoseconds up to a few picoseconds has been shown to be an effective means for the inscription of waveguides in highly nonlinear media such as lithium niobate [109], zinc selenide [100] and chalcogenide glass [101]. Moreover, complex temporal pulse envelopes can be used to spatially optimise the energy deposition, thereby simultaneously compensating for spherical aberrations and nonlinear pulse propagation [110].…”

Section: Kerr Self-focusingmentioning

confidence: 99%

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Ultrafast-laser-inscribed 3D integrated photonics: challenges and emerging applications

2015

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Since the discovery that tightly focused femtosecond laser pulses can induce a highly localised and permanent refractive index modification in a large number of transparent dielectrics, the technique of ultrafast laser inscription has received great attention from a wide range of applications. In particular, the capability to create three-dimensional optical waveguide circuits has opened up new opportunities for integrated photonics that would not have been possible with traditional planar fabrication techniques because it enables full access to the many degrees of freedom in a photon. This paper reviews the basic techniques and technological challenges of 3D integrated photonics fabricated using ultrafast laser inscription as well as reviews the most recent progress in the fields of astrophotonics, optical communication, quantum photonics, emulation of quantum systems, optofluidics and sensing.

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Section: Kerr Self-focusingmentioning

confidence: 99%

Section: Kerr Self-focusingmentioning

confidence: 99%

Ultrafast-laser-inscribed 3D integrated photonics: challenges and emerging applications

2015

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“…These techniques, combined with adjustment of other processing parameters such as writing speed, pulse energy, and repetition rate, have produced nearly symmetric waveguides with propagation losses as low as 0.65 dB∕cm at 1560 nm [18]. With this exceptionally low propagation loss and precise control over the waveguide cross section, this technique provides a new avenue for fabricating complex optical structures in highly nonlinear materials.…”

mentioning

confidence: 99%

“…The beam was then circularly polarized before being delivered to the ChG substrate with the objective, forming a focus 275 μm beneath the surface. Spatial beam shaping, in combination with longer pulse duration, allows for mitigation of beam distortions at the focus, resulting in a nearly circular waveguide cross section in GLS ChG glass [18]. Moreover, full control over the size and shape of the waveguide cross section is realized by adjusting the distance between the two cylindrical lenses, thereby tuning the astigmatic difference.…”

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confidence: 99%

Ultrafast laser fabrication of Bragg waveguides in chalcogenide glass

McMillen

Huang

et al. 2014

Opt. Lett.

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Bragg waveguides are fundamental components in photonic integrated circuits and are particularly interesting for mid-IR applications in high index, highly nonlinear materials. In this work, we present Bragg waveguides fabricated in bulk chalcogenide glass using an ultrafast laser. Waveguides with near circularly symmetric cross sections and low propagation loss are obtained through spatial and temporal beam shaping. Using a single-pass technique, the waveguide and Bragg structure are formed at the same time. First through sixth order gratings with strengths of up to 25 dB are realized, and performance is evaluated based on the modulation duty cycle of the writing beam. Chalcogenide (ChG) glasses are known for their excellent mid-IR transparency and large nonlinear refractive indices of up to 1000 times that of fused silica [1,2]. These unique traits make them attractive in a wide range of applications. In particular, ChG glasses are suitable substrate materials for fabricating photonic integrated circuits (PICs), due to inherently large χ 3 nonlinearities with ultrafast response times and low two-photon absorption at telecom wavelengths. These properties become especially important in applications such as high-data-rate signal processing [3][4][5]. In such PIC devices, Bragg waveguides are often employed as basic building blocks, enabling operations such as 2R regeneration [6,7], and all-optical switching [8]. Fabrication of these structures generally relies on thin film deposition and various photolithography schemes. However, thin-film processes incur restrictions when building multilayer structures for complex optical interconnects by limiting devices to a planar geometry. Ultrafast laser writing offers great design flexibility with its capability for making three-dimensional structures [9,10] and is a proven technique to form high-quality waveguides in bulk optical substrates. Extensions of this technology have also been applied to the fabrication of Bragg waveguides in fused silica using several approaches, such as the point-by-point technique [11][12][13], and the multiscan technique [14]. Applying these methods to ChG glasses, however, presents a unique design challenge. The high refractive index of these materials induces spherical aberrations at the focus of the writing beam, which are further compounded by nonlinear effects brought about by high-intensity laser pulses. These interactions often lead to self-focusing and filamentation, producing highly asymmetrical waveguides with an elongated cross section and multiple guiding regions [15]. Mitigation of these effects is essential for fabricating high-quality waveguides in ChG glasses.Recently, it has been demonstrated that temporal [16] and spatial beam shaping [17] may be used to control the size and shape of the cross section of a laser-written waveguide. These techniques, combined with adjustment of other processing parameters such as writing speed, pulse energy, and repetition rate, have produced nearly symmetric waveguides with propagation losses ...

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“…However, these challenges could be overcome by minimizing the spatial and temporal distortion of the writing beam by means of beam shaping and temporal pulse tuning. Recently, we have demonstrated ultrafast laser fabrication of high-quality waveguide in ChG glasses with highly symmetric waveguide profile and 0.65 dB∕cm propagation loss at 1550 nm [9]. This opens the possibility of producing 3D nonlinear lightwave circuits in bulk materials.…”

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confidence: 99%

Nonlinear lightwave circuits in chalcogenide glasses fabricated by ultrafast laser

Huang

Wang

et al. 2014

Opt. Lett.

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This Letter reports a nonlinear directional waveguide coupler written by ultrafast laser in gallium lanthanum sulfide chalcogenide glass. The nonlinear waveguide device is tested with laser pulses input in two orthogonal polarizations, and all optical switching at 1040 nm between the two coupled waveguides is observed at a peak fluence of 16 GW∕cm 2 . The spectra and autocorrelation measurement from the waveguide outputs show dominant nonlinear effects and negligible dispersion for light propagation in both channels. . Although a number of excellent waveguide devices have been demonstrated using thin-film based approach, performance of photonic devices is extremely sensitive to properties of ChG films. In many situations, thin optical films produced by state-of-the-art deposition techniques do not possess optical qualities as good as those found in bulk substrates. This challenge in fabrication diminishes the possibility of building three-dimensional photonic structures through the conventional layer-by-layer lithography technique. Ultrafast laser writing technique is another alternative to produce waveguide devices in ChG glasses. The unique trait for this technique is its ability to fabricate arbitrary complex structures and three-dimensional (3D) integrated circuits in bulk optical glass with proven optical quality [4]. It has been proven in fabricating both linear [5,6] and nonlinear [7,8] optical devices in silica.Although it is beneficial to use highly nonlinear materials to fabricate nonlinear optical devices, it is also a challenge to process such materials with ultrafast laser irradiation. This is because the focused writing beam with high peak intensity could experience large distortion in the material, resulting in an enlarged modification area and undesired material changes along the direction of the writing beam. However, these challenges could be overcome by minimizing the spatial and temporal distortion of the writing beam by means of beam shaping and temporal pulse tuning. Recently, we have demonstrated ultrafast laser fabrication of high-quality waveguide in ChG glasses with highly symmetric waveguide profile and 0.65 dB∕cm propagation loss at 1550 nm [9]. This opens the possibility of producing 3D nonlinear lightwave circuits in bulk materials.In this Letter, we present a nonlinear directional coupler (NLDC) fabricated in gallium lanthanum sulfide (GLS) chalcogenide glass by ultrafast laser. The selection of GLS glass is based on its good thermal stability and its nontoxic nature [10,11]. The performance of the NLDC is investigated at two orthogonal input polarizations. The output power fractions of the two ports of the NLDC vary with the peak intensity of the input laser pulses, and a clear all-optical switching is observed at 16 GW∕cm 2 . The output spectra and the autocorrelation traces from both ports show that the nonlinear effect is dominant in the pulse propagation while the linear dispersion can be neglected.The NLDC in GLS ChG glass is written using a Coherent RegA 9000 laser system, w...

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Ultrafast laser fabrication of low-loss waveguides in chalcogenide glass with 065 dB/cm loss

Cited by 44 publications

References 11 publications

Ultrafast-laser-inscribed 3D integrated photonics: challenges and emerging applications

Ultrafast-laser-inscribed 3D integrated photonics: challenges and emerging applications

Ultrafast laser fabrication of Bragg waveguides in chalcogenide glass

Nonlinear lightwave circuits in chalcogenide glasses fabricated by ultrafast laser

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