Polarization behaviour of femtosecond laser written waveguides in lithium niobate

Tejerina, Matías Rubén; Biasetti, Demian A.; Torchia, G. A.

doi:10.1016/j.optmat.2015.06.030

Cited by 8 publications

(9 citation statements)

References 12 publications

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“…An other interesting development was the depressed cladding waveguides in LiNbO3 [11,12], also called type III. The most important goal from this technique is the three-dimensional (3D) tailoring which boosts its applicability to many integrated photonics targets [13][14][15][16][17], see also [18] for type I 3D waveguides. The lithium niobate (LiNbO3) crystal has many interesting optical properties such as excellent non-linear, electro-optic, and piezo-optic coefficients and it is also broadly used for technological purposes, i.e.…”

Section: Introductionmentioning

confidence: 99%

Bending waveguides made in x-cut lithium niobate crystals for technological applications

Guarepi

Perrone

Aveni

et al. 2015

J. Micromech. Microeng.

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In this paper we analyse the performance of several designs of integrated optical deviators made in x-cut lithium niobate crystals by means of femtosecond laser writing using the double line approach. Straight and bent guiding structures have been designed and implemented using this technique. Well-confined propagation modes at communication wavelengths (1.55 μm) were conducted in these structures with acceptable overall losses (less than 2 dB cm−1). Further, a discussion about the optical propagation losses for curved and straight deviators devices is included in this work. At a low aperture angle (less than 0.2°), as expected, low losses were determined for both structures; however, a weak output light was observed for large angles (greater than 0.2°) in the straight optical circuits. In contrast, a smooth variation of the output was measured for the bent structures. The results presented in this paper support the possibility of the technological implementation of integrated optical circuits for optical communications fabricated with ultrashort laser writing in lithium niobate crystals. In addition, some hypotheses of loss mechanisms that are normally not considered are discussed in order to explain the differences between the measured values and predictions obtained by calculating with the usual models.

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Section: Introductionmentioning

confidence: 99%

Bending waveguides made in x-cut lithium niobate crystals for technological applications

Guarepi

Perrone

Aveni

et al. 2015

J. Micromech. Microeng.

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show abstract

“…Referring to z-polarized guided modes, it is reported in the literature that they are supported by this kind of femtosecond laser-written waveguides by launching 650, 800 and 1085 nm wavelengths [15,18]. In the current analysis, we could not measure z-polarized guided modes at 1550 nm wavelength, and accordingly no guided modes were obtained in simulations using retrieved Dn z field.…”

Section: Methods and Resultsmentioning

confidence: 60%

“…From the obtained n x (z, x) and n z (z, x), the supported guided modes for the different optical polarizations (E x and E z ) can be computed by solving the Helmholtz equation with the finite element method to compare them with experimentally guided modes [15,16].…”

Section: Methods and Resultsmentioning

confidence: 99%

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Testing a novel μ-Raman method to retrieve refractive index and density field from femtosecond laser-written optical waveguides

Tejerina

Torchia

2016

Appl. Phys. A

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In this work, we analysed the refractive index field and other local material properties of femtosecond laser-written waveguides properly combining a novel and direct Raman strategy, waveguides coupling and instrumented nano-indentation. At first, we measured a 2D Raman map within the cross section of femtosecond laser-written waveguides. Then, the Raman Phonon Deformation Constants of lithium niobate were employed to retrieve the strain and density variation from the A 1 (TO) phonon shifts in the analysed region. We test the results obtained with different combinations of phonons by computing the numerical guided modes and comparing them with those experimentally measured. As a relevant finding, we found that the combination of the A 1 (TO) 1 and A 1 (TO) 4 phonon shifting is the most proper one to compute strain, density and refractive index variation, almost in this kind of waveguide. Finally, a linear path across waveguides cross section was explored with instrumented nano-indentation and the expected variation of local density was detected through a softening of the elastic module observed in the region directly modified by the ultra-fast laser.

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“…Femtosecond laser processing is a promising technique for fabricating waveguides within a glass substrate as it can directly form 3-D micro structures in the substrate, [3][4][5][6][7] and in particular writing within lithium niobate with femtosecond laser pulses. [8][9][10][11][12][13][14][15] There are, however, upper limits where ablation or vaporization occurs within a material. The process of optically induced damage, ablation, or vaporization of the material is produced by avalanche breakdown, which is the primary mechanism for material degradation with pulsed lasers operating at pulses shorter than 1 µs with intensities in the range of 10 9 W/cm 2 to 10 12 W/cm 2 .…”

Section: Writing With Femtosecond Lasermentioning

confidence: 99%

Fabrication of waveguide spatial light modulators via femtosecond laser micromachining

et al. 2016

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We have previously introduced an anisotropic leaky-mode modulator as a waveguide-based, acousto-optic solution for spatial light modulation in holographic video display systems. Waveguide fabrication for these and similar surface acoustic wave devices relies on proton exchange of a lithium niobate substrate, which involves the immersion of the substrate in an acid melt. While simple and effective, waveguide depth and index profiles resulting from proton exchange are often non-uniform over the device length or inconsistent between waveguides fabricated at different times using the same melt and annealing parameters. In contrast to proton exchange, direct writing of waveguides has the appeal of simplifying fabrication (as these methods are inherently maskless) and the potential of fine and consistent control over waveguide depth and index profiles. In this paper, we explore femtosecond laser micromachining as an alternative to proton exchange in the fabrication of waveguides for anisotropic leaky-mode modulators.

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Polarization behaviour of femtosecond laser written waveguides in lithium niobate

Cited by 8 publications

References 12 publications

Bending waveguides made in x-cut lithium niobate crystals for technological applications

Bending waveguides made in x-cut lithium niobate crystals for technological applications

Testing a novel μ-Raman method to retrieve refractive index and density field from femtosecond laser-written optical waveguides

Fabrication of waveguide spatial light modulators via femtosecond laser micromachining

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