Octave Spanning Supercontinuum in Titanium Dioxide Waveguides

Abstract

We report on the experimental generation of an octave-spanning supercontinuum in a 2.2 cm-long titanium dioxide optical waveguide with two zero dispersion wavelengths. The resulting on-chip supercontinuum reaches the visible wavelength range as well as the mid-infrared region by using a femtosecond fiber laser pump at 1.64 µm.

TiO2 microring resonators with high Q and compact footprint fabricated by a bottom-up method

“…Titanium dioxide (TiO 2 ) has recently evolved as a promising candidate for photonic integrated circuits (PICs) by possessing high linear and nonlinear indices, a large bandgap (>3 eV), a uniquely negative thermo-optic coefficient, and a large transparency window from visible to mid infrared wavelengths [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Besides, the possible compatibility with the mature silicon complementary metal oxide semiconductor (CMOS) fabrication process also endorses TiO 2 -based PICs in terms of scalable manufacturing [19].…”

“…Several methods have been demonstrated to pattern TiO 2 waveguides, including ion implantation [1], wet etching [2], dry etching [3][4][5][6][7][8][9][10][11][12][13], and lift-off [14,15]. Among them, the top-down method, in which TiO 2 film is first deposited and then selectively etched with a mask, has normally been used.…”

Development of low-loss TiO2 waveguides

“…The demand for photonic integrated circuits is rapidly increasing. TiO 2 is an emerging material for integrated photonics, which has received increasing interest in the last few years [1][2][3][4][5]. Its high refractive index (i.e., 2.2-2.3 for amorphous layers and even higher when in its crystalline phases anatase or rutile [1]) permits the design of compact integrated circuits.…”

“…TiO 2 exhibits a high non-linear refractive index, approximately 3 times larger than that of silicon nitride [8]. Several non-linear processes have been recently demonstrated in TiO 2 waveguides, such as third harmonic generation [13], supercontinuum generation [2], spectral broadening [14] and four wave mixing [5].…”

Low loss TiO2 channel waveguides

“…The possibility to dope TiO 2 with, for example, rare earth ions or Si [4][5][6][7] makes TiO 2 promising for active on chip devices. TiO 2 exhibits a high non-linear refractive index, resulting in the demonstration of third harmonic generation [8], supercontinuum generation [9], spectral broadening [10] and four-wave mixing [11]. The negative thermo-optic coefficient [12] allows for the realization of athermal devices [13], by combining TiO 2 with, for example, Si 3 N 4 [14,15] or silicon [16,17].…”