We report the fabrication and characterization of high index contrast (Δn≈0.9) GeTe4 channel waveguides on ZnSe substrate for evanescent-field-based biosensing applications in the mid-IR spectral region. GeTe4 films were deposited by RF sputtering and characterized for their structure, composition, transparency, and dispersion. The lift-off technique was used to pattern the waveguide channels. Waveguiding from 2.5-3.7 and 6.4-7.5 μm was demonstrated, and mode intensity profile and estimated propagation losses are given for the 3.5 μm wavelength.

We demonstrate multiplexed terahertz emitters that exhibits 2 THz bandwidth that do not require an external bias. The emitters operate under uniform illumination eliminating the need for a micro-lens array and are fabricated with periodic Au and Pb structures on GaAs. Terahertz emission originates from the lateral photo-Dember effect and from the different Schottky barrier heights of the chosen metal pair. We characterize the emitters and determine that most terahertz emission at 300 K is due to band-bending due to the Schottky barrier of the metal.Comment: 4 pages, 6 figure

Received Month X, XXXX; revised Month X, XXXX; accepted Month X, XXXX; posted Month X, XXXX (Doc. ID XXXXX); published Month X, XXXX A waveguide laser in an ytterbium doped tantalum pentoxide film is reported. The waveguide is formed of a rib of sputtered tantalum pentoxide on top of oxidized silicon with an over-cladding of silica. Emission at a wavelength of 1025 nm was achieved with an absorbed pump power threshold and slope efficiency of ≈ 29 mW and 27% respectively for a cavity formed by a high reflector mirror and an estimated 12% Fresnel reflection from the bare end-face at the output. © 2015 Optical Society of America OCIS Codes: (140.3615) Lasers, ytterbium, (140.3380) Laser materials, (230.7380) Waveguides, channeled, Lasers doped with ytterbium (Yb) ions exhibit long excited-state lifetime yielding high gain efficiency and low pump power thresholds, low quantum defect providing good power-handling ability and low-cost optical pumping using semiconductor sources due to broad absorption at wavelengths near 980 nm. [17], leading to the potential of multi-functional, massproducible, integrated optical circuits on silicon. The material also shows a large third-order non-linearity (n2 ≈ 7.25 ×10 -19 m 2 /W at λ ≈ 980 nm) [18] with potential for alloptical processing, and a high-refractive index (n ≈ 2.124 at λ ≈ 980 nm) [19] enabling compact photonic circuits with low bend loss. A high index makes possible submicron waveguide mode sizes which are useful for nonlinear interactions and low laser thresholds and also makes possible the development of ring resonators that require tight bend radii. Furthermore, Ta2O5 offers high transparency and low two-photon absorption in the NIR compared with silicon, better rare-earth compatibility compared with silicon and silicon nitride, and high indexcontrast and large third-order nonlinearity compared with aluminium oxide (n ≈ 1.726; n2 ≈ 0.31 ×10 -19 m 2 /W at λ ≈ 1064 nm [20]). As the high nonlinearity is coupled with broad fluorescence bandwidth [14], this material is particularly attractive for the realization of on-chip frequency comb generation and mode-locked lasers.In this letter, we present an integrated waveguide laser in Yb-doped Ta2O5 (Yb:Ta2O5) on silicon, Fig. 1 including characteristics such as slope efficiency and threshold with respect to absorbed pump power and lasing spectrum. Detailed fabrication procedures, absorption and emission cross-sections and other materials properties were previously reported in [14]. From that study many key properties were established such as fluorescence emission spanning between 990 nm and 1090 nm with an estimated peak emission cross-section of 2.9 ± 0.7 ×10 -20 cm 2 (at λ = 976 nm) seen in Fig. 2, a peak absorption cross-section of 2.8 ± 0.2 ×10 -20 cm 2 (at λ = 975 nm), and luminescence lifetime of 260 ± 30 μs. These values showed that Yb:Ta2O5 is a promising material for continuous wave and modelocked lasing. In the present work, rib waveguides in Yb:Ta2O5 were designed to be single mode for wavelengths between...

Abstract:The design, fabrication and spectroscopic characterization of ytterbium-doped Ta 2 O 5 rib waveguide are described. The waveguides are fabricated on silicon substrates and operate in a single mode at wavelengths above 970 nm. The peak absorption cross-section was measured to be 2.75 × 10 −20 cm 2 at 975 nm. The emission spectrum was found to have a broad fluorescence spanning from 990 nm to 1090 nm with the fluorescence emission peak occurring at a wavelength of 976 nm. The excited-state life time was measured to be approximately 260 µs. Pollnau, "Low-threshold, highly efficient Gd 3+ , Lu 3+ co-doped KY(WO 4 ) 2 :Yb 3+ planar waveguide lasers," Laser Phys. Lett. 6(11), 800-805 (2009

Abstract:We report the linear and nonlinear characterization of low loss Yb:Ta 2 O 5 rib waveguides fabricated by using CMOS compatible processes on a SOI substrate. We report a nonlinear refractive index of 6.65x10 -18 m 2 /W measured at telecom wavelengths.