Ann-Kuo Chu

Four-wave-mixing in the loss low submicrometer Ta₂O₅ channel waveguide.

A degenerate four-wave-mixing (FWM) operation in the Ta2O5 submicrometer channel waveguide has been successfully demonstrated. The propagation loss of 1.5  dB/cm and total insertion loss of 5.1 dB are realized in a 12.6 mm long waveguide with inverse taper structure. The wavelength and quadratic pumping power-dependent measurements on optical transmission confirm FWM performance and characterize the nonlinearity of waveguide. The conversion efficiency of -50  dB at coupled pump power of 40 mW is observed, suggesting that the nonlinear refractive index of Ta2O5 waveguide at 1550 nm is estimated to be 1×10(-14)  cm2/W. Our primary results indicate that the Ta2O5 submicrometer channel waveguide has great potential in developing nonlinear waveguide applications.

ITO DBR Electrodes Fabricated on PET Substrate for Organic Electronics

A conductive distributed Bragg reflector (DBR) fabricated on PET substrate using the single indium tin oxide (ITO) material is proposed. The large index contrast of the DBRs was obtained by depositing alternating layers of dense and porous ITO films. The high refractive index of the dense ITO films was achieved by long-throw radio-frequency magnetron sputtering technique at room temperature. On the other hand, the porous ITO films with low refractive index were fabricated by supercritical CO2 (SCCO2) treatment at 60 °C. The index contrast of the dense and porous ITO films as larger as 0.59 at blue spectral range was obtained. For the 4.5-period ITO DBR fabricated on PET substrate, the reflectance and sheet resistance of 85.1% and 47 Ω/◻ were achieved at 475 nm.

Low-loss and high-Q Ta(2)O(5) based micro-ring resonator with inverse taper structure.

A low-loss and high-Q Ta(2)O(5) based micro-ring resonator is presented. The micro-ring resonator and channel waveguide with core area of the 700 by 400 nm(2) were fabricated on amorphous Ta(2)O(5) thin films prepared by reactive sputtering at 300°C and post annealing at 650°C for 3 hours. The Ta(2)O(5) micro-ring resonator with a diameter of 200 μm was coupled to the channel waveguide with a coupled Q up to 38,000 at a 0.9 μm coupling gap. By fitting the transmission spectrum of the resonator, the extracted loss coefficient inside the ring cavity and transmission coefficient of TE mode were 8.1dB/cm and 0.9923, leading to the estimated unloaded Q of higher than 44,000. In addition, based on the cut-back method, the propagation loss and the coupling loss of Ta(2)O(5) channel waveguide with an inverse taper were 1.5dB/cm and 3.2 dB, respectively. The proposed Ta(2)O(5) technology offers an unique alternative for fabricating high performance guided wave devices, and may well lead to novel applications in photonic integrated circuits.

Self-phase modulation in highly confined submicron Ta 2 O 5 channel waveguides

Optical spectra broadening as a result self-phase modulation in a channel waveguide fabricated on a high quality tantalum pentoxide (Ta₂O₅) film by using RF sputtering is measured. The full-width at half maximum of the optical spectra for transverse electric (TE)/transverse magnetic (TM) polarizations of 42.5/31.7 nm is obtained using pulses of 10 nm at a wavelength of 800 nm with a peak-coupled power of 43.77 W. The nonlinear Kerr coefficients of 2.14 × 10^-14 cm²/W and 1.92 × 10^-14 cm²/W for TE and TM polarizations, respectively, are then extracted from the experiments using a theoretical model based on the method of moments. The obtained results on the nonlinearity further suggest that Ta₂O₅ is a promising material to develop nonlinear waveguide devices for integrated photonics.

Parametric frequency conversion in Ta 2 O 5 based micro-ring cavity

Nonlinear wavelength generations by using the optical waveguides are more compact, low cost, and efficient than using the traditional solid state systems [1], and the generated broadband light sources can be utilized in optical coherence tomography, frequency metrology, optical communications, and many other. In this work, the high quality of tantalum pentoxide (Ta<inf>2</inf>O<inf>5</inf>) micro-ring resonator has been fabricated to realize the low power parametric frequency conversion in the communication region. Figure 1 shows the illustration and scanning electron microscope (SEM) image of Ta<inf>2</inf>O<inf>5</inf> based micro-ring resonator. The width/height of the ring waveguides is set as 1.5μm/0.7μm for the anomalous dispersion, which is a key element to minimize the phase mismatch in the parametric frequency conversion process. By fitting the transmission spectrum of the Ta2O5 ring resonator, the load quality factor is ∼50000 and the loss coefficient is ∼0.5cm⁻¹. The unload quality factor is estimated to be ∼180000, which is the best record of Ta<inf>2</inf>O<inf>5</inf> based micro-ring resonator [2].

Low-loss submicron Ta2O5 optical waveguide and nonlinear optical application

The low-loss and CMOS compatible Ta₂O₅ based optical waveguide has been demonstrated. The quality factor of 50,000 in the Ta₂O₅ micro-ring resonator is fabricated. Moreover, the four-wave-mixing has been realized in the submicron Ta₂O₅ channel waveguide.

Thin WDM filters for low-cost optical triplexers on silicon benches

Optical triplexers using thin WDM filters and lensed fibers on silicon bench were proposed. The fiber-to-fiber insertion losses were less than 1.2 dB, and the power variations at 1.31/1.49/1.55 mum ports were less than 0.7 dB at 100degC.