We propose, for the first time to our knowledge, the theoretical investigation of silicon nanocrystals-based sandwiched slot waveguides which are dispersion-engineered for exciting optical solitons inside very short structures (only 1.2 mm long). Several parametric simulations have been performed by means of finite element method in order to individuate the best waveguide cross-sections for achieving an anomalous dispersion regime around 1550 nm.

We present a review of the theoretical models and experimental verification of the single-section Fabry-Perot mode-locked semiconductor lasers based on multiple-spatial-mode (MSM) coupling. The mode-locked operation at the repetition rates of 40 GHz and higher and the pulse width of a few picoseconds are confirmed by the intensity autocorrelation, the fast photo detection and RF spectrum, and the optical spectral interference measurement of ultrafast pulse. The spatial mode coupling theory of single-section Fabry-Perot mode-locked semiconductor lasers is also reviewed, and the results are compared with the experimental observations. The small signal modulation response of these lasers, which exhibits high-frequency responses well beyond the relaxation oscillation resonance limit, is also modeled theoretically, and the simulation is verified by the experimental measurements.

Optical waveguides were fabricated on z‐cut stoichiometric LiTaO3 (SLT) by using the proton‐exchange method. The surface index change for the extraordinary ray on the SLT substrate resulting from the proton exchange was 0.017, which coincided well with congruent LiTaO3 substrates. The proton exchange coefficient in the SLT was 0.25 × 10−12 cm2/s. The application of the SLT waveguide to a quasi‐velocity‐matched travelling‐wave electrooptic modulator with periodically polarization‐reversed structure is also reported.

MgO:LiNbO3 is an attractive nonlinear‐optic crystal for quasiphasematched (QPM) nonlinear‐optic devices. This paper reports a new formation method of domain‐inverted gratings for QPM in MgO:LiNbO3. Domain inversion of MgO:LiNbO3 by voltage application under UV light was characterized, and reduction of the voltage required for inversion was demonstrated. Results of voltage application under periodic UV light suggested that suppression of excess lateral expansion of the domain inverted regions on −Z surface was crucial for domain‐inverted grating formation. Voltage application to a crystal with a photoconductive cladding layer under periodic UV light was proposed. The cladding layer suppressed the expansion, and the domain‐inverted gratings with period of 18 μm and area of 25 × 5 mm2 were obtained. The formation method does not require the photolithography process and allows the formation by voltage application at room temperature, and therefore, is quite simple and productive.

We discuss a new method to design traveling‐wave electrooptic modulators with controlled frequency responses using nonperiodically polarization‐reversed structure. Using our method, the frequency responses of both magnitude and phase of modulation index are controllable. Several electrooptic modulators for advanced modulation formats such as duobinary modulation and wideband single‐sideband modulation are proposed.

Polycrystalline silicon thin‐film solar cells on glass obtained by solid‐phase crystallization (SPC) of PECVD‐deposited a‐Si precursor diodes are capable of producing large‐area devices with respectable photovoltaic efficiency. This has not yet been shown for equivalent devices made from evaporated Si precursor diodes (“EVA” solar cells). We demonstrate that there are two main problems for the metallization of EVA solar cells: (i) shunting of the p‐n junction when the air‐side metal contact is deposited; (ii) formation of the glass‐side contact with low contact resistance and without shunting. We present a working metallization scheme and first current‐voltage and quantum efficiency results of 2 cm2 EVA solar cells. The best planar EVA solar cells produced so far achieved fill factors up to 64%, series resistance values in the range of 4‐5 Ωcm2, short‐circuit current densities of up to 15.6 mA/cm2, and efficiencies of up to 4.25%. Using numerical device simulation, a diffusion length of about 4 μm is demonstrated for such devices. These promising results confirm that the device fabrication scheme presented in this paper is well suited for the metallization of EVA solar cells and that the electronic properties of evaporated SPC poly‐Si materials are sufficient for PV applications.

One main efficiency loss in industrial solar cells is the shading of the cell caused by the metal front side contacts. With the aerosol‐printing technique plus an additional light‐induced plating (LIP) step, not only is the geometrical contact width narrowed compared to screen‐printed contacts but also the shape of the finger changes. In this work, the effective shading of different finger types is analysed with two different measurement methods. The essential parameter for characterising the finger is the effective width which can be reduced drastically compared to the geometrical width due to total internal reflection at the glass‐air layer and the reflection from the roundish edges of the contact fingers into the cell. This parameter was determined with different methods. It could be shown that for aerosol‐printed fingers the effective (optical) width is only 38% of its geometrical width, while for standard screen‐printed fingers it is 47%. The measured values are compared to a theoretical model for an aerosol‐printed and plated finger and are in good agreement.

The changes in open-circuit voltage (Voc), short-circuit current density (Jsc), and internal quantum efficiency (IQE) of aLuminum induced crystallization, ion-assisted deposition (ALICIA) polycrystalline silicon thin-film solar cells on low-temperature glass substrates due to rapid thermal anneal (RTA) treatment and subsequent remote microwave hydrogen plasma passivation (hydrogenation) are examined. Voc improvements from 130 mV to 430 mV, Jsc improvements from 1.2 mA/cm2 to 11.3 mA/cm2, and peak IQE improvements from 16% to > 70% are achieved. A 1-second RTA plateau at 1000°C followed by hydrogenation increases the Jsc by a factor of 5.5. Secondary ion mass spectroscopy measurements are used to determine the concentration profiles of dopants, impurities, and hydrogen. Computer modeling based on simulations of the measured IQE data reveals that the minority carrier lifetime in the absorber region increases by 3 orders of magnitude to about 1 nanosecond (corresponding to a diffusion length of at least 1 μm) due to RTA and subsequent hydrogenation. The evaluation of the changes in the quantum efficiency and Voc due to RTA and hydrogenation with computer modeling significantly improves the understanding of the limiting factors to cell performance.

We study the properties of various anisotropic left-handed slab waveguides. The analysis is extended to anisotropic μ-negative slab waveguides. The possible existence of the plasmon modes in various anisotropic slab waveguide configurations is discussed. An FDTD program is developed to investigate the potential device applications of these anisotropic structures. A new signal detector and a two-channel harmonic separator multiplexer are designed employing the μ-negative slab waveguide.