Techn. Universiẗat, Diss., 2003--Berlin.

Techn. University, Diss., 2003--Dresden.

Essen, Universiẗat, Diss., 2004--Duisburg.

Segmented traveling wave electro-absorption modulators (TWEAMs) can provide a modulation speed above 100 Gb/s, which is needed in new optical communication networks. In the EU-project TWILIGHT, KTH continues the design work of TWEAMs in the EU-projects IPHOBAC and HECTO with the aim to design a new optical modulator to be integrated with an electronic layer. The structure of the modulator has to be changed in order to make it compatible with the integration technology that will be used in the project. Like in previous projects, the PSPICE software is an important tool for the design work. The past studies left a large amount of different models and test data. This thesis has been focused on studying these models and data to see if they can help the future work in the project. This includes the comparison of the geometrical dimensions, the microwave properties, and the simulation results with the fabricated modulators in the past projects. The electrical parameters are also critical for the design work, especially the capacitance which determines the impedance of the modulator. Since the TWILIGHT project needs a new design of the modulator, the calculation of these parameters will change. This thesis contains a study how this can be done and discusses the parameters for the new TWEAM design. / Segmenterade elektroabsorptionsmodulatorer för vandrande vågor (TWEAMs) kan ge moduleringshastigheter över 100 Gb/s, vilket behövs i nya optiska kommunikationsnätverk. I EU-projektet TWILIGHT fortsätter KTH designarbetet av TWEAMs i EU-projektet IPHOBAC och HECTO med syfte att designa en ny optisk modulator som ska integreras med ett elektronik-lager. Modulatorns struktur måste ändras för att den ska bli kompatibel med integrationstekniken som ska användas i projektet. Precis som i tidigare projekt är PSPICE-mjukvaran ett viktigt verktyg för designarbetet. Den tidigare studierna lämnade en stor mängd olika modeller och testdata. Detta examensarbete har fokuserat på att studera dessa modeller och data för att se om de kan hjälpa det framtida arbetet i projektet. Detta inkluderar jämförelsen av de geometriska dimensionerna, mikrovågsegenskaperna och simuleringsresultaten med de tillverkade modulatorerna i tidigare projekt. De elektriska parametrarna är också kritiska för konstruktionsarbetet, speciellt kapacitansen som bestämmer modulatorns impedans. Eftersom TWILIGHT-projektet har en ny design för modulatorn, ändras beräkningen av dessa parametrar. Detta examensarbete innehåller en studie hur detta kan göras och diskuterar parametrarna för den nya TWEAM-designen.

We have presented a thorough experimental investigation of electroabsorption spectroscopy on quasi-one-dimensional organic molecular crystals such as PTCDA and MePTCDI vapor deposited thin films to clarify the involvement of the charge-transfer exciton in the lowest excited state. By a self-built experimental setup, two kinds of electroabsorption measurements, called "perpendicular" and "parallel" measurements, were conducted at room temperature in ambient air. The crystalline texture of PTCDA and MePTCDI thin film samples are characterized by X-ray diffraction measurements. Current-voltage, capacitance-frequency and capacitance-voltage measurements are performed to clarify the electric field distribution inside organic layers. The results from electrical measurements show that only under certain conditions (electroabsorption measurements with proDC bias), the perpendicular and parallel electroabsorption meaurements can be directly compared. The electroabsorption spectra of MePTCDI and PTCDA thin films can be interpreted by neither pure Frenkel exciton nor pure charge-transfer exciton model. Essential features of electroabsorption spectra of MePTCDI and PTCDA thin films can be understood by the the mixture of Frenkel and charge-transfer exciton model. However, there is still a discrepancy in the directional properties of electroabsorption signals between experimental results and modle calculations. This small discrepancy suggests that a full interpretation of electroabsorption spectra of quasi-one-dimensional organic molecular crystals needs further experimental and theoretical investigations.

We have presented a thorough experimental investigation of electroabsorption spectroscopy on quasi-one-dimensional organic molecular crystals such as PTCDA and MePTCDI vapor deposited thin films to clarify the involvement of the charge-transfer exciton in the lowest excited state. By a self-built experimental setup, two kinds of electroabsorption measurements, called "perpendicular" and "parallel" measurements, were conducted at room temperature in ambient air. The crystalline texture of PTCDA and MePTCDI thin film samples are characterized by X-ray diffraction measurements. Current-voltage, capacitance-frequency and capacitance-voltage measurements are performed to clarify the electric field distribution inside organic layers. The results from electrical measurements show that only under certain conditions (electroabsorption measurements with proDC bias), the perpendicular and parallel electroabsorption meaurements can be directly compared. The electroabsorption spectra of MePTCDI and PTCDA thin films can be interpreted by neither pure Frenkel exciton nor pure charge-transfer exciton model. Essential features of electroabsorption spectra of MePTCDI and PTCDA thin films can be understood by the the mixture of Frenkel and charge-transfer exciton model. However, there is still a discrepancy in the directional properties of electroabsorption signals between experimental results and modle calculations. This small discrepancy suggests that a full interpretation of electroabsorption spectra of quasi-one-dimensional organic molecular crystals needs further experimental and theoretical investigations.