The Photochemistry of Organic Materials for Photonic Devices

<p>Optically active organic chromophores have attracted much interest in recent years for their potential for use in photonic devices. Chromophores such as compound (1) have been found to have a very high second order nonlinear susceptibility ( β ) value of 650 × 10⁻³⁰esu in dimethyl formamide.¹ The performance of 1 in a polymer film is much lower than this due to the formation of aggregates which hinder the poling process necessary to ensure a noncentrosymmetric arrangement of the molecules in order to display second order nonlinear behaviour. The molecular aggregation behaviour of a set of second order nonlinear compounds based on compound 1 have been studied in this thesis. These compounds share the backbone shown in figure 1 with pendant groups added to the R₁ R₂ and R₃ positions, with the aim of finding substituent groups that can be added to the optically active merocyanine backbone that reduce the aggregation and increase the solubility of the compounds. This in turn will make them more suitable for use in photonics devices. It was found that a C₁₁H₂₃ alkyl chain added to the R₃ position made the largest contribution to decreasing aggregation. Bulky groups on the R₁ and R₂ positions also reduced aggregation. As a result compounds 5 and 8, with R₃ = C₁₁H₂₃ and bulky groups attached displayed the least aggregation of the compounds studied. ¹ See Figure 1 (pg. i): Merocyanine backbone with substituent positions marked.</p>

The Photochemistry of Organic Materials for Photonic Devices

<p>Optically active organic chromophores have attracted much interest in recent years for their potential for use in photonic devices. Chromophores such as compound (1) have been found to have a very high second order nonlinear susceptibility ( β ) value of 650 × 10⁻³⁰esu in dimethyl formamide.¹ The performance of 1 in a polymer film is much lower than this due to the formation of aggregates which hinder the poling process necessary to ensure a noncentrosymmetric arrangement of the molecules in order to display second order nonlinear behaviour. The molecular aggregation behaviour of a set of second order nonlinear compounds based on compound 1 have been studied in this thesis. These compounds share the backbone shown in figure 1 with pendant groups added to the R₁ R₂ and R₃ positions, with the aim of finding substituent groups that can be added to the optically active merocyanine backbone that reduce the aggregation and increase the solubility of the compounds. This in turn will make them more suitable for use in photonics devices. It was found that a C₁₁H₂₃ alkyl chain added to the R₃ position made the largest contribution to decreasing aggregation. Bulky groups on the R₁ and R₂ positions also reduced aggregation. As a result compounds 5 and 8, with R₃ = C₁₁H₂₃ and bulky groups attached displayed the least aggregation of the compounds studied. ¹ See Figure 1 (pg. i): Merocyanine backbone with substituent positions marked.</p>

THE PHYSICAL BASIS FOR THE USE OF REFLECTIVE VOLUME HOLOGRAMS IN RADIO PHOTONICS DEVICES

Предлагается технология создания устройств радиофотоники на основе использования в них объемных отражательных голограмм. Построена математическая модель взаимосвязи параметров радиосигнала и пространственно-спектрального распределения интенсивности оптического поля в плоскости интерферограммы, формируемой световыми потоками, дифрагировавшими на объемной отражательной голограмме. Проведен анализ чувствительности параметров интерферограммы, формируемой в голографическом радиофотонном устройстве. The technology of creating radio-photonics devices based on the use of volume reflective holograms is proposed. A mathematical model of the relationship between the parameters of the radio signal and the spatial-spectral distribution of the optical field intensity in the plane of the interferogram formed by light fluxes diffracted on the volume hologram is constructed. The sensitivity of the parameters of the interferogram generated in a holographic radio photonic device is analyzed.

Microring Mixers and Tunable Filters in Silicon Photonics (Project Report 1201308-Y3)

The main goal of this NSF-funded project [1201308 - Year 3] is to develop integrated photonics devices based on silicon photonics which can be used for compact and efficient nonlinear classical and quantum photonics applications. During the third year of this project, we demonstrated the combination of an on-chip ring mixer and a tunable filter.

From Classical to Quantum Nonlinear Photonic Mixers on Silicon Microchips (Project Report 1201308-Y4)

The main goal of this NSF-funded project [1201308 - Year 4] is to develop an integrated photonics devices based on silicon photonics which can be used for compact and efficient nonlinear classical and quantum photonics. We demonstrated tunable photon-pair generation at room temperature from a high-Q Si microring resonator and coupled-resonator optical waveguide devices.

Passively mode locked thulium and thulium/holmium doped fiber lasers using MXene Nb2C coated microfiber

As a result of the emergence of two-dimensional (2D) materials for various opto-electronics applications, a new class of materials named MXenes have been attracting interests due to their outstanding nonlinear properties. In this work, an MXene niobium carbide (Nb2C) was proposed and demonstrated as a saturable absorber to induce mode-locking in thulium- and thulium/holmium-doped fiber lasers. The Nb2C solution was first prepared using the liquid exfoliation technique, and then deposited onto a microfiber for integration into the laser cavity. Stable mode-locking operation was observed in both laser cavities, where the center wavelengths of the laser were recorded at 1944 nm for the TDFL and 1950 nm for the THDFL. The generated pulses in the TDFL and THDFL had repetition rates of 9.35 and 11.76 MHz respectively, while their corresponding pulse widths were 1.67 and 1.34 ps. Both of the lasers were highly stable, having SNR values of more than 52 dB and showed no major fluctuations when tested for their long-term stabilities. The results demonstrate an excellent performance of the Nb2C as a saturable absorber, offering opportunities to further explore MXenes for future photonics devices.