Highly efficient coupling between a monolithically integrated photonic crystal cavity and a bus waveguide

We experimentally demonstrate a new optical filter design comprising of a photonic crystal cavity and a low index bus waveguide which are monolithically integrated on a silicon-on-insulator (SOI) platform. We have fabricated oxide clad PhC cavities with a silicon nitride waveguide positioned directly above, such that there is an overlap between the evanescent tails of the two modes. We have realised an extinction ratio of 7.5dB for cavities with total Q of 50,000.Postprin

Electrically injected photonic-crystal nanocavities

Nano-emitters are the new generation of laser devices. A photonic-crystal cavity, which highly confines light in small volumes, in combination with quantum-dots can enhance the efficiency and lower the threshold of this device. The practical realisation of a reliable, electrically pumped photonic-crystal laser at room-temperature is, however, challenging. In this project, a design for such a laser was established. Its properties are split up into electrical, optical and thermal tasks that are individually investigated via various device simulations. The resulting device performance showed that with our design the quantum-dots can be pumped in order to provide gain and to overcome the loss of the system. Threshold currents can be as low as 10’s of μA and Q-factors in the range of 1000’s. Gallium arsenide wafers were grown according to our specifications and their diode behaviour confirmed. Photonic-crystal cavities were fabricated through a newly developed process based on a TiOₓ hard-mask. Beside membraned cavities, also cavities on oxidised AlGaAs were fabricated with help to a unique hard-mask removal method. The cavities were measured with a self-made micro-photoluminescence setup with the highest Q-factor of 4000 for the membrane cavity and a remarkable 2200 for the oxide cavity. The fabrication steps, regarding the electrically pumped photonic-crystal laser, were developed and it was shown that this device can be fabricated. During this project, a novel type of gentle confinement cavity was developed, based on the adaption of the dispersion curve (DA cavity) of a photonic-crystal waveguide. Q-factors of as high as 600.000 were measured for these cavities made in Silicon

Highly efficient optical filter based on vertically coupled photonic crystal cavity and bus waveguide

We experimentally demonstrate a new optical filter design based on a vertically coupled photonic crystal (PhC) cavity and a bus waveguide monolithically integrated on the silicon-on-insulator platform. The use of a vertically coupled waveguide gives flexibility in the choice of the waveguide material and dimensions, dramatically lowering the insertion loss while achieving very high coupling efficiencies to wavelength scale resonators and thus allows the creation of PhC-based optical filters with very high extinction ratio (>10 dB).Publisher PDFPeer reviewe

Integrated polymer microprisms for free space optical beam deflecting

We demonstrate beam deflection and multiple channel communication in free space optical communications using microprisms integrated directly onto an array of vertical cavity surface emitting lasers (VCSELs). The design and fabrication of such a transmitter is presented, and shown to achieve beam deflection of up to 10 in a planar configuration. A location discovery application, for use within a distributed network, is put forward and analysed. (c) 2009 Optical Society of AmericaPublisher PDFPeer reviewe

Electrically injected photonic-crystal nanocavities

Nano-emitters are the new generation of laser devices. A photonic-crystal cavity, which highly confines light in small volumes, in combination with quantum-dots can enhance the efficiency and lower the threshold of this device. The practical realisation of a reliable, electrically pumped photonic-crystal laser at room-temperature is, however, challenging. In this project, a design for such a laser was established. Its properties are split up into electrical, optical and thermal tasks that are individually investigated via various device simulations. The resulting device performance showed that with our design the quantum-dots can be pumped in order to provide gain and to overcome the loss of the system. Threshold currents can be as low as 10’s of μA and Q-factors in the range of 1000’s. Gallium arsenide wafers were grown according to our specifications and their diode behaviour confirmed. Photonic-crystal cavities were fabricated through a newly developed process based on a TiOₓ hard-mask. Beside membraned cavities, also cavities on oxidised AlGaAs were fabricated with help to a unique hard-mask removal method. The cavities were measured with a self-made micro-photoluminescence setup with the highest Q-factor of 4000 for the membrane cavity and a remarkable 2200 for the oxide cavity. The fabrication steps, regarding the electrically pumped photonic-crystal laser, were developed and it was shown that this device can be fabricated. During this project, a novel type of gentle confinement cavity was developed, based on the adaption of the dispersion curve (DA cavity) of a photonic-crystal waveguide. Q-factors of as high as 600.000 were measured for these cavities made in Silicon.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Integrated polymer microprisms for free space optical beam deflecting

We demonstrate beam deflection and multiple channel communication in free space optical communications using microprisms integrated directly onto an array of vertical cavity surface emitting lasers (VCSELs). The design and fabrication of such a transmitter is presented, and shown to achieve beam deflection of up to 10 in a planar configuration. A location discovery application, for use within a distributed network, is put forward and analysed. (c) 2009 Optical Society of America</p

Novel Photonic Crystal Nanocavity Design with high Tolerance to Disorder

We propose and experimentally demonstrate a new approach to the design of Photonic Crystal cavities. Rather than simply maximizing the design Q-factor, we take the effects of disorder into account, and develop a design that provides superior Q factors in the presence of disorder relative to existing designs.</p

Novel Photonic Crystal Nanocavity Design with high Tolerance to Disorder

We propose and experimentally demonstrate a new approach to the design of Photonic Crystal cavities. Rather than simply maximizing the design Q-factor, we take the effects of disorder into account, and develop a design that provides superior Q factors in the presence of disorder relative to existing designs.</p

Novel Dispersion-Adapted Photonic Crystal Cavity With Improved Disorder Stability

We present a photonic crystal cavity (PhCC) design methodology that is based on systematically engineering the dispersion curve of a PhC line-defect. Our combined numerical and analytical approach offers the option of using a variety of different defect modifications to create a gentle-confinement cavity with a Gaussian profile. Here, we demonstrate the principle of the method by employing relatively large hole-shifts (tens of nanometers), aiming for improved stability against disorder. Such improved stability compared with the established hetero-structure design approach is then experimentally confirmed on cavities fabricated in silicon. We point out some design features that are linked to this improved disorder stability. In addition, we note that different types of cavities exhibit dissimilar fabrication-limited Q-factors despite identical fabrication process

Highly efficient optical filter based on vertically coupled photonic crystal cavity and bus waveguide

We experimentally demonstrate a new optical filter design based on a vertically coupled photonic crystal (PhC) cavity and a bus waveguide monolithically integrated on the silicon-on-insulator platform. The use of a vertically coupled waveguide gives flexibility in the choice of the waveguide material and dimensions, dramatically lowering the insertion loss while achieving very high coupling efficiencies to wavelength scale resonators and thus allows the creation of PhC-based optical filters with very high extinction ratio (&gt;10 dB).</p