The dependence of the Q-factor of the microfiber coil resonator on different input/output couplin... more The dependence of the Q-factor of the microfiber coil resonator on different input/output couplings is investigated and compared. A method of slowly varying input/output coupling is presented to considerably simplify the fabrication of high-Q resonators. The microfiber coil resonator (MCR) is a promising functional device for compact all-fiber circuits. I n particular, with the most recent developments in th e
37th European Conference and Exposition on Optical Communications, 2011
We report flat, broadband supercontinuum generation at low pump pulse energies (69pJ 740fs pulses... more We report flat, broadband supercontinuum generation at low pump pulse energies (69pJ 740fs pulses at 1540nm) in a lead-silicate fibre providing a unique combination of high nonlinearity (820W -1 km -1 ) and a flat near-zero dispersion profile.
(CLEO). Conference on Lasers and Electro-Optics, 2005., 2005
We present experimental and theoretical results on the linewidth of an Er-Yb doped DFB fiber lase... more We present experimental and theoretical results on the linewidth of an Er-Yb doped DFB fiber laser. Recently observed dependencies on pump configuration and power are explained by pump noise induced temperature fluctuations.
Solid State Laser Technologies and Femtosecond Phenomena, 2004
The anomalous linewidth behavior in a DFB fiber laser is investigated. It is shown that not only ... more The anomalous linewidth behavior in a DFB fiber laser is investigated. It is shown that not only does the linewidth deviate drastically from the Schawlow-Townes linewidth formula by increasing with pump and laser power, but it also varies significantly with the pumping configuration used. These results have potentially important implications for the design and operation of such fiber lasers.
Titanium (Ti)-in-diffused lithium niobate waveguide mode filters fabricated using laser-induced f... more Titanium (Ti)-in-diffused lithium niobate waveguide mode filters fabricated using laser-induced forward transfer followed by thermal diffusion are presented. The mode control was achieved by adjusting the separation between adjacent Ti segments thus varying the average value of the refractive index along the length of the in-diffused channel waveguides. The fabrication details, loss measurements and near-field optical characterization of the mode filters are presented. Modeling results regarding the device performance are also discussed.
Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2013, 2013
ABSTRACT We report experimental results on a dual suspended core nanomechanical optical fibre. Op... more ABSTRACT We report experimental results on a dual suspended core nanomechanical optical fibre. Optical switching of light from one core to another is achieved through moving one core by just 8 nm.
37th European Conference and Exposition on Optical Communications, 2011
We report the successful fabrication of a new type of dual core fiber, comprising 2 optical cores... more We report the successful fabrication of a new type of dual core fiber, comprising 2 optical cores suspended in air. The cores are sub-micron in size, each held in place by 2 thin glass membranes attached to the cladding. The successful realisation of this fiber should open up a range of interesting applications in a variety of different areas.
Workshop on Specialty Optical Fibers and their Applications, 2013
ABSTRACT We demonstrate using a sheet-stacking method to fabricate nanomechanical optical fibres ... more ABSTRACT We demonstrate using a sheet-stacking method to fabricate nanomechanical optical fibres with long and thin spokes. This approach shows great advantage for manufacturing complex multi-material speciality optical fibres with novel photonic and nanomechanical functionalities.
2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
ABSTRACT A nanomechanical optical fibre with a mechanically adjustable dual-core structure has be... more ABSTRACT A nanomechanical optical fibre with a mechanically adjustable dual-core structure has been demonstrated recently. The realisation of equivalent systems with an electric actuation would allow for low-loss all-fibre reconfigurable optical networks. Here, the feasibility of nanoelectromechanical actuation of the dual-core fibre is investigated. Such optical systems with mechanically adjustable or controllable components are well known in the form of silicon micro- and nanoelectromechanical systems (MEMS and NEMS) and are widely used in various optoelectronic devices, for example 2-D optical switches and reconfigurable optical add-drop multiplexers.
ABSTRACT We propose and demonstrate a new phase-sensitive (PS) scheme based on four-wave mixing f... more ABSTRACT We propose and demonstrate a new phase-sensitive (PS) scheme based on four-wave mixing followed by a polarizer to achieve an ideal binary step-like phase transfer function at nonlinear phase shifts as low as 0.3 rad by significantly increasing the parametric deamplification component. PS operation is obtained by polarization mixing the phase-locked and orthogonally polarized signal and idler, which is generated in a degenerate dual-pump vector parametric amplifier.
We present the design and fabrication of a tunable optical buffer device based on III-V semicondu... more We present the design and fabrication of a tunable optical buffer device based on III-V semiconductor platform for telecommunication applications. The device comprises two indium phosphide suspended parallel waveguides with cross sectional dimension of 200 nm by 300 nm, separated by an air gap. The gap between the waveguides was designed to be adjustable by electrostatic force. Our simulation estimated that only 3 V is required to increase the separation distance from 50 nm to 500 nm; this translates to a change in the propagation delay by a factor of 2. The first generation of the suspended waveguide structure for optical buffering was fabricated. The sample was grown on an InP substrate by molecular beam epitaxy. The waveguide pattern is written onto a 300 nm thick InP device layer by electron beam lithography and plasma etching. Electrodes were incorporated into the structure to apply voltages for MEMS actuation.
We investigate both theoretically and experimentally the properties of supercontinuum generation ... more We investigate both theoretically and experimentally the properties of supercontinuum generation in the nearinfrared and visible regimes using high-power picosecond pulses propagating in a photonic crystal optical fiber. We discuss the effect of the pump wavelength relative to the fiber zero-dispersion wavelength on the conversion efficiency of pump power to shorter wavelengths. Finally, we consider picosecond supercontinuum generation in the presence of a mode cutoff when the pump is launched into a higher order fiber mode.
Whispering gallery modes of a microdisk resonator are useful for the optical detection of single ... more Whispering gallery modes of a microdisk resonator are useful for the optical detection of single rubidium and cesium atoms near the surface of a substrate. Light is coupled into two high-Q whispering-gallery modes of the disk which can provide attractive and/or repulsive potentials, respectively, via their evanescent fields. The sum potential, including van der Waals/Casimir-Polder surface forces, may be tuned to exhibit a minimum at distances on the order of 100 nm from the disk surface. Simultaneously optically trapping and detecting is possible, with the back-action of an atom held in this trap on the light fields being sufficiently strong to provide a measurable effect. Atom trapping and detection depend on a variety of system parameters and experimental realizations differ for different atoms.
We review the use of a semiconductor optical amplifier for intensity noise reduction of incoheren... more We review the use of a semiconductor optical amplifier for intensity noise reduction of incoherent sources and describe our recent experimental and theoretical work in this area. We focus in particular on understanding the physical mechanisms underpinning the noise reduction process and which govern the associated spectral broadening. We also describe in detail how onward filtering and transmission degrade the noise reduction and impact use of the technique within a high density spectrum-sliced system.
The dependence of the Q-factor of the microfiber coil resonator on different input/output couplin... more The dependence of the Q-factor of the microfiber coil resonator on different input/output couplings is investigated and compared. A method of slowly varying input/output coupling is presented to considerably simplify the fabrication of high-Q resonators. The microfiber coil resonator (MCR) is a promising functional device for compact all-fiber circuits. I n particular, with the most recent developments in th e
37th European Conference and Exposition on Optical Communications, 2011
We report flat, broadband supercontinuum generation at low pump pulse energies (69pJ 740fs pulses... more We report flat, broadband supercontinuum generation at low pump pulse energies (69pJ 740fs pulses at 1540nm) in a lead-silicate fibre providing a unique combination of high nonlinearity (820W -1 km -1 ) and a flat near-zero dispersion profile.
(CLEO). Conference on Lasers and Electro-Optics, 2005., 2005
We present experimental and theoretical results on the linewidth of an Er-Yb doped DFB fiber lase... more We present experimental and theoretical results on the linewidth of an Er-Yb doped DFB fiber laser. Recently observed dependencies on pump configuration and power are explained by pump noise induced temperature fluctuations.
Solid State Laser Technologies and Femtosecond Phenomena, 2004
The anomalous linewidth behavior in a DFB fiber laser is investigated. It is shown that not only ... more The anomalous linewidth behavior in a DFB fiber laser is investigated. It is shown that not only does the linewidth deviate drastically from the Schawlow-Townes linewidth formula by increasing with pump and laser power, but it also varies significantly with the pumping configuration used. These results have potentially important implications for the design and operation of such fiber lasers.
Titanium (Ti)-in-diffused lithium niobate waveguide mode filters fabricated using laser-induced f... more Titanium (Ti)-in-diffused lithium niobate waveguide mode filters fabricated using laser-induced forward transfer followed by thermal diffusion are presented. The mode control was achieved by adjusting the separation between adjacent Ti segments thus varying the average value of the refractive index along the length of the in-diffused channel waveguides. The fabrication details, loss measurements and near-field optical characterization of the mode filters are presented. Modeling results regarding the device performance are also discussed.
Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2013, 2013
ABSTRACT We report experimental results on a dual suspended core nanomechanical optical fibre. Op... more ABSTRACT We report experimental results on a dual suspended core nanomechanical optical fibre. Optical switching of light from one core to another is achieved through moving one core by just 8 nm.
37th European Conference and Exposition on Optical Communications, 2011
We report the successful fabrication of a new type of dual core fiber, comprising 2 optical cores... more We report the successful fabrication of a new type of dual core fiber, comprising 2 optical cores suspended in air. The cores are sub-micron in size, each held in place by 2 thin glass membranes attached to the cladding. The successful realisation of this fiber should open up a range of interesting applications in a variety of different areas.
Workshop on Specialty Optical Fibers and their Applications, 2013
ABSTRACT We demonstrate using a sheet-stacking method to fabricate nanomechanical optical fibres ... more ABSTRACT We demonstrate using a sheet-stacking method to fabricate nanomechanical optical fibres with long and thin spokes. This approach shows great advantage for manufacturing complex multi-material speciality optical fibres with novel photonic and nanomechanical functionalities.
2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
ABSTRACT A nanomechanical optical fibre with a mechanically adjustable dual-core structure has be... more ABSTRACT A nanomechanical optical fibre with a mechanically adjustable dual-core structure has been demonstrated recently. The realisation of equivalent systems with an electric actuation would allow for low-loss all-fibre reconfigurable optical networks. Here, the feasibility of nanoelectromechanical actuation of the dual-core fibre is investigated. Such optical systems with mechanically adjustable or controllable components are well known in the form of silicon micro- and nanoelectromechanical systems (MEMS and NEMS) and are widely used in various optoelectronic devices, for example 2-D optical switches and reconfigurable optical add-drop multiplexers.
ABSTRACT We propose and demonstrate a new phase-sensitive (PS) scheme based on four-wave mixing f... more ABSTRACT We propose and demonstrate a new phase-sensitive (PS) scheme based on four-wave mixing followed by a polarizer to achieve an ideal binary step-like phase transfer function at nonlinear phase shifts as low as 0.3 rad by significantly increasing the parametric deamplification component. PS operation is obtained by polarization mixing the phase-locked and orthogonally polarized signal and idler, which is generated in a degenerate dual-pump vector parametric amplifier.
We present the design and fabrication of a tunable optical buffer device based on III-V semicondu... more We present the design and fabrication of a tunable optical buffer device based on III-V semiconductor platform for telecommunication applications. The device comprises two indium phosphide suspended parallel waveguides with cross sectional dimension of 200 nm by 300 nm, separated by an air gap. The gap between the waveguides was designed to be adjustable by electrostatic force. Our simulation estimated that only 3 V is required to increase the separation distance from 50 nm to 500 nm; this translates to a change in the propagation delay by a factor of 2. The first generation of the suspended waveguide structure for optical buffering was fabricated. The sample was grown on an InP substrate by molecular beam epitaxy. The waveguide pattern is written onto a 300 nm thick InP device layer by electron beam lithography and plasma etching. Electrodes were incorporated into the structure to apply voltages for MEMS actuation.
We investigate both theoretically and experimentally the properties of supercontinuum generation ... more We investigate both theoretically and experimentally the properties of supercontinuum generation in the nearinfrared and visible regimes using high-power picosecond pulses propagating in a photonic crystal optical fiber. We discuss the effect of the pump wavelength relative to the fiber zero-dispersion wavelength on the conversion efficiency of pump power to shorter wavelengths. Finally, we consider picosecond supercontinuum generation in the presence of a mode cutoff when the pump is launched into a higher order fiber mode.
Whispering gallery modes of a microdisk resonator are useful for the optical detection of single ... more Whispering gallery modes of a microdisk resonator are useful for the optical detection of single rubidium and cesium atoms near the surface of a substrate. Light is coupled into two high-Q whispering-gallery modes of the disk which can provide attractive and/or repulsive potentials, respectively, via their evanescent fields. The sum potential, including van der Waals/Casimir-Polder surface forces, may be tuned to exhibit a minimum at distances on the order of 100 nm from the disk surface. Simultaneously optically trapping and detecting is possible, with the back-action of an atom held in this trap on the light fields being sufficiently strong to provide a measurable effect. Atom trapping and detection depend on a variety of system parameters and experimental realizations differ for different atoms.
We review the use of a semiconductor optical amplifier for intensity noise reduction of incoheren... more We review the use of a semiconductor optical amplifier for intensity noise reduction of incoherent sources and describe our recent experimental and theoretical work in this area. We focus in particular on understanding the physical mechanisms underpinning the noise reduction process and which govern the associated spectral broadening. We also describe in detail how onward filtering and transmission degrade the noise reduction and impact use of the technique within a high density spectrum-sliced system.
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Papers by Peter Horak