Ian Elder | Selex ES (original) (raw)
Papers by Ian Elder
Technologies for Optical Countermeasures V, 2008
We describe the development of a time dependent thulium laser model. The model is used to predict... more We describe the development of a time dependent thulium laser model. The model is used to predict both the CW and temporal behaviour of a Tm:YAG laser. Experimental results from a diode-pumped Tm:YAG laser are obtained and the model is used to obtain good agreement with these observations for both the CW and temporal behaviour of the laser. Particular results relate to switch-on time delays and the effect of pump diode modulation on Tm laser efficiency. The laser model has been extended to the case of the Ho:YAG laser where other important effects due to ground state depletion and self re-absorption must be taken into account. The holmium laser model has recently been used to predict reported experimental results from a thulium fibre laser pumped Ho:YAG laser.
Technologies for Optical Countermeasures IX, 2012
We investigate the use of volume Bragg gratings (VBGs) to achieve single longitudinal mode operat... more We investigate the use of volume Bragg gratings (VBGs) to achieve single longitudinal mode operation in a simple 3 mirror, diode pumped Nd:YVO4 Laser cavity at both 1064nm and 1342nm. A double VBG configuration is constructed and shown to achieve single longitudinal mode operation with output powers of 2.3W and 2W at 1342nm and 1064nm respectively, the spectral performance of the dual VBG setup is also analyzed. In another configuration, we investigate the use of VBGs as wavelength selective elements in a dual-wavelength laser. Using this method we were able to achieve a combined output power of 3.55W at 1342 and 1064nm emission simultaneously, with a conversion efficiency of 18%.
Technologies for Optical Countermeasures IX, 2012
ABSTRACT A simple scheme for efficient generation of two micron laser radiation is reported. Usin... more ABSTRACT A simple scheme for efficient generation of two micron laser radiation is reported. Using a thulium fibre laser to pump a Q-switched Ho:YAG laser 31.7 W of average output power is achieved with an M2 of 1.5 (an optical-to-optical conversion efficiency of 67% in terms of absorbed pump power) at a wavelength of 2.1 μm. A single-pass pump geometry is used, eliminating the risk of feedback of unabsorbed light into the fibre laser.
Applied Optics, 1997
Room-temperature operation of a continuous-wave Tm:YAP laser is reported. A 3 W laser diode in an... more Room-temperature operation of a continuous-wave Tm:YAP laser is reported. A 3 W laser diode in an end-pumped geometry is used to generate 730 mW of thulium laser output, which represents a conversion efficiency of 42% in terms of absorbed pump power. The laser operates on a number of lines in the wavelength range 1.965 to 2.020 m.
Emerging Imaging and Sensing Technologies, 2016
Laser-based Micro- and Nanoprocessing X, 2016
Optics Communications, 1998
A comparison of the room-temperature operation of continuous wave Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF... more A comparison of the room-temperature operation of continuous wave Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF lasers is reported. A conversion efficiency from absorbed pump power to laser output of 42% was demonstrated in Tm:YAP, compared to 14% in Tm,Ho:YAP and 30% in Tm,Ho:YLF. Tm:YAP was observed to operate multiline in the range 1.965 to 2.020 mm, whereas the holmium lasers operated on a single transition. The markedly different temporal behaviour of the single and double-doped crystals is analysed and discussed. q 1998 Elsevier Science B.V.
Optics Communications, 1998
ABSTRACT A comparison of the room-temperature operation of diode-pumped continuous-wave thulium-d... more ABSTRACT A comparison of the room-temperature operation of diode-pumped continuous-wave thulium-doped YAP and YAG lasers is reported. A markedly superior conversion efficiency using 4.2% doped Tm:YAP was measured, 730 mW of laser output being generated with a 3 W pump diode, representing a 42% conversion of absorbed diode light to laser output. With 6% Tm:YAG, laser output was restricted to 270 mW, a 21% conversion efficiency. Both lasers were found to generate diffraction-limited output. Greater upconversion losses in YAG than YAP are proposed as a factor contributing to its poorer laser performance.
Technologies for Optical Countermeasures IX, 2012
We describe a beam combiner based on a cascade of dichroic components implemented in a hollow wav... more We describe a beam combiner based on a cascade of dichroic components implemented in a hollow waveguide integrated optic format. The approach results in a compact, rugged, optically robust solution for providing simultaneous multi-wavelength emission in the near and mid-IR atmospheric transmission windows. In the approach the individual dichroic beam combiner components are held in precision alignment slots in the hollow waveguide circuit and the different input wavelengths are guided between the components to a common output port. The hollow waveguide circuit and the alignment slots for the components are formed in the surface of a Macor (machinable glass-ceramic) substrate using precision CNC machining techniques. The hollow waveguides have fundamentally different propagation characteristics to solid core waveguides leading to transmission characteristics close to those of the atmosphere while still providing useful light guidance properties. Because of the hollow nature of the core, the transmission efficiency and power handling of the hollow waveguide circuit can be designed to be very high across a broad waveband range. The specifications for the dichroic beam combiners and the design of the hollow waveguide circuit are described in relation to a beam combiner for combining three QCLs emitting at 3.95 μm, 4.05 μm and 4.6 μm and a Ho:YAG laser emitting at 2.1 µm. Details of the design, modeling and manufacturing work, and preliminary assessments of the associated components, are described. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8543 854306-2 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8543 854306-7 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8543 854306-10 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms
Acquisition, Tracking, Pointing, and Laser Systems Technologies XXIII, 2009
Deformable bimorph mirrors with high damage threshold dielectric coatings are demonstrated as bot... more Deformable bimorph mirrors with high damage threshold dielectric coatings are demonstrated as both intra-and extracavity components with a pulsed energy diode-pumped Nd:YAG zigzag slab laser operating at the 150 mJ level. Two resonator configurations were tested for intra-cavity operation; with a plane-plane resonator the far-field brightness was enhanced by up to a factor of 1.5, whilst with a cross-Porro resonator an enhancement of up to 2.2 was achieved. As an extracavity component far-field beam steering of ±2 mrad was demonstrated. Downloaded from SPIE Digital Library on 15 Jul 2010 to 20.133.0.8. Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 7338 733805-2 Downloaded from SPIE Digital Library on 15 Jul 2010 to 20.133.0.8. Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 7338 733805-9 Downloaded from SPIE Digital Library on 15 Jul 2010 to 20.133.0.8. Terms of Use: http://spiedl.org/terms View publication stats View publication stats
Technologies for Optical Countermeasures III, 2006
A laser diode end-pumped Q-switched Nd:YVO4 laser operating over a 25% to 100% duty cycle range h... more A laser diode end-pumped Q-switched Nd:YVO4 laser operating over a 25% to 100% duty cycle range has been built and characterised. A maximum average output power of 24.5 W has been achieved at an optical-to-optical conversion efficiency of 43%, with a beam quality factor M2 of 1.1.
Electro-Optical and Infrared Systems: Technology and Applications IX, 2012
Results are presented for generation of 1064 nm and 1573 nm outputs using a common ring resonator... more Results are presented for generation of 1064 nm and 1573 nm outputs using a common ring resonator for a laser diodeside-pumped zig-zag geometry Nd:YAG laser slab and three NCPM (non-critically phase-matched) KTP crystals. The performance of the resonator at each wavelength is reported, for various configurations. First a common resonator was tested, then a separate resonator was used to gain an understanding of the performance variation with resonator length and OPO output coupling. A second common resonator was then tested, which had an optimized configuration to improve its efficiency. The conversion efficiency of the final design was 35% with 29 mJ output at 1573 nm wavelength for 83 mJ at 1064 nm.
Technologies for Optical Countermeasures VI, 2009
ABSTRACT Results are presented for generation of visible and mid-IR output using a common fibre-b... more ABSTRACT Results are presented for generation of visible and mid-IR output using a common fibre-based laser pump source. This source comprised a master oscillator power amplifier (MOPA) configuration incorporating a semiconductor seed source. Operation in the nanosecond and picosecond range is possible via use of the appropriate seed source. The MOPA is capable of generating 100 W average power in an output beam with an M2 of 1.1. Here the MOPA was operated in the nanosecond regime, using 100 ns seed pulses at a pulse repetition frequency of 100 kHz. 40 W each of pump power was available for a frequency doubling and an OPO stage. 9.8 W of green light was generated in an output beam with an M2 of 1.2; using a degenerate PPLN OPO 12.7 W of broadband mid-IR output, with a FWHM linewidth in excess of 170 nm, was generated.
Laser Technology for Defense and Security V, 2009
A simple scheme for efficient generation of mid-IR laser radiation is reported. Using a 50 W thul... more A simple scheme for efficient generation of mid-IR laser radiation is reported. Using a 50 W thulium fibre laser to pump a Q-switched Ho:YAG laser 27.3 W of average output power is achieved with an M 2 of 1.5 (optical to optical conversion efficiency 65%) at a wavelength of 2.1 µm. The holmium laser is used to pump a ZGP OPO generating 12.6 W of average output power in the 3-5 μm waveband (optical to optical conversion efficiency 52%) with a worst case M 2 of 2.7. These efficiencies were maintained at 25% and 50% duty cycle operation.
Advanced Solid State Lasers, 1995
Characterization of a CW Diode-Pumped Tm:YAlO, Laser IF Elder and MJP Payne Defence Research Agen... more Characterization of a CW Diode-Pumped Tm:YAlO, Laser IF Elder and MJP Payne Defence Research Agency, St. Andrews R oa Malvern, Worcs WR14 3PS. Unitéd Kingabm Abstract We report on a rmm temperature cw Tm:YA103 laser end-pumped by a single 3 W laser diode. ...
Advanced Solid State Lasers, 1996
Tele +44 (0)1684 896139 Fax +44(0)1684 896270 E-Mail elder@dra .hmg .g b Abstract
Electronics Letters, 1998
Applied Physics Letters, 2013
Conversion efficiencies of 44% and 56% are demonstrated in single and double-pass pump geometries... more Conversion efficiencies of 44% and 56% are demonstrated in single and double-pass pump geometries respectively for a degenerate 1 micron pumped PPLN OPO. Pump feedback in the double-pass geometry acts as a pulse shortening mechanism.
Technologies for Optical Countermeasures V, 2008
We describe the development of a time dependent thulium laser model. The model is used to predict... more We describe the development of a time dependent thulium laser model. The model is used to predict both the CW and temporal behaviour of a Tm:YAG laser. Experimental results from a diode-pumped Tm:YAG laser are obtained and the model is used to obtain good agreement with these observations for both the CW and temporal behaviour of the laser. Particular results relate to switch-on time delays and the effect of pump diode modulation on Tm laser efficiency. The laser model has been extended to the case of the Ho:YAG laser where other important effects due to ground state depletion and self re-absorption must be taken into account. The holmium laser model has recently been used to predict reported experimental results from a thulium fibre laser pumped Ho:YAG laser.
Technologies for Optical Countermeasures IX, 2012
We investigate the use of volume Bragg gratings (VBGs) to achieve single longitudinal mode operat... more We investigate the use of volume Bragg gratings (VBGs) to achieve single longitudinal mode operation in a simple 3 mirror, diode pumped Nd:YVO4 Laser cavity at both 1064nm and 1342nm. A double VBG configuration is constructed and shown to achieve single longitudinal mode operation with output powers of 2.3W and 2W at 1342nm and 1064nm respectively, the spectral performance of the dual VBG setup is also analyzed. In another configuration, we investigate the use of VBGs as wavelength selective elements in a dual-wavelength laser. Using this method we were able to achieve a combined output power of 3.55W at 1342 and 1064nm emission simultaneously, with a conversion efficiency of 18%.
Technologies for Optical Countermeasures IX, 2012
ABSTRACT A simple scheme for efficient generation of two micron laser radiation is reported. Usin... more ABSTRACT A simple scheme for efficient generation of two micron laser radiation is reported. Using a thulium fibre laser to pump a Q-switched Ho:YAG laser 31.7 W of average output power is achieved with an M2 of 1.5 (an optical-to-optical conversion efficiency of 67% in terms of absorbed pump power) at a wavelength of 2.1 μm. A single-pass pump geometry is used, eliminating the risk of feedback of unabsorbed light into the fibre laser.
Applied Optics, 1997
Room-temperature operation of a continuous-wave Tm:YAP laser is reported. A 3 W laser diode in an... more Room-temperature operation of a continuous-wave Tm:YAP laser is reported. A 3 W laser diode in an end-pumped geometry is used to generate 730 mW of thulium laser output, which represents a conversion efficiency of 42% in terms of absorbed pump power. The laser operates on a number of lines in the wavelength range 1.965 to 2.020 m.
Emerging Imaging and Sensing Technologies, 2016
Laser-based Micro- and Nanoprocessing X, 2016
Optics Communications, 1998
A comparison of the room-temperature operation of continuous wave Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF... more A comparison of the room-temperature operation of continuous wave Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF lasers is reported. A conversion efficiency from absorbed pump power to laser output of 42% was demonstrated in Tm:YAP, compared to 14% in Tm,Ho:YAP and 30% in Tm,Ho:YLF. Tm:YAP was observed to operate multiline in the range 1.965 to 2.020 mm, whereas the holmium lasers operated on a single transition. The markedly different temporal behaviour of the single and double-doped crystals is analysed and discussed. q 1998 Elsevier Science B.V.
Optics Communications, 1998
ABSTRACT A comparison of the room-temperature operation of diode-pumped continuous-wave thulium-d... more ABSTRACT A comparison of the room-temperature operation of diode-pumped continuous-wave thulium-doped YAP and YAG lasers is reported. A markedly superior conversion efficiency using 4.2% doped Tm:YAP was measured, 730 mW of laser output being generated with a 3 W pump diode, representing a 42% conversion of absorbed diode light to laser output. With 6% Tm:YAG, laser output was restricted to 270 mW, a 21% conversion efficiency. Both lasers were found to generate diffraction-limited output. Greater upconversion losses in YAG than YAP are proposed as a factor contributing to its poorer laser performance.
Technologies for Optical Countermeasures IX, 2012
We describe a beam combiner based on a cascade of dichroic components implemented in a hollow wav... more We describe a beam combiner based on a cascade of dichroic components implemented in a hollow waveguide integrated optic format. The approach results in a compact, rugged, optically robust solution for providing simultaneous multi-wavelength emission in the near and mid-IR atmospheric transmission windows. In the approach the individual dichroic beam combiner components are held in precision alignment slots in the hollow waveguide circuit and the different input wavelengths are guided between the components to a common output port. The hollow waveguide circuit and the alignment slots for the components are formed in the surface of a Macor (machinable glass-ceramic) substrate using precision CNC machining techniques. The hollow waveguides have fundamentally different propagation characteristics to solid core waveguides leading to transmission characteristics close to those of the atmosphere while still providing useful light guidance properties. Because of the hollow nature of the core, the transmission efficiency and power handling of the hollow waveguide circuit can be designed to be very high across a broad waveband range. The specifications for the dichroic beam combiners and the design of the hollow waveguide circuit are described in relation to a beam combiner for combining three QCLs emitting at 3.95 μm, 4.05 μm and 4.6 μm and a Ho:YAG laser emitting at 2.1 µm. Details of the design, modeling and manufacturing work, and preliminary assessments of the associated components, are described. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8543 854306-2 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8543 854306-7 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8543 854306-10 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms
Acquisition, Tracking, Pointing, and Laser Systems Technologies XXIII, 2009
Deformable bimorph mirrors with high damage threshold dielectric coatings are demonstrated as bot... more Deformable bimorph mirrors with high damage threshold dielectric coatings are demonstrated as both intra-and extracavity components with a pulsed energy diode-pumped Nd:YAG zigzag slab laser operating at the 150 mJ level. Two resonator configurations were tested for intra-cavity operation; with a plane-plane resonator the far-field brightness was enhanced by up to a factor of 1.5, whilst with a cross-Porro resonator an enhancement of up to 2.2 was achieved. As an extracavity component far-field beam steering of ±2 mrad was demonstrated. Downloaded from SPIE Digital Library on 15 Jul 2010 to 20.133.0.8. Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 7338 733805-2 Downloaded from SPIE Digital Library on 15 Jul 2010 to 20.133.0.8. Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 7338 733805-9 Downloaded from SPIE Digital Library on 15 Jul 2010 to 20.133.0.8. Terms of Use: http://spiedl.org/terms View publication stats View publication stats
Technologies for Optical Countermeasures III, 2006
A laser diode end-pumped Q-switched Nd:YVO4 laser operating over a 25% to 100% duty cycle range h... more A laser diode end-pumped Q-switched Nd:YVO4 laser operating over a 25% to 100% duty cycle range has been built and characterised. A maximum average output power of 24.5 W has been achieved at an optical-to-optical conversion efficiency of 43%, with a beam quality factor M2 of 1.1.
Electro-Optical and Infrared Systems: Technology and Applications IX, 2012
Results are presented for generation of 1064 nm and 1573 nm outputs using a common ring resonator... more Results are presented for generation of 1064 nm and 1573 nm outputs using a common ring resonator for a laser diodeside-pumped zig-zag geometry Nd:YAG laser slab and three NCPM (non-critically phase-matched) KTP crystals. The performance of the resonator at each wavelength is reported, for various configurations. First a common resonator was tested, then a separate resonator was used to gain an understanding of the performance variation with resonator length and OPO output coupling. A second common resonator was then tested, which had an optimized configuration to improve its efficiency. The conversion efficiency of the final design was 35% with 29 mJ output at 1573 nm wavelength for 83 mJ at 1064 nm.
Technologies for Optical Countermeasures VI, 2009
ABSTRACT Results are presented for generation of visible and mid-IR output using a common fibre-b... more ABSTRACT Results are presented for generation of visible and mid-IR output using a common fibre-based laser pump source. This source comprised a master oscillator power amplifier (MOPA) configuration incorporating a semiconductor seed source. Operation in the nanosecond and picosecond range is possible via use of the appropriate seed source. The MOPA is capable of generating 100 W average power in an output beam with an M2 of 1.1. Here the MOPA was operated in the nanosecond regime, using 100 ns seed pulses at a pulse repetition frequency of 100 kHz. 40 W each of pump power was available for a frequency doubling and an OPO stage. 9.8 W of green light was generated in an output beam with an M2 of 1.2; using a degenerate PPLN OPO 12.7 W of broadband mid-IR output, with a FWHM linewidth in excess of 170 nm, was generated.
Laser Technology for Defense and Security V, 2009
A simple scheme for efficient generation of mid-IR laser radiation is reported. Using a 50 W thul... more A simple scheme for efficient generation of mid-IR laser radiation is reported. Using a 50 W thulium fibre laser to pump a Q-switched Ho:YAG laser 27.3 W of average output power is achieved with an M 2 of 1.5 (optical to optical conversion efficiency 65%) at a wavelength of 2.1 µm. The holmium laser is used to pump a ZGP OPO generating 12.6 W of average output power in the 3-5 μm waveband (optical to optical conversion efficiency 52%) with a worst case M 2 of 2.7. These efficiencies were maintained at 25% and 50% duty cycle operation.
Advanced Solid State Lasers, 1995
Characterization of a CW Diode-Pumped Tm:YAlO, Laser IF Elder and MJP Payne Defence Research Agen... more Characterization of a CW Diode-Pumped Tm:YAlO, Laser IF Elder and MJP Payne Defence Research Agency, St. Andrews R oa Malvern, Worcs WR14 3PS. Unitéd Kingabm Abstract We report on a rmm temperature cw Tm:YA103 laser end-pumped by a single 3 W laser diode. ...
Advanced Solid State Lasers, 1996
Tele +44 (0)1684 896139 Fax +44(0)1684 896270 E-Mail elder@dra .hmg .g b Abstract
Electronics Letters, 1998
Applied Physics Letters, 2013
Conversion efficiencies of 44% and 56% are demonstrated in single and double-pass pump geometries... more Conversion efficiencies of 44% and 56% are demonstrated in single and double-pass pump geometries respectively for a degenerate 1 micron pumped PPLN OPO. Pump feedback in the double-pass geometry acts as a pulse shortening mechanism.