Query: Novel design for highpower single-lateral-mode lasers

Candidate papers:

abstract: Summary form only given. Today's rising power requirement for semiconductor lasers has created much interest in the research of high power single lateral mode lasers. Single lateral mode lasers are generally narrow in width in order to cut off propagation of higher order modes. Several problems arise from the narrow geometry such as catastrophic optical mirror damage (COMD) a large diffraction angle, and limited power due to the small gain volume. Recently, flared waveguides have been studied for increased gain volume and increased spot size on the front facet. The larger gain volume increases the peak output power of the diode. The increased spot size will raise the COMD power level by lowering the power density at the facet. The increased spot size will also decrease the diffraction angle. A problem with flaring the waveguide is that as the waveguide increases in width, it can support propagation of higher order modes. Our design addresses this by utilizing selective area epitaxy (SAE) to create a ridge that gets thinner as its width increases. The result is a flared ridge that is tapered along the length of the laser.
author_names: Anne E Huber

T S Yeoh

Reuel B Swint

C Y Woo

K E Lee

Sungwon David Roh

J J Coleman

Brian O Faircloth

M S Zediker
title: Novel design for high power single lateral mode lasers
venue: CLEO 2001
year: 2001

abstract: A new laser design for single mode high power applications is reported. The waveguide is a laterally flaring and transversely tapering GaAs buried ridge fabricated by selective area epitaxy. Single lateral mode powers of 200 mW were achieved.
author_names: Anne E Huber

T S Yeoh

Reuel B Swint

C Y Woo

Kenneth Eng-Kian Lee

Sungwon David Roh

J J Coleman

Brian O Faircloth

M S Zediker
title: Novel design for high power single lateral mode lasers
venue: IEEE Photonics Technology Letters
year: 2001

abstract: Slightly flared lasers are investigated in order to minimize the longitudinal spatial hole burning impact on the output power saturation of 1480 nm pump lasers. In such a device, the stripe width is narrow at the rear facet for strong single lateral mode operation whereas at the front facet the stripe widens in order to reduce the photon density and as a consequence decrease gain saturation through hole burning effect. We proposed a slightly flared lasers design in order to maintain a uniform photon density along the active stripe. Experimentally, this novel structure exhibits single transverse mode operation and a 30% output power improvement is obtained compared to the straight active waveguide.
author_names: Ali Guermache

Vincent Voiriot

R M Capella

Philippe Gallion

Joel Jacquet
title: New design rules and experimental study of slightly flared 1480 nm pump lasers
venue: IEEE Photonics Technology Letters
year: 2006

abstract: In this work, we present a novel and practical method for generating optical vortices in highpower laser systems. Off axis spiral phase mirrors are used at oblique angles of incidence in the beam path after amplification and compression allowing for the generation of high power optical vortices in almost any laser system. An off axis configuration is possible via modification of the azimuthal gradient of the spiral phase helix and is demonstrated with a simple model using a discrete spiral staircase. This work presents the design, fabrication, and implementation of off axis spiral phase mirrors in both low and high power laser systems. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
author_names: H -

K M
title: Off Axis Spiral Phase Mirrors for Generating High Intensity Optical Vortices
year: 2020

abstract: The `Laser hybrid Accelerator for Radiobiological Applications' LhARA, is conceived as a novel, uniquely flexible facility dedicated to the study of radiobiology. The technologies demonstrated in LhARA, which have wide application, will be developed to allow particle beam therapy to be delivered in a completely new regime, combining a variety of ion species in a single treatment fraction and exploiting ultra high dose rates. LhARA will be a hybrid accelerator system in which laser interactions drive the creation of a large flux of protons or light ions that are captured using a plasma (Gabor) lens and formed into a beam. The laser driven source allows protons and ions to be captured at energies significantly above those that pertain in conventional facilities, thus evading the current space charge limit on the instantaneous dose rate that can be delivered. The laser hybrid approach, therefore, will allow the vast `terra incognita' of the radiobiology that determines the response of tissue to ionising radiation to be studied with protons and light ions using a wide variety of time structures, spectral distributions, and spatial configurations at instantaneous dose rates up to and significantly beyond the ultra high dose rate `FLASH' regime. It is proposed that LhARA be developed in two stages. In the first stage, a programme of in vitro radiobiology will be served with proton beams with energies between 10MeV and 15MeV. In stage two, the beam will be accelerated using a fixed field accelerator (FFA) This will allow experiments to be carried out in vitro and in vivo with proton beam energies of up to 127MeV. In addition, ion beams with energies up to 33.4MeV per nucleon will be available for in vitro and in vivo experiments. This paper presents the conceptual design for LhARA and the R&D programme by which the LhARA consortium seeks to establish the facility.
author_names: Galen Aymar

T Becker

Stewart Boogert

Marco Borghesi

Robert Bingham

Ceri M Brenner

Philip Nicholas Burrows

Titus-Stefan Dascalu

Oliver C Ettlinger

Stephen Gibson

Tim Greenshaw

S Gruber

Dorothy M Gujral

Claire Hardiman

Jonathan R Hughes

W G Jones

Karen J Reeson Kirkby

Ajit Kurup

Jean-Baptiste Lagrange

Kenneth Richard Long

W Luk

J P Matheson

Paul McKenna

Ruth Mclauchlan

Z Najmudin

H T Lau

Jason L Parsons

Jaroslaw Pasternak

Jurgen Pozimski

Kevin M Prise

Monika Puchalska

Peter Ratoff

Giuseppe Schettino

W Shields

S L Smith

J W G Thomason

S Towe

Peter Weightman

Colin G Whyte

Rutherford Appleton Laboratory

Harwell Oxford

OX11 0QX

Maxeler Technologies Limited

3 Hammersmith Grove

London W6 0ND

John Adams Institute

Royal Holloway

University of London

TW20 0EX

Queen's University of Belfast

University Road

BT7 1NN

Northern Ireland

Department of Engineering Physics

University of Strathclyde

16 Richmond Street

G1 1XQ

University of Oxford

Denys Wilkinson Building

Keble Road

Oxford OX1 3RH

Imperial College London

Exhibition Road

SW7 2AZ

University of Liverpool

Liverpool L3 9TA

Christian Doppler Laboratory for Medical Radiation Research Oncology

Medical University of Vienna

23 Spitalgasse

1020 Vienna

Imperial College Nhs Healthcare Trust

The Bays

South Road

St Mary's Hospital

London W2 1NY

University of Manchester

Oxford Road

M13 9PL

Technische Universitat Wien

2 Stadionallee

Cockcroft Institute

Daresbury Laboratory

Sci-Tech Daresbury

WA4 4AD

National Physical Laboratory

Hampton Road

TW11 0LW

Stfc Daresbury Laboratory

Leo Care

Windmill Hill

East Sussex

BN27 4RY

Corerain Technologies

Changfu Jinmao Building

Trade-free Zone

Futian District

University of Surrey

388 Stag Hill

GU2 7XH

Imperial Patient

Public Involvement Group

The Clatterbridge Cancer Centre

CH63 4JY
title: The Laser hybrid Accelerator for Radiobiological Applications.
year: 2020

abstract: This thesis introduces three different novel conceptual approaches to development of high power, high brightness semiconductor lasers and is composed of three parts. The first part deals with the vertical concept of photonic band crystal (PBC) lasers. An ultra broad vertical waveguide structure composed of multiple epitaxial layers with different index of refraction exclusively supports the fundamental mode while all higher order modes are effectively suppressed. Since the field diameter is large, the maximum output power is high and the far field divergence is very narrow. Multi mode lasers emitting at 850 nm show a vertical divergence of only 7* while the maximum pulsed output power is as high as 20 W. The corresponding brightness is 300 MWcm 2sr 1, presenting an ultra high value in the 850 nm range. Devices with lateral single mode operation emitting at 980 nm exhibit a lateral divergence of 5* and a corresponding vertical divergence of 6* Their maximum continuous wave output power exceeds 2 W, limited by thermal effects. In pulsed operation the maximum output power and brightness are increased to 3.5 W and 87 MWcm 2sr 1 respectively. Even higher output powers are achieved for devices operating in gain switching mode. 100 ps wide optical pulses with peak output power of 10.7 W are emitted. Superior brightness values of 400 MWcm 2sr 1 and a pulse energy of 3 nJ are achieved. The highest degree of development is reached with PBC lasers emitting at 1060 nm. For the first time, the internal optical losses are reduced from 3.6 cm 1 to 1.3 cm 1 which leads to a significant enhancement in output power in continuous wave operation mode. The output power of 100 mm broad area devices increases from 3.9 W to 9.5 W. Single mode ridge waveguide lasers with a width of 9 mm and a length of 2.64 mm show a very high output power of 2.4 W and a lateral divergence of 4* and 6* in vertical direction respectively. Beam quality measurements revealed excellent M2 values of less than 2 up to an output power of 1.6 W. A record high brightness of 72 MWcm 2sr 1 is deduced. Quantum dots are employed as active material of PBC lasers for the first time, enabling outstanding properties of PBC lasers, like lower threshold currents and lower internal optical losses. In pulsed mode 100 mm broad and 1 mm long quantum dot based PBC lasers with not yet passivated facets, generate a much higher output power of 17.7 W compared to 8.8 W provided by quantum well based PBC lasers. Both maximum output powers are limited by sudden irreversible breakdown. Facets of PBC lasers with quantum dots indicate a lower susceptibility to degradation. An alternative approach to generation of high power and high brightness laser emission is investigated in the second part of this thesis. A vertical waveguide design based on the leaky wave laser concept is used to emit 30* tilted lobes with ultra narrow vertical beam divergence. Optimized tilted wave lasers (TWL) show a single dominating emission lobe with an extremely low diver
author_names: Kristijan Posilovic
title: Neuartige Wellenleiterkonzepte fur brillante Halbleiterlaser
year: 2015

abstract: Diffractive and micro optics have had fast growth in the last 20 years since microlithography technology began to be used for fabrication of optical elements. Nowadays, micro and diffractive optical element ~DOE! fabrication has reached a certain maturity. A wide range of applications has been developed. New applications and new integrated diffractive optical systems continue to emerge. The 22 papers from 16 countries published in this special section on diffractive optics reflect the recent trends and progress in DOE applications, fabrications, optical system design and implementations, and subwavelength structures. Both of us have witnessed and contributed to the progress of diffractive optics technology and have been co chairing SPIE conferences on diffractive optics at Photonics Asia and the SPIE Annual Meeting, respectively. It is a real pleasure for us to jointly edit the first special section on diffractive optics inOptical Engineering. The recent advances in nanoscale lithography and holography techniques provide a huge potential to create new subwavelength structures that efficiently manipulate light through diffraction and propagation. We believe that the new nanofabrication technologies will once again push diffractive optics and its natural extensions, including subwavelength structures, photonic crystals, near field optics and surface plasmon polariton optics, etc. to a new fast advance path. The impact will be even more important than what has happened in the last 20 years by the application of microlithography to fabrication of DOEs. In this special section on diffractive optics, new DOE applications include surface plasmon resonance sensors, ultrashort pulse processing, solar energy systems, interferometric testing, high power laser beam shaping, dynamic lenses, fiber Bragg grating fabrication, 3 D chipscale optical interconnections, and Talbot array illumination. Pedersen et al. design and imprint near field surface relief diffractive gratings for beam deflection and focusing in an injection moulded polymer chip for the new integrated surface plasmon resonance sensor, which is lowcost, compact, and robust with high performance. Lohokare et al. develop a novel conductive polymer based flip chip integration process for packaging arrayed VCSELs and microlenses, and demonstrate a 3 D chip scale optical interconnection system. Grunwald et al. present the spatiotemporal processing of an ultrashort pulse laser beam by exploiting specific advantages of thin film micro optical arrays. Gombert et al. address the design and the whole experimental process for the fabrication of surface relief microstructures on large areas that are useful in solar energy systems for antireflective surfaces, displays, light trapping in polymer solar cells, and facade protection from sun radiation. Pruss et al. apply computer generated holograms, which are able to generate several aspheric wave fronts, in interferometer metrology. The system is used for absolute testing of aspheric surfaces and diffractive transmission spheres. For highpower laser beam shaping applications, Liu et al. develop a modified iterative Fourier transform design algorithm. They design the beam shaping DOE and the DOE that combines beam conditioning and fan out functions for coupling the beam into multimode optical fibers. Ripoll t al. present a review and compare some useful iterative Fourier transform algorithms for the design of continuous and multiphase level DOEs for beam shaping. In the next three papers, Fresnel near field diffraction is studied for new applications. Onural discusses mathematical properties of the sampled quadratic phase function ~chirp! mainly that the Fourier transform of a sampled chirp function is also a sampled chirp function. The results are used in computer simulation of digital Special Section Guest Editorial
author_names: Yunlong Sheng
title: Diffractive Optics
year: 2019

abstract: Recently, there has been growing interest in photonic crystal surface emitting lasers (PC SELs) (1 4) The lasing principle exploited by the lasers is based on the band edge effect in a two dimensional (2D) PC, where the group velocity of light becomes zero and a 2D cavity mode is formed. The output power is coupled to the vertical direction by the PC itself, which gives rise to the surface emitting function. Based upon this novel lasing mechanism, PC SELs possess the following important features: first, perfect, single longitudinal, and lateral mode oscillation can be achieved even when the lasing area becomes very large (for example, devices >300 um in diameter) (1, 2, 4) and second, the polarization mode (2) and the beam pattern (4) can be controlled by appropriate design of the unit cell and/or lattice phase in the 2D PC (as a result, a range of vector beams (5, 6) can be directly generated) third, the on chip controllability of the beam direction (7) can be realized using a composite photonic crystal composed of square and rectangular lattices. In this report, we will overview the lasing principle, the device structures and these important features of PC SELs. The lasing oscillation in blue violet regime based on GaN PC SELs (8) will also be discussed.
author_names: Kyosuke Sakai

Susumu Noda
title: Photonic crystal surface emitting laser
venue: 22nd IEEE International Semiconductor Laser Conference
year: 2010

abstract: Recently, there has been growing interest in photonic crystal surface emitting lasers (PC SELs) (1 4) The lasing principle exploited by the lasers is based on the band edge effect in a two dimensional (2D) PC, where the group velocity of light becomes zero and a 2D cavity mode is formed. The output power is coupled to the vertical direction by the PC itself, which gives rise to the surface emitting function. Based upon this novel lasing mechanism, PC SELs possess the following important features: first, perfect, single longitudinal, and lateral mode oscillation can be achieved even when the lasing area becomes very large (for example, devices >300 um in diameter) (1, 2, 4) and second, the polarization mode (2) and the beam pattern (4) can be controlled by appropriate design of the unit cell and/or lattice phase in the 2D PC (as a result, a range of vector beams (5, 6) can be directly generated) third, the on chip controllability of the beam direction (7) can be realized using a composite photonic crystal composed of square and rectangular lattices. In this report, we will overview the lasing principle, the device structures and these important features of PC SELs. The lasing oscillation in blue violet regime based on GaN PC SELs (8) will also be discussed.
author_names: Kyosuke Sakai

Susumu Noda
title: Photonic crystal surface emitting laser
year: 2010

abstract: Semiconductor lasers offer significant operational advantages due to their high efficiency, compactness, and flexibility of pulse repetition rates. Their major drawback which limits quite severely the scope of their applicability is the relatively low emission power put out by a single semiconductor laser. To overcome this drawback, we propose a compact, high efficiency, highpower light source based on a synchronized broad area laser array. A variety of techniques have been proposed to synchronize laser arrays and coherently combine beams from separate lasers [1 10] They involve primarily optical engineering efforts such as MOPA injection locking, evanescent coupling, the use of Talbot cavities, and spectral beam combining. In some instances, optical engineering techniques have indeed produced phase locking in arrays of lasers (mostly, using low to moderate power lasers) However, these techniques are not easily scalable. The fundamental difficulty in realizing a scalable design is the complexity of the underlying dynamics. Indeed, lasers are inherently highly nonlinear systems that are capable of producing varieties of complex behaviors that depend quite sensitively on parameter values and initial conditions. One possible consequence of nonlinearity in lasers is that synchronization techniques that are suitable for low power, single mode lasers may not be applicable to high power, single or multimode lasers, because of the possibility of chaotic behavior that high power lasers usually display. Therefore, thorough understanding of this complex behavior is essential for the design of stable, scalable, and robust high power sources. We designed a novel scalable setup and technique to synchronize high power both CW and pulsed semiconductor laser arrays. Our design combines the major important features necessary to synchronize a nonlinear, possibly chaotic, dynamical system, namely: (a) injection locking and/or reflection from the gratings as a mechanism of mode locking and (b) laser coupling to induce the collective dynamics in the array. We have experimentally demonstrated several designs of synchronization broad area semiconductor laser arrays using commercially available high power laser arrays. The key advances of our synchronization experiments include:
author_names: Yehuda Braiman

Yaohua Liu

Vassili A Kireev

Vladimir A Protopopescu

Jacob Barhen
title: Synchronization of Arrays of High Power Lasers
year: 2003