Combination of Low-Index Quantum Barrier and Super Large Optical Cavity Designs for Ultranarrow Vertical Far-Fields From High-Power Broad-Area Lasers

Pietrzak, A.; Crump, P.; Wenzel, H.; Erbert, G.; Bugge, F.; Tränkle, G.

doi:10.1109/jstqe.2011.2109939

Cited by 57 publications

(23 citation statements)

References 17 publications

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“…We are pursuing two advanced waveguide concepts to achieve the best overall performance -the use of an optical trap (OT) to tailor the optical mode profiles [2,3] and lowindex quantum barriers (LIQB) to reduce the waveguiding by the MQW region [4]. Both approaches are based on InGaAs QW active regions for operation at ~ 975nm.…”

Section: Epitaxial Designmentioning

confidence: 99%

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Design Optimisation of High-Brightness Laser Diodes for External Cavity Operation in the BRIDLE Project

Larkins

Bull

Kaunga-Nyirenda

et al. 2014

2014 International Semiconductor Laser Conference

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Section: Epitaxial Designmentioning

confidence: 99%

“…The SBC lasers employ an Al0.15Ga0.85As waveguide and GaAs0.55P0.45 LIQB layers. As discussed in [4,5], by lowering the index of the MQW region, the LIQB layers facilitate a narrow FF divergence -at the cost of a small type II band offset with the waveguide layers. Fig.…”

Section: Epitaxial Designmentioning

confidence: 99%

Design Optimisation of High-Brightness Laser Diodes for External Cavity Operation in the BRIDLE Project

Larkins

Bull

Kaunga-Nyirenda

et al. 2014

2014 International Semiconductor Laser Conference

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“…Diode lasers with narrow vertical far fields have been studied for many years by many groups, and various design schemes are possible (see [25][26][27][28] and references within). Currently, most high power, high-efficiency GaAs-based diode lasers make use of large optical cavity (LOC) vertical waveguide designs, with a waveguide thickness of around 1 µm, with quantum wells providing the optical gain.…”

Section: Design Approach For Simultaneous High Efficiency and Narrow mentioning

confidence: 99%

“…The resulting broadening of the optical mode reduces the modal gain, hence increasing threshold, so typically at least two quantum wells are required for reasonable performance [22]. When no special measures are taken, a waveguide thickness of > 7-8 µm is found to be necessary for operation with Θ V 95% < 30°, and this compromises performance strongly, leading to low internal efficiency, η i and high electrical resistance [25,27]. One key design challenge is that as the LOC increases in thickness, optical waveguiding due the active region itself plays an increasing role and sets a lower limit to Θ V 95% (the quantum wells have a higher refractive index, n, than the waveguide layer -see Figure 3).…”

Section: Design Approach For Simultaneous High Efficiency and Narrow mentioning

confidence: 99%

Low-loss smile-insensitive external frequency-stabilization of high power diode lasers enabled by vertical designs with extremely low divergence angle and high efficiency

et al. 2013

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Broad area lasers with narrow spectra are required for many pumping applications and for wavelength beam combination. Although monolithically stabilized lasers show high performance, some applications can only be addressed with external frequency stabilization, for example when very narrow spectra are required. When conventional diode lasers with vertical far field angle, Θ V 95% ~ 45° (95% power) are stabilized using volume holographic gratings (VHGs), optical losses are introduced, limiting both efficiency and reliable output power, with the presence of any bar smile compounding the challenge. Diode lasers with designs optimized for extremely low vertical divergence (ELOD lasers) directly address these challenges. The vertical far field angle in conventional laser designs is limited by the waveguiding of the active region itself. In ELOD designs, quantum barriers are used that have low refractive index, enabling the influence of the active region to be suppressed, leading to narrow far field operation from thin vertical structures, for minimal electrical resistance and maximum power conversion efficiency. We review the design process, and show that 975 nm diode lasers with 90 µm stripes that use ELOD designs operate with Θ V 95% = 26° and reach 58% power conversion efficiency at a CW output power of 10 W. We demonstrate directly that VHG stabilized ELOD lasers have significantly lower loss and larger operation windows than conventional lasers in the collimated feedback regimes, even in the presence of significant (≥ 1 µm) bar smile. We also discuss the potential influence of ELOD designs on reliable output power and options for further performance improvement.

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“…Many types of designs for lasers with narrow vertical far-fields have been investigated, including large and super large optical cavity ([S]LOC) [3], photonic bandgap crystal (PBC) structures [4] and designs with extra layers in the optical waveguide [5][6][7][8]. Good control of the far-field divergence is achieved in all these designs, with vertical divergence reduced from a typical 35°o r more in earlier designs, to 8-18°in structures designed for control of the vertical far-field.…”

Section: Introductionmentioning

confidence: 99%

Manufacturing‐tolerant compact red‐emitting laser diode designs for next generation applications

Elliott

Smowton

2015

IET Optoelectronics

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Quantum well laser diodes with low far-field divergence remain a requirement for many applications such as optical interconnects and data networks, pump sources and next generation holographic red-green-blue displays requiring compact, high power, visible light sources with high spatial and spectral coherence. Many designs exist, but the structure must be easy to grow reproducibly, which has commercial advantages. The authors' low far-field divergence design widens the vertical mode in such a way as to decrease the far-field divergence without significantly reducing the confinement factor, thus keeping threshold current lower. In this study, the authors calculate the sensitivity of their design, which has high refractive index mode expansion layers inserted in the cladding, to unintentional variations in layer thickness and composition during growth. They obtain consistency in measured far-fields for three wafers grown over an interval of a year, with a full-width-half-maximum vertical far-field divergence of 17°for a narrow design (Design A) and just under 13°for a very narrow design (Design B). They have demonstrated a useful, reproducible design, adding to the range of versatile semiconductor lasers available for every application.

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Combination of Low-Index Quantum Barrier and Super Large Optical Cavity Designs for Ultranarrow Vertical Far-Fields From High-Power Broad-Area Lasers

Cited by 57 publications

References 17 publications

Design Optimisation of High-Brightness Laser Diodes for External Cavity Operation in the BRIDLE Project

Design Optimisation of High-Brightness Laser Diodes for External Cavity Operation in the BRIDLE Project

Low-loss smile-insensitive external frequency-stabilization of high power diode lasers enabled by vertical designs with extremely low divergence angle and high efficiency

Manufacturing‐tolerant compact red‐emitting laser diode designs for next generation applications

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