Assessment of the limits to peak power of 1100nm broad area single emitter diode lasers under short pulse conditions
12 Feb 2009-High-power lasers and applications (International Society for Optics and Photonics)-Vol. 7198, pp 428-436
TL;DR: In this paper, the performance and endurance limits of high power broad area devices were evaluated using commercial high current short pulse sources (>200A, <500ns) and they showed that these devices can achieve a peak power density of over 110MWcm -2 without failure for more than 3×10 7 pulses.
Abstract: High power diode lasers are the root source of optical energy in all high performance laser systems. As their performance advances, diode lasers are increasingly taking the place of other sources. Short pulse, sub-microsecond-class, high power lasers are important for many applications but historically, diode lasers have not been able to reach high enough peak pulse powers with adequate reliability, limited by physical effects such as facet failure. By combining robust facet passivation with thick super large optical cavity waveguides, greatly increased optical output power can be achieved. We present here the results of a study using commercial high current short pulse sources (>200A, <500ns) to assess the performance and endurance limits of high power broad area devices. We find that our lasers can be driven with a peak power density of over 110MWcm -2 without failure for more than 3×10 7 pulses. For example, on testing to 240A, single emitter 200m stripe 1100nm broad area devices reach 124W (46J) without failure, and 60m stripes reach 88W. In practice, high injection effects such as carrier accumulation in waveguide typically limit peak power. We review these remaining limitations, and discuss how they can be overcome. Keywords: Short pulse, diode laser, high power, COMD, reliability
Citations
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TL;DR: In this paper, a combination of detailed measurements and finite element device simulation were used for the diagnosis of power saturation in broad area diode (SAD) lasers under high current, pulse-pumped operation conditions.
Abstract: Many physical effects can potentially limit the peak achievable output power of single emitter broad area diode lasers under high current, pulse-pumped operation conditions. Although previous studies have shown reliable operation to high pump levels (240 A, 300 ns, and 1 kHz), power was found to saturate. We present here results of a systematic study to unambiguously determine the sources of this power saturation. A combination of detailed measurements and finite element device simulation were used for the diagnosis. We find that the measured power saturation is dominated by electron leakage caused by band bending at high bias due to the low mobility of the p-type waveguide. However, the power saturation is only fully reproduced when longitudinal spatial hole-burning is included. Higher powers are expected to be achieved if higher energy barriers and lower confinement factors are used to mitigate leakage and longitudinal hole-burning, respectively.
63 citations
Cites background or methods from "Assessment of the limits to peak po..."
...The device designs assessed here were previously reported in [14] and are repeated here for convenience....
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...1 shows the measured peak power as a function of drive current, with results for 60 μm and 200 μm devices reproduced from [14] for reference....
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...In our previous paper, we reported internal power densities calculated using the nominal stripe widths [14]....
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...However, as we reported previously [14], these devices can operate at such a power density for extended periods without failure–confirming the robustness of the facet passivation techniques used here....
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...In [14], devices using the four quantum well design were driven to an increased current of 240 A (300 ns, 1 kHz)....
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TL;DR: In this paper, a high power laser-thyristor structure providing low current-related and optical losses is developed, and the possibility of controlling the lasing turn-on delay time of the laser thyristor in the 8-2600 ns range is demonstrated.
Abstract: A high power laser-thyristor structure providing low current-related and optical losses is developed. The possibility of controlling the lasing turn-on delay time of the laser thyristor in the 8–2600 ns range is demonstrated. The minimum values of the energy and amplitude of the control current-density pulse, required for turning-on the laser thyristor with a peak output power of 28 W, are 1.4 nJ and 0.6 A/cm2, respectively.
16 citations
TL;DR: In this article, the authors derived the threshold conditions for closed mode lasing in terms of optical and geometrical characteristics of the semiconductor laser with a quantum-well active region and showed that the closed mode can be satisfied at a lower material gain in comparison with the Fabry-Perot cavity mode due to zero output loss.
Abstract: Threshold conditions for generation of a closed mode in the crystal of the Fabry-Perot semiconductor laser with a quantum-well active region are analyzed. It is found that main parameters affecting the closed mode lasing threshold for the chosen laser heterostructure are as follows: the optical loss in the passive region, the optical confinement factor of the closed mode in the gain region, and material gain detuning. The relations defining the threshold conditions for closed mode lasing in terms of optical and geometrical characteristics of the semiconductor laser are derived. It is shown that the threshold conditions can be satisfied at a lower material gain in comparison with the Fabry-Perot cavity mode due to zero output loss for the closed mode.
11 citations
17 Sep 2009
TL;DR: In this article, the spectral and spatial brightness of broad area diode laser systems has been investigated for increasing the peak reliable output power in CW, QCW and short pulse regimes.
Abstract: High power broad area diode lasers generate the optical energy in all high performance, high power laser systems, either
directly or as pump sources for fiber or solid state lasers. Advances in the spectral and spatial brightness of these diode
lasers are essential for further increases in system performance. Recent development work at the Ferdinand-Braun-
Institut fur Hochstfrequenztechnik has lead to significant improvements in diode laser performance. Our ongoing broad
area laser research programs, for example, seek to increase the peak reliable output power (in CW, QCW and short pulse
regimes), minimize the vertical and lateral far field emission angles, narrow the spectral line width of the emission and
increase the power conversion efficiency. Wavelengths between 800 nm and 1100 nm were investigated, with development work focused on specific applications. We present a summary of this research and discuss how performance can be further improved.
4 citations
01 Jan 2011
TL;DR: In this paper, the authors reviewed the semiconductor materials used to construct NIR diode lasers and gave an overview of peak performance published in recent articles, showing that the 300 K bandgap of compound materials from the AlInGaAsSb material system as a function of lattice constant can be used to adjust the emission wavelength through the use of nm-scale quantum well or dot structures.
Abstract: Electrically pumped diode lasers emitting in the Near Infra-Red (NIR) spectral range (785-1400 nm) have been under intensive development for over 40 years, and are in wide commercial use in a range of applications. In an updated version of [08Wen1], we review here the semiconductor materials used to construct these devices and give an overview of peak performance published in recent articles. NIR diode lasers can be made using binary, ternary, quaternary, and quinternary compound alloys in the III-V material system. Materials with direct bandgaps of the required NIR emission wavelength can be currently grown with high quality typically on either InP or GaAs wafer substrates (other substrates such as InGaAs are also possible). Quantum-size effects can be used to adjust the emission wavelength through the use of nm-scale quantum well, wire, or dot structures. Such nm-scale structures allow in addition the use of moderate levels of crystal strain, which enables further modification in the emission wavelength. Figure 9.3.1 gives an overview of the 300 K bandgap of compound materials from the AlInGaAsSb material system as a function of lattice constant, as used in the majority of NIR diode lasers.
References
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TL;DR: In this article, the degradation mechanisms and enhancement factors of AIGaAs/GaAs light sources reliability and degradation of InGaAsP/InP surface emitting type LEDs reliability in LEDs and laser diodes degradation of MBE-and MOVPE-grown lasers degradation of bonds and heat sinks degradation modes and lifetime of semiconductor LEDs and lasers
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383 citations
"Assessment of the limits to peak po..." refers background in this paper
...The failure rate, F(t), of high power broad area lasers depends typically on temperature and drive current, described via the equation, F(t)∝ exp(-Ea / kBT)I m , where Ea is an activation energy for thermally driven effects, T the temperature of the quantum well (junction) in Kelvin and m an acceleration factor for current driven effects [15,16]....
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TL;DR: In this article, a two-stage process consisting of removal of thermodynamically unstable species and facet sealing with a passivation layer is proposed for the passivation of mirror facets of Al-free active region high-power semiconductor diode lasers.
Abstract: A novel process for the passivation of mirror facets of Al-free active-region high-power semiconductor diode lasers is presented. Designed for technological simplicity and minimum damage generated within the facet region, it combines laser bar cleaving in air with a two-step process consisting of 1) removal of thermodynamically unstable species and 2) facet sealing with a passivation layer. Impurity removal is achieved by irradiation with beams of atomic hydrogen, while zinc selenide is used as the passivating medium. The effectiveness of the process is demonstrated by operation of 808-nm GaAsP-active ridge-waveguide diode lasers at record optical powers of 500 mW for several thousand hours limited only by bulk degradation.
158 citations
"Assessment of the limits to peak po..." refers methods in this paper
...After cleaving, the facets were first passivated [11], before having dielectric coating applied to the front and back facets to yield reflectivities of 1....
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TL;DR: In this paper, the authors derived analytical approximations for the equivalent transverse spot size, d/Γ (<5% error), and the transverse beamwidth of broad-waveguide-type diode lasers, over a wide range in waveguide width: from the first-ordermode cutoff to the third-order-mode cutoff.
Abstract: Accurate analytical approximations are derived for the equivalent transverse spot size, d/Γ (<5% error), and the transverse beamwidth θ1/2 (<2% error), of broad-waveguide-type diode lasers, over a wide range in waveguide width: from the first-order-mode cutoff to the third-order-mode cutoff. The analytical formulas are found to be in good agreement with experimental values. For low-series-resistance and thermal-resistance devices, it is found that the junction-temperature rise ΔTj in continuous wave (CW) operation is a strong function of both the characteristic temperature T1 for the external differential quantum efficiency ηD as well as of the heatsink thermal resistance. If the device has relatively temperature-insensitive ηD (i.e., T1≳1000 K) the maximum CW power as well as the power density at catastrophic optical mirror damage, PCOMD, are limited, for a given active-region material, only by the heatsink heat-removal ability. For large d/Γ, 0.97 μm emitting, 100 μm stripe InGaAs/InGaAs(P)/GaAs device...
120 citations
"Assessment of the limits to peak po..." refers methods in this paper
...One successful approach is to increase the number of quantum wells, as detailed in Reference [10]....
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...A widely used quality criterion for a given high power diode laser structure is the internal optical power density at peak power, PCOMD , determined via equation (1) and taken from Reference [12]....
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...The notation PCOMD is used to be consistent with reference [12], where the peak power is limited by failure at the facet due to Catastrophic Optical Mirror Damage, COMD....
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TL;DR: In this paper, the authors compare ridge-waveguide laser with trench widths of 5 and 20 mum, and show that the 5mum trench-width device exhibits a much more stable lateral far-field.
Abstract: We compare ridge-waveguide lasers with trench widths of 5 and 20 mum. The emission wavelength is around 1064 nm and the ridge width is 5 m. The maximum output power exceeds 2 W. The 5-mum trench-width device exhibits a much more stable lateral far-field. The full-width at half-maximum of the vertical far-field profile is only 15deg due to a super-large optical cavity.
78 citations
"Assessment of the limits to peak po..." refers methods in this paper
...Instead, example devices from reference [18] were tested....
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01 Jan 2000
TL;DR: In this paper, all current methods of incoherent as well as of coherent beam combining are described and judged with respect to their present and future potential, and all of them are compared with each other.
Abstract: Diode-laser systems have a good chance to be used as light sources for direct applications. For this purpose a large number of relatively weak light bundles originating from individual oscillators have to be coupled to a single powerful beam. The coupling may be done in a completely incoherent way in cases where only a moderate beam quality is appropriate or with increasing degrees of coherence corresponding to applications where high demands on the quality are necessary. In this article all current methods of incoherent as well as of coherent beam combining are described and judged with respect to their present and future potential.
66 citations