Spatial hole burning in high-power edge-emitting lasers: A simple analytical model and the effect on laser performance

Ryvkin, B. S.; Avrutin, E.A.

doi:10.1063/1.3549155

Cited by 21 publications

(19 citation statements)

References 13 publications

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“…12, we cannot obtain a simple analytical solution for the carrier density profile; on the other hand, the numerical study allows us to calculate the distributions at an arbitrary current, not just at i ) i th as in Ref. 12. It is seen that at modest currents [i ∼ (1-5) i th ], there is considerable variation in the carrier density profile with current as the LSHB establishes its effect.…”

Section: Discussionmentioning

confidence: 95%

“…Unlike the case of zero internal losses treated in Ref. 12, we cannot obtain a simple analytical solution for the carrier density profile; on the other hand, the numerical study allows us to calculate the distributions at an arbitrary current, not just at i ) i th as in Ref. 12.…”

Section: Discussionmentioning

confidence: 99%

“…The effect of (long-range) longitudinal spatial hole burning (LSHB) in edge emitting semiconductor lasers has been intensely investigated throughout the history of semiconductor laser technology. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] The LSHB effect consists of the inhomogeneous distribution of carrier density, and therefore optical gain, along the laser axis, caused by the inhomogeneous lasing light intensity distribution in the longitudinal direction. [1][2][3][4][5][6][7][8][9][10] It is in practice most pronounced in lasers of an asymmetric design, where one mirror is antireflection (AR) coated and the other mirror is high-reflection (HR) coated.…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. 12, we obtained a further simplified estimate for the photon and electron distributions (in the entire cavity) making an additional approximation of negligible intracavity losses. Under those approximations, the carrier distribution was found to stabilize at high currents, and the LSHB was shown to have no direct effect on the laser output (as could be expected from the laws of conservation).…”

Section: Introductionmentioning

confidence: 99%

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Effect of spatial hole burning on output characteristics of high power edge emitting semiconductor lasers: A universal analytical estimate and numerical analysis

Avrutin

Ryvkin

2019

Journal of Applied Physics

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The effect of longitudinal spatial hole burning on the performance of a semiconductor laser with a strongly asymmetric resonator is investigated numerically. The effects of spatial hole burning on, firstly, the non-stimulated recombination in the laser (quantified as an increased effective threshold current) and, secondly, the output efficiency are calculated and compared, and the latter is shown to dominate at high currents. It is shown that the output efficiency at high pumping levels in the presence of the spatial hole burning effect can be estimated using the standard expression as the ratio of output loss to total loss, but with the internal loss enhanced by a factor greater than one and independent on the injection level. A simple universal expression for this factor for a highly asymmetric cavity, as a function of the output mirror reflectance, is obtained and compared to numerical results, with good agreement.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of spatial hole burning on output characteristics of high power edge emitting semiconductor lasers: A universal analytical estimate and numerical analysis

Avrutin

Ryvkin

2019

Journal of Applied Physics

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“…For example, the longitudinal spatial inhomogeneity of carrier distribution has been measured using spontaneous emission through the n-side window [2] and from the side [3] of high-power laser diodes, where a higher carrier density is observed close to the HR than that to the PR facet for above-the-threshold current. The longitudinal inhomogeneity of photon and carrier density is believed to lead to output decrease due to gain saturation at high injection current [3,4,5], although some authors argued that it is an small effect [6]. Experimentally, a slightly flared laser with longitudinally varying emitter width was designed with the aim of reducing LSHB and improvement of peak output power [7,8].…”

Section: Motivationmentioning

confidence: 99%

Performance limitation and mitigation of longitudinal spatial hole burning in high-power diode lasers

et al. 2012

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Facets of high-power broad area diode lasers are typically coated with one high-reflecting and one partially reflecting layer to improve slope efficiency and maximize output power. The typical cavity lengths of commercial devices have also been progressively increasing, mainly to reduce temperature rise at the active region and improve laser performance and reliability. The asymmetric reflectivities and long cavity length, however, result in a highly inhomogeneous longitudinal profile of the photon density, which induces a spatially non-uniform carrier distribution, so-called longitudinal spatial hole burning (LSHB). A more uniform longitudinal photon and carrier distribution is believed to improve the overall gain of the cavity and reduce gain saturation, although further study is required to understand the impact of LSHB to power efficiency and its implication in laser design optimization to achieve higher peak powers. We present a phenomenological model that incorporates LSHB to describe longitudinal photon and carrier density inhomogeneity, as well as light-current characteristics of a diode laser. The impact of LSHB on the power efficiency is demonstrated through numerical calculation and can be significant under high-power operations. This presents new guidelines for high-power diode laser designs, in which LSHB imposes limits on reducing facet reflectivity and/or increasing cavity length, beyond which performance deteriorates. Alternatively, effects of LSHB can be mitigated through longitudinal patterning of the waveguide or contact to achieve high-power and high-efficiency diode lasers. We propose specially designed longitudinal patterning of electrical contact to mitigate LSHB. Ongoing device implementation will be used to demonstrate performance benefits.Keywords: longitudinal spatial hole burning, high-power diode lasers, tapered waveguide MOTIVATIONThe facets of high-power broad area laser diodes are typically coated with one high-reflecting (HR) and one partially reflecting (PR) layer to improve slope efficiency and maximize output power. On the other hand, the cavity length of high-power laser diodes has been getting progressively longer, mainly to reduce thermal resistance between the chip and heatsink, which mitigates temperature rise at the active region and improves diode performance and reliability. Both the asymmetric reflectivities and long cavity length, however, result in a highly inhomogeneous longitudinal profile of the photon density, which induces a spatially non-uniform carrier distribution within the laser cavity. Such spatial inhomogeneity, named longitudinal spatial hole burning (LSHB), has been studied theoretically [1] and measured experimentally [2,3]. For example, the longitudinal spatial inhomogeneity of carrier distribution has been measured using spontaneous emission through the n-side window [2] and from the side [3] of high-power laser diodes, where a higher carrier density is observed close to the HR than that to the PR facet for above-the-threshold current. The longitudin...

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Non-uniform longitudinal current density induced power saturation in GaAs-based high power diode lasers

Arslan

Swertfeger

Fricke

et al. 2020

Applied Physics Letters

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The output power of modern 975 nm GaAs-based broad area diode lasers is limited by increasing carrier and photon losses at high bias. We use experiment and one-dimensional calculations on these devices to reveal that higher current densities (and hence higher local recombination rates and higher losses) arise near the front facet due to spatial hole burning and that the non-uniformity is strongly affected by laser geometry, which is more severe for longer resonators and less severe for higher front facet reflectivity. Specifically, we use devices with a segmented p-contact to directly measure the current distribution along the resonator and compare this with laser simulation. Devices with a 6 mm resonator show 29% more current at the front than back, twice as large as the 15% current non-uniformity in devices with a 3 mm resonator. In contrast, increased front facet reflectivity (20% rather than 0.8%) is shown to almost halve the current non-uniformity from 29% to 18% in devices with a 6 mm resonator and reduces power saturation. Although the magnitude of current non-uniformity in experiment and theory is broadly consistent, in experiment, an additional divergence is seen in current flow (and hence recombination rate) near the facets, and earlier power saturation occurs. We discuss the possible saturation mechanisms that are not included in the simulation.

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Spatial hole burning in high-power edge-emitting lasers: A simple analytical model and the effect on laser performance

Cited by 21 publications

References 13 publications

Effect of spatial hole burning on output characteristics of high power edge emitting semiconductor lasers: A universal analytical estimate and numerical analysis

Effect of spatial hole burning on output characteristics of high power edge emitting semiconductor lasers: A universal analytical estimate and numerical analysis

Performance limitation and mitigation of longitudinal spatial hole burning in high-power diode lasers

Non-uniform longitudinal current density induced power saturation in GaAs-based high power diode lasers

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