Near-field dynamics of broad area diode laser at very high pump levels

Hempel, Martin; Tomm, Jens W.; Baeumler, M.; Konstanzer, Helmer; Mukherjee, Jayanta; Elsaesser, Thomas

doi:10.1063/1.3664745

Cited by 17 publications

(17 citation statements)

References 14 publications

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“…This seems to be similar to the situation in cw operation. This change in defect-propagation behavior is caused by the presence of a 'threshold' energy for re-ignition of the COD [10], which might be reached at one side of the initial ignition site only. This explains why COD during cw operation often causes unidirectional defect propagation only.…”

Section: Degradation Diagram and Internal Codmentioning

confidence: 98%

Internal degradation of 980nm emitting single-spatial-mode lasers during ultrahigh power operation

et al. 2014

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Internal degradation of 980 nm emitting single-spatial-mode diode lasers during ultrahigh power operation is investigated for pulsed operation (2 µJ, 20 W). Analysis of the evolution of the emission nearfield with picosecond time resolution enables the observation of the transition from single-to multi-spatial-mode operation at elevated emission powers. Moreover, internal degradation events and subsequent defect propagation processes are in situ monitored by thermal imaging. Subsequently, these devices are opened and defect pattern are inspected by cathodo-and photoluminescence spectroscopy. The results complete earlier findings obtained with broad-area lasers and help to establish models covering defect generation and propagation in edge-emitting devices in general.

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Section: Degradation Diagram and Internal Codmentioning

confidence: 98%

Internal degradation of 980nm emitting single-spatial-mode lasers during ultrahigh power operation

et al. 2014

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“…For lower current and times closer to the leading edge of the pulse a clear zigzag motion of spots of higher intensities is visible. 8 With the rise of the active region temperature the frequency of the motion of these main filaments increases and becomes eventually imperceptible according to the temporal resolution of the setup.…”

Section: Thermal Behaviormentioning

confidence: 99%

Near-field characteristics of broad area diode lasers during catastrophic optical damage failure

et al. 2012

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One of the failure mechanisms preventing diode lasers in reaching ultra high optical output powers is the catastrophic optical damage (COD). It is a sudden degradation mechanism which impairs the device functionality completely. COD is caused by a positive feedback loop of absorbing laser light and increasing temperature at a small portion of the active material, leading to a thermal runaway on a nanosecond timescale. We analyze commercial gain-guided AlGaAs/GaAs quantum well broad area diode lasers in single pulse step tests. The near-field emission on the way to and at the COD is resolved on a picosecond time scale by a streak-camera combined with a microscope. In the final phase of the step tests the COD is occurring at ~50 times threshold current. The growth of the COD defect site is monitored and defect propagation velocities between 30 and 190 µm/µs are determined. The final shape of the damage is verified by opening the device and taking a micro-photoluminescence map of the active layer.

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“…Given that the COD has started at the front facet and lasted ∼700 ns, we find an average propagation velocity along the laser axis of ∼110 m s −1 . Assuming a comparable situation as observed in GaAs‐based devices , this velocity is even higher at the beginning of the pulse, whereas it slows down toward the end. The value exceeds values of 30 m s −1 detected in accelerated step tests with 808 nm emitting GaAs‐based devices under comparable conditions in terms of thermal load .…”

Section: Discussionmentioning

confidence: 58%

“…Assuming a comparable situation as observed in GaAs‐based devices , this velocity is even higher at the beginning of the pulse, whereas it slows down toward the end. The value exceeds values of 30 m s −1 detected in accelerated step tests with 808 nm emitting GaAs‐based devices under comparable conditions in terms of thermal load . For regular continuous wave operation 20 m s −1 have been detected for this material system .…”

Section: Discussionmentioning

confidence: 58%

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Analysis of GaN based high‐power diode lasers after singular degradation events

Mura

Vanzi

Hempel

et al. 2017

Physica Rapid Research Ltrs

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Damage patterns caused by the Catastrophic Optical Damage (COD) are analyzed in GaN‐based high‐power diode lasers. In contrast to standard failure analysis, the devices are intentionally degraded under well‐defined conditions. We find that defect growth during COD is fed by the optical mode, that is, laser energy. This process involves melting and even vaporization of quantum‐well and waveguide materials. Average defect propagation velocities along the laser axis of 110 m s−1 are observed. COD results in material loss including the formation of an empty channel. This is well consistent with material loss due to ejections of hot material out of the front facet of the device. The laser structure in the immediate vicinity of the empty channel seems to be absolutely undisturbed and no transition regions or remaining material are observed. These results are compared with earlier findings from comparable experiments obtained with GaAs‐based devices.

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Near-field dynamics of broad area diode laser at very high pump levels

Cited by 17 publications

References 14 publications

Internal degradation of 980nm emitting single-spatial-mode lasers during ultrahigh power operation

Internal degradation of 980nm emitting single-spatial-mode lasers during ultrahigh power operation

Near-field characteristics of broad area diode lasers during catastrophic optical damage failure

Analysis of GaN based high‐power diode lasers after singular degradation events

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