Analysis of thermal images from diode lasers: Temperature profiling and reliability screening

Kozłowska, Anna; Latoszek, Mateusz; Tomm, Jens W.; Weik, F.; Elsaesser, Thomas; Zbroszczyk, M.; Bugajski, M.; Spellenberg, B.; Baßler, M.

doi:10.1063/1.1928319

Cited by 40 publications

(36 citation statements)

References 9 publications

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“…3.1., mainly because of the low absorbance (emittance) of the (thin) heated surface region and huge background contributions [142,143]. Thermography has, however, been applied successfully for T bulk -analysis [144][145][146][147][148][149][150]. Moreover, the thermal runaway in COD creates a 'thermal flash' of Planck's radiation which can be detected by thermography.…”

Section: Further Approaches For Facet Temperature Analysismentioning

confidence: 99%

Mechanisms and fast kinetics of the catastrophic optical damage (COD) in GaAs‐based diode lasers

Tomm

Ziegler

Hempel

et al. 2011

Laser & Photonics Reviews

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Semiconductor lasers are the most efficient manmade narrow-band light sources and convert up to threequarters of electric energy into light. High-power diode lasers are characterized by very high internal power densities in their small cavity, resulting in local heating and sometimes device degradation. Catastrophic optical damage (COD) of diode lasers is a relevant degradation mechanism and limit for reaching ultrahigh optical powers. An overview is given on research activities targeting the mechanisms being relevant for the COD process in GaAs-based diode lasers emitting in the 630-1100 nm range. The discussion of experiments, where COD is artificially provoked, represents the main topic. The sequence of events and fast kinetics taking place on a nanosecond to microsecond time scale are addressed. A particular emphasis is laid on recent experimental work performed in the authors' laboratories. Paving the way for knowledge-based solutions towards more robust diode lasers represents the ultimate goal of this work. COD diagram determined for a batch of broad-area AlGaAs diode lasers. The time to COD within a single current pulse is plotted versus the actual average optical power in the moment when the COD takes place. Full circles stand for clearly identified COD events (right ordinate), whereas open circles (left ordinate) represent the pulse duration in experiments, where no COD has been detected. A borderline (gray) exists between two regions, i. e., parameter sets, of presence (orange) and absence of COD (blue). This borderline is somewhat blurred because of the randomness in filamentation of the laser nearfield and scatter in properties of the involved individual devices.

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Section: Further Approaches For Facet Temperature Analysismentioning

confidence: 99%

Mechanisms and fast kinetics of the catastrophic optical damage (COD) in GaAs‐based diode lasers

Tomm

Ziegler

Hempel

et al. 2011

Laser & Photonics Reviews

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“…If we shift the focal plane from the facet to the defect inside the cavity, however, we can image a localized hot spot, see Figure 2(c). Moreover, we have demonstrated 3 that thermal profiling helps recognize defects that cannot be detected by simple visual inspection. Near-IR images of diode lasers can show signs of slow degradation.…”

Section: Figure 3 Front View Thermographic Images Acquired In the Nementioning

confidence: 98%

“…[3][4][5] Our basic idea for this measurement relies on the fact that both defect creation and accumulation are typically accompanied by a local temperature increase that can be directly detected by micro-thermography. Moreover, the extension of this measurement system to include two spectral channels, together with analysis of thermal transients, allows our system to distinguish between pure thermal radiation and any other parasitic emission, such as deep-level luminescence.…”

Section: Micro-thermography Previously Used For the Inspection Of Sementioning

confidence: 99%

Micro-thermography enables rapid inspection of defects in diode lasers

Kozłowska¹

2006

SPIE Newsroom

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Micro-thermography, previously used for the inspection of semiconductor circuits, is now applied to detecting defects in diode lasers. A multi-channel measurement system is used to distinguish between pure thermal radiation and parasitic emissions. This allows effects related to both fast and slow degradation of diode lasers to be monitored, making micro-thermography a highly-attractive tool for device screening.Diode lasers (DLs) are efficient light sources that are widely used in telecommunication, computer equipment, medicine, telemetry and material processing. Though the technology of lowpower devices has already reached a level of maturity, the reliability of high-power DLs remains an issue. Diode laser bars could be widely used-e.g. for optical pumping of solid-state lasers-but due to reliability problems they frequently lose when in competition even with conventional lamp sources. In order to increase reliability, manufacturers need a better way to inspect devices for defects before shipping the DLs to customers.Past approaches used to identify the defects inside the diode laser include microscopic, spectroscopic, and electrical methods. These methods are helpful in understanding and solving the degradation problems, but their complexity prevents their use in an industrial environment. Micro-thermography seems to be an ideal solution, especially if we take into account the enormous progress in the field of infrared (IR) imaging: improved spatial resolution, quasi-real-time operation and high detection sensitivity. Thermography has already been implemented for the inspection of high-power laser bar stacks.2 Also, our recent work has been devoted to the analysis of various thermal problems in DLs and DL bars. 3-5Our basic idea for this measurement relies on the fact that both defect creation and accumulation are typically accompanied by a local temperature increase that can be directly detected by micro-thermography. Moreover, the extension of this measurement system to include two spectral channels, together with analysis of thermal transients, allows our system to distinguish between pure thermal radiation and any other parasitic emission, such as deep-level luminescence.To investigate problems related to fast and slow degradation of diode lasers we used devices made in-house. These were based on a double-barrier separate confinement heterostructure emitting at 808nm.6 Their design is intended to reduce fast-axis beam divergence. Figure 1 shows a schematic of our thermographic system. We used a camera sensitive in the wavelength range 1.5 -5.5μm. Two filters, F1 and F2, define spectral channels in the near and mid IR. We captured mid-IR thermal images of DLs that were candidates for fast degradation. A DL with a hot spot at the front facet is shown in Figure 2(a). In the case of another DL, the defect is located deeper in the substrate and is visible as an ex- Continued on next page

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“…Recently, important research efforts have been done to improve the performance and analysis the reliability of laser diodes (LDs). Analysis of thermal images of the laser diodes is carried out using imaging thermography method, and hot spots at front facet, in the substrate, and in the active region are observed [1]. The thermal resistance could be reduced up to 40% by a proper design of the laser chip and epi-down bonding [2].…”

Section: Introductionmentioning

confidence: 99%

Thermal resistance analysis related to the degradation of GaAs-Based laser diodes

Qiao

Feng

Wang

et al. 2010

2010 10th IEEE International Conference on Solid-State and Integrated Circuit Technology

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Thermal transient measurement of the 808 nm GaAs-Based laser diodes (LDs) before and after the constant current stress are presented and discussed in this paper. Aging tests are carried out under the conditions of the constant current stress (1 A) for 255 hours. The total thermal resistance increases from 7.0 to 8.8 /W before and after degradation. Furthermore, the contribution of each component to the total thermal resistance has been obtained from the differential structure function and cumulative structure function before and after stress. The thermal resistance of chip maintain almost constant before and after stress, while significant increase in the thermal resistance of solder layer (indium attaching material) and package body are observed after degradation. These results indicate that the thermal properties of solder layer and package body degrade apparently as contrast to the chip of LDs. The thermal properties of solder layer and package body have critical effects on the performance of LDs. Thus the performance of LDs could be improved through optimizing of solder material and package body.

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Analysis of thermal images from diode lasers: Temperature profiling and reliability screening

Cited by 40 publications

References 9 publications

Mechanisms and fast kinetics of the catastrophic optical damage (COD) in GaAs‐based diode lasers

Mechanisms and fast kinetics of the catastrophic optical damage (COD) in GaAs‐based diode lasers

Micro-thermography enables rapid inspection of defects in diode lasers

Thermal resistance analysis related to the degradation of GaAs-Based laser diodes

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