Infrared emission from the substrate of GaAs-based semiconductor lasers

Laser & Photonics Reviews

Ziegler

Hempel

et al. 2011

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.

Section: Failure Analysis Of Devices Affected By Codmentioning

confidence: 99%

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

Laser & Photonics Reviews

Ziegler

Hempel

et al. 2011

“…In their heterolasers, they assumed the defects to be located in the (compared to a QW) rather bulklike gain material. When analyzing 808 nm emitting QW lasers, Ziegler et al [4] identified a number of SWIR contributions, among them such from defects in the GaAs substrate, which became photo-pumped by primary laser emission. For our current devices, however, the GaAs substrate is transparent for the laser light.…”

Section: Resultsmentioning

confidence: 99%

“…Such emission from devices was discovered and analyzed by Imai et al [2] and Abbot [3] at the end of the 70ies. The SWIR contributions are spectrally well separated from the (broadened) spontaneous emissions of various physical origins, see above, and are typically assigned to defect/impurity emissions [2][3][4]. A fourth, spectrally again well separated emission contribution comes from the mid infrared (MIR).…”

Section: Introductionmentioning

confidence: 99%

Short-wavelength infrared defect emission as probe for degradation effects in diode lasers

Hempel

Novel in-Plane Semiconductor Lasers XIV

Yue

et al. 2015

Self Cite

The infrared emission from 980-nm single-mode high power diode lasers is analyzed in the wavelength range from 0.8 to 7.0 µm. A pronounced short-wavelength infrared (SWIR) emission band with a maximum at 1.3 µm is found to originate from defect states located within the waveguide of the devices. The SWIR intensity is verified to represent a measure of the non-equilibrium carrier concentration in the waveguide, allowing for non-destructive waveguide mapping in spatially resolved detection schemes. The potential of this approach is demonstrated by measuring spatially resolved profiles of SWIR emission and correlating them with mid-wavelength infrared thermal emission along the cavity of devices undergoing repeated catastrophic optical damage. The enhancement of SWIR emission in the damaged parts of the cavity is due to a locally enhanced carrier density in the waveguide and allows for in situ analysis of the damage patterns. Moreover, spatial resolved SWIR measurements are a promising tool for device inspecting even in low-power operation regimes.

“…A clear distinction between bands B2 and B3 has been made in a study based on near-field scanning optical microscopy. 6 The high-resolution data allowed clear assignment of B2 as band-tail PL from the GaAs substrate and B3 as deep-level-related PL. In addition, it turned out that the long tail of the unseparated B2 + B3 bands (thin line in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…7 A BRUKER IFS66v spectrometer equipped with a PL extension was used for monitoring IR spectra from devices. 6 The sample post used in PL experiments was replaced by a water-cooled temperature-stabilized mount, which allows the laser devices to be operated under standard conditions.…”

Section: Methodsmentioning

confidence: 99%

Defect Imaging in Laser Diodes by Mapping Their Near-Infrared Emission

Ziegler

Kissel

et al. 2010

Journal of Elec Materi

Self Cite

We report additional infrared (IR) emission bands at about 1.0 eV and 1.4 eV from GaAs-based diode lasers that have their primary emission at 808 nm (1.53 eV). Four long-wavelength bands are observed. They are assigned to bandtail-related luminescence from the quantum wells (QW) as well as to interband-and deep-level-related luminescences from the GaAs substrates. Thermal radiation is detected below 0.4 eV as well. By using a thermocamera, the defect-related emission was mapped for different types of high-power diode lasers. The mechanisms causing enhanced IR emission from the devices and potential applications of this type of monitoring are addressed.