Temperature Analysis of Threshold Current in Infrared Vertical-Cavity Surface-Emitting Lasers

Chen, Chen; Leisher, Paul O.; Allerman, Andrew A.; Geib, K.M.; Choquette, Kent D.

doi:10.1109/jqe.2006.881828

Cited by 44 publications

(23 citation statements)

References 20 publications

(9 reference statements)

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“…4. The threshold current shows a parabolic dependence on temperature which typical for VCSELs that exhibit a gain offset design [5], [16].…”

Section: Resultsmentioning

confidence: 95%

“…The variation of threshold current (I th ) with temperature can be well approximated by the quadratic relationship [16] …”

Section: Resultsmentioning

confidence: 99%

“…The third parameter, β indicates the VCSEL's threshold current sensitivity to temperature change. The parameter β is governed by the quantum well design and overall effective index of the cavity [16]; a larger value of β implies higher temperature sensitivity of the threshold current. The model parameters extracted for the VCSEL used here are α = 5.64 mA, β = 5.04 × 10 −4 mA/ • C 2 and T min = 22.9 • C. Moving along the temperature axis, beyond the T min , mismatch between the gain and the cavity resonant mode increases resulting in higher drive currents necessary to reach the threshold.…”

Section: Resultsmentioning

confidence: 99%

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Temperature and current dependence of doppler SNR in a VCSEL based self-mixing sensor

et al. 2009

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This paper proposes a method for maintaining the maximum signal-to-noise ratio (SNR) of the signal obtained from the self-mixing sensor based on a Vertical-Cavity SurfaceEmitting Laser (VCSEL). The SNR of the Doppler self-mixing signal was investigated experimentally as a function of laser driving current and ambient temperature. It was found that the locus of the maximum SNR in the current-temperature space can be well approximated by the simple analytical model based on the temperature behaviour of the VCSELs threshold current. A selfmixing Doppler signal was acquired from the variation in VCSEL junction voltage rather than from a conventional variation in laser optical power to reduce the complexity of the system. It was found that the optimum sensor performance over a wide range of ambient temperatures can be achieved by tuning the laser current according to the proposed model. This enables the sensor to operate without temperature stabilisation making it attractive for mobile applications and applications with limited power supply.

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“…4. The threshold current shows a parabolic dependence on temperature which typical for VCSELs that exhibit a gain offset design [5], [16].…”

Section: Resultsmentioning

confidence: 95%

“…The variation of threshold current (I th ) with temperature can be well approximated by the quadratic relationship [16] …”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Temperature and current dependence of doppler SNR in a VCSEL based self-mixing sensor

et al. 2009

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“…Subsequent measurements on a probing station showed that the electrical isolation between adjacent elements was of the order of 5 MΩ, which suggests that the increase in SNR was due solely to the temperature rise in the sensing laser. The injection current for the optimum SNR also slightly increases when the neighbouring lasers are turned on, which suggests that the initial temperature of the laser array is on the hot side of the parabolic threshold current temperature profile [12,18]. Further increase in operating current of the neighbouring VCSELs leads to a monotonic increase in maximum achievable SNR.…”

Section: Achievable (Over a Range Of Operating Injection Currents)mentioning

confidence: 97%

Self-mixing sensing system based on uncooled vertical-cavity surface-emitting laser array: linking multichannel operation and enhanced performance

et al. 2014

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We compare the performance of a self-mixing (SM) sensing system based on an uncooled monolithic array of 24×1 vertical-cavity surface-emitting lasers (VCSELs) in two modes of operation: single active channel and the concurrent multichannel operation. We find that the signal-to-noise ratio of individual SM sensors in a VCSEL array is markedly improved by multichannel operation, as a consequence of the increased operational temperature of the sensors. The performance improvement can be further increased by manufacturing VCSEL arrays with smaller pitch. This has the potential to produce an imaging system with high spatial and temporal resolutions that can be operated without temperature stabilization.

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“…Subsequent measurements on a probing station showed that the electrical isolation between adjacent elements was of the order of 5 MΩ. The injection current for the optimum SNR also slightly increases when the neighbouring lasers are turned on, which follows the increase in the threshold current with temperature as observed in a single channel system [122,207]. This suggests that the increase in SNR is due solely to the temperature rise in the sensing laser.…”

Section: Introductionmentioning

confidence: 70%

Skin cancer detection using laser imaging

Mowla¹

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Endeavors to develop a non-invasive and reliable device to detect different types of skin cancer in its early stages have been undertaken over the past few years. Although some advances have been made towards such developments, there remains great scope for the development of a non-expensive, compact, reliable, safe, easy to use, fast, sensitive, and non-invasive device. This project will apply the innovative laser feedback interferometry (LFI) technique to skin cancer detection via laser imaging using near-infrared vertical cavity surface emitting lasers (VCSELs). In this project, the science behind lighttissue interactions has been explored and skin imaging modalities have been elaborately studied. As a result, LFI has been exploited in various configurations to image different modalities such as Doppler flowmetry and confocal reflectance. In addition to single modality imaging, dual-modality imaging has also been proposed and conducted experimentally, to image Doppler flowmetry and confocal reflectance at the same time, using an integrated LFI system. It is shown that dual-modality imaging can yield images with higher contrast which provide more information about morphological and functional characteristics of a target under test.In addition to two-dimensional LFI imaging, three-dimensional imaging systems have also been studied and employed in the laboratory. A tomographic image identifies tissue volume with altered optical properties due to cancerous or other malignant tissue processes. We applied the three-dimensional imaging system to different types of keratinocyte skin cancer phantoms and results show high level of sensitivity in providing tomographic images. Using high numerical aperture lenses, making images at resolutions down to micrometer scales is possible, which is promising for microscopy of biological structures.Furthermore, parallel LFI imaging using an array of 24 VCSELs was also studied theoretically and experimentally as a part of this work. A VCSEL array was used in a parallel read-out LFI imaging system to develop a fast and high resolution device, which eliminates the need to scan mechanically in one dimension.Investigating the complex interactions of the laser beam and tissue requires a powerful and robust simulation technique. Monte Carlo was used as a simulation technique to model the light-tissue interactions occurring in the optical systems in this work. Firstly, we tested and validated the Monte Carlo main engine which was developed in the group, by studying morphological aspects of the simulated and experimental signals in a laser Doppler velocimetry system, and deep insight into the nature of the LFI Doppler spectrum and further conclusions were drawn. Secondly, the Monte Carlo engine was used in iii modeling and analyzing of optical systems, in this work.We developed tissue phantom making techniques which were used to examine the experimental ideas in place of biological samples which are difficult to obtain and work with. Therefore, tissue phantom techniques were studie...

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Temperature Analysis of Threshold Current in Infrared Vertical-Cavity Surface-Emitting Lasers

Cited by 44 publications

References 20 publications

Temperature and current dependence of doppler SNR in a VCSEL based self-mixing sensor

Temperature and current dependence of doppler SNR in a VCSEL based self-mixing sensor

Self-mixing sensing system based on uncooled vertical-cavity surface-emitting laser array: linking multichannel operation and enhanced performance

Skin cancer detection using laser imaging

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