Spatially Resolved Characterization of the Coherence Area in the Incoherent Emission Regime of a Broad-Area Vertical-Cavity Surface-Emitting Laser

Verschaffelt, Guy; Craggs, G.; Peeters, Michael; Mandre, Shyam K.; Thienpont, Hugo; Fischer, Ingo

doi:10.1109/jqe.2009.2013085

Cited by 13 publications

(10 citation statements)

References 18 publications

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“…As we have demonstrated before [15][16][17][18], BAVCSELs can be driven into a regime of spatially incoherent emission-also referred to as nonmodal emission due to the apparent breakdown of modal structures [21,22]-when pulsed. In our measurements, an oxide confined BA-VCSEL (ULM Photonics) with an aperture radius R of 25 μm is used.…”

Section: Device Characteristicsmentioning

confidence: 62%

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Characterization of a low-speckle laser line generator

et al. 2012

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The goal of our investigation is to design a low-speckle laser line generator based on partial spatially coherent laser light. Low speckle is achieved by exploiting a regime of strongly reduced spatial coherence of a broad-area vertical-cavity surface-emitting laser, which is used as the line generator's light source. A comparative experimental study of different optical configurations is conducted, leading to the design of an optimal optical system. The results of our study are also valid for other sources of partial spatially coherent emission.

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Section: Device Characteristicsmentioning

confidence: 62%

“…This type of semiconductor laser can be driven into a regime of spatially incoherent emission [15][16][17][18]. In this emission regime, the VCSEL can be considered a partially coherent, quasihomogeneous source [19].…”

Section: Introductionmentioning

confidence: 99%

Characterization of a low-speckle laser line generator

et al. 2012

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“…The spatial coherence properties at the end of the light pipe are measured using a reversing wavefront Michelson interferometer (RWI), [20][21][22] as illustrated in Fig. 4.…”

Section: Experimental Evaluation Of the Simulation Modelmentioning

confidence: 99%

The influence of a light pipe on the coherence properties in laser projectors

et al. 2014

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Light pipes are key optical components used in projection systems to transport and homogenize light from the source towards the light valve. They can provide a uniform light distribution at their output as a result of multiple internal reflections. In laser projection systems, such light pipes are useful in combination with a laser-light module consisting of one or more single-mode lasers and a rotating diffuser. The partially coherent light emanating from the rotating diffuser is transported and homogenized towards the end of the light pipe. Consequently, propagation through the light pipe will also modify the coherence properties of the laser light. In this paper, a computationally efficient simulation model is presented to propagate partially coherent light through a homogenizing rectangular light pipe. The resulting coherence function clearly differs from that of free-space propagation over the same optical path length. The implications of these results on, for example, the appearance of speckle are discussed in further detail. The simulation results are experimentally verified using a reversing wavefront Michelson interferometer. The approach described in this paper can be extended further to investigate other types of light pipes, such as tapered light pipes or even more complex ones.

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“…Numerical results also indicate that there are optimal values for current aperture in proton implanted VCSELs. The minimum injected current threshold can be achieved in VCSELs with proton implantation near the active region and confinement radius of 1.5 m, while the VCSELs with proton implantation in the middle of p-type distributed Bragg reflectors (DBRs) and confinement radius of 2.5 m can realize the minimum temperature.VCSELs are widely used for optical communications and interconnections because of the grteatly improved far-field divergence angle [1][2][3][4] . Proton implantation and selective oxide have been used to confine the laser threshold current [5,6] .…”

mentioning

confidence: 99%

“…VCSELs are widely used for optical communications and interconnections because of the grteatly improved far-field divergence angle [1][2][3][4] . Proton implantation and selective oxide have been used to confine the laser threshold current [5,6] .…”

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Threshold control in VCSELs by proton implanted depth

Zhao

Sun

Wang

et al. 2011

Optoelectron. Lett.

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The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers (VCSELs), in which the proton implanted depth and profile are main parameters. Threshold characteristics of VCSELs with various proton implanted depths are studied after optical, electrical and thermal fields have been simulated self-consistently in three dimensions. It is found that for VCSELs with confinement radius of 2 m, increasing proton implanted depth can reduce the injected current threshold power and enhance the laser temperature in active region. Numerical results also indicate that there are optimal values for current aperture in proton implanted VCSELs. The minimum injected current threshold can be achieved in VCSELs with proton implantation near the active region and confinement radius of 1.5 m, while the VCSELs with proton implantation in the middle of p-type distributed Bragg reflectors (DBRs) and confinement radius of 2.5 m can realize the minimum temperature.VCSELs are widely used for optical communications and interconnections because of the grteatly improved far-field divergence angle [1][2][3][4] . Proton implantation and selective oxide have been used to confine the laser threshold current [5,6] . The proton implanted depth and profile are two main parameters to affect the threshold current in VCSELs. A high power VCSEL with the maximum continuous wave optical output of 46 mW at room temperature was reported [7] , and various studies on thermal fields were presented in Refs. [8][9][10][11][12][13]. However, the influence of proton implanted depth on threshold thermal fields and other characteristics of VCSELs were not given in these studies.The purpose of this work is to find the optimal threshold current in VCSELs for different implanted depths.The laser is sandwiched between a pair of p and n type DBRs consisting of 20 and 27 alternating quarter-wavelength layers of AlAs and Al 0.16 Ga 0.84 As, respectively. The active region is made up of three undoped In 0.2 Ga 0.8 As quantum wells (QWs) separated by the 100 Å GaAs layer. The thickness of QW is 80 Å. In our simulation, the device is fabricated by using the H + implantation for lateral current confinement, and the potential satisfies Poisson's equation in substrate, p type and n type DBRs. 2 2 2 2 , , 1 , z z r V r z r V r r z r V .(1)The injected current density iswhere is conductivity. The carrier density N diffusion in the active region can be written aswhere d is the thickness of active region, and D n is the diffusion constant. The optical transverse i-mode i (r) in VCSELs is governed by 0 ) ( ) ( 1 2 2 2 0 2 0 r r m k r r r r r i z i i .(4)The steady-state thermal conduction equation in the laser is written as, ( ) , ( 1 l 2 2 z r Q z z r T r z r T r r r i .

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Spatially Resolved Characterization of the Coherence Area in the Incoherent Emission Regime of a Broad-Area Vertical-Cavity Surface-Emitting Laser

Cited by 13 publications

References 18 publications

Characterization of a low-speckle laser line generator

Characterization of a low-speckle laser line generator

The influence of a light pipe on the coherence properties in laser projectors

Threshold control in VCSELs by proton implanted depth

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