In-phase, coherent photonic crystal vertical-cavity surface-emitting laser arrays with low divergence

Siriani, Dominic F.; Choquette, Kent D.

doi:10.1049/el.2010.0754

Cited by 44 publications

(23 citation statements)

References 15 publications

(13 reference statements)

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“…4 of this book). Coherently coupled arrays with low beam divergence are among the more recent prospects [40].…”

Section: Other Research Not Covered By the Chaptersmentioning

confidence: 99%

VCSELs: A Research Review

Michalzik

2012

Springer Series in Optical Sciences

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This chapter attempts to briefly review the research history of verticalcavity surface-emitting lasers (VCSELs). Based on the contents of previous monographs on VCSELs written in English, we motivate the selection of topics in the present book and give an introduction to the individual chapters. Moreover, we mention some other research that is not covered in a dedicated chapter in order to provide the readers with even deeper insights into VCSEL research. Future directions and opportunities are also indicated.

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“…4 of this book). Coherently coupled arrays with low beam divergence are among the more recent prospects [40].…”

Section: Other Research Not Covered By the Chaptersmentioning

confidence: 99%

VCSELs: A Research Review

Michalzik

2012

Springer Series in Optical Sciences

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“…We discuss both top and bottom-emitting coherent VCSEL arrays that can operate in the in-phase mode. The key to their operation is strongly coupled leaky-mode operation, which can be achieved using ion implantation to define a periodically arrayed gain regions, and a 2D photonic crystal hole pattern etched into the top facet to control the lateral modes [1,2]. The brightness of VCSEL arrays typically suffer from either incoherence between elements [3] or an out-of-phase far field profile [4], either of which can arise from periphery current injection.…”

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confidence: 99%

“…Here we report a simple self-aligned process to demonstrate inphase continuous wave (CW) emission in both top and bottom emitting coherently coupled VCSEL arrays. We also show for top emitting coherently coupled arrays that the phase can be varied by differential current injection over a full range of π which enables beam steering at modulation speeds up to 100 MHz [6].The VCSEL arrays under study are arranged in a 2x1 or 2x2 configuration, where the fabrication procedure has been described in previous work [1,2]. The top emitting arrays emit at 850 nm while the bottom (substrate) emitting arrays emit at 980 nm.…”

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“…While this in-phase mode dominates at a particular level of current injection, multiple modes are evident at higher current injection. Mode stability can be provided by a photonic crystal pattern [1,2].Near and far-field measurements are also taken for fixed current injection through one contact and varying current injection into another contact. In this manner the relative phase between the array elements can be varied, and thus the far-field can be electronically steered [7].…”

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confidence: 99%

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Two-dimensional coherently coupled vertical cavity laser arrays

Johnson

Siriani

Fryslie

et al. 2013

2013 IEEE Photonics Society Summer Topical Meeting Series

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Two-dimensional coherently coupled vertical cavity surface emitting laser (VCSEL) arrays have long been pursued for narrow divergence and high brightness applications. We discuss both top and bottom-emitting coherent VCSEL arrays that can operate in the in-phase mode. The key to their operation is strongly coupled leaky-mode operation, which can be achieved using ion implantation to define a periodically arrayed gain regions, and a 2D photonic crystal hole pattern etched into the top facet to control the lateral modes [1,2]. The brightness of VCSEL arrays typically suffer from either incoherence between elements [3] or an out-of-phase far field profile [4], either of which can arise from periphery current injection. Bottom-emitting arrays can circumvent these difficulties by allowing direct current injection into all laser elements. Previous pulsed coherent bottom emitting arrays have employed reflectivity modulation to select the supermode, which necessarily leads to out-of-phase emission [5]. Here we report a simple self-aligned process to demonstrate inphase continuous wave (CW) emission in both top and bottom emitting coherently coupled VCSEL arrays. We also show for top emitting coherently coupled arrays that the phase can be varied by differential current injection over a full range of π which enables beam steering at modulation speeds up to 100 MHz [6].The VCSEL arrays under study are arranged in a 2x1 or 2x2 configuration, where the fabrication procedure has been described in previous work [1,2]. The top emitting arrays emit at 850 nm while the bottom (substrate) emitting arrays emit at 980 nm. The photonic crystal pattern etched into the top mirror limits the number of lasing modes and provides stable index guiding. The defects in the hole pattern create the array elements and are aligned with implant apertures approximately the same size. The latter confines the current to the individual elements, as shown in Fig. 1 for either top emitting or bottom emitting geometry. The top metal contact and uppermost semiconductor layer is etched with a focused ion beam for electrical isolation of each defect cavity to allow preferential current injection. For the bottom emitting arrays, a Au layer with 3 µm thick 7x7 µ m Au squares with a 9 µm pixel pitch is deposited on the high reflectivity DBR mirror. The thick Au squares block subsequent proton implantation, providing self-aligned current confinement to the array elements. The bottom emitting arrays shown here do not have photonic crystal mode control.Shown in Fig. 2 are near and far field profiles from in-phase operation of the arrays. The near field modal pattern of the 2x2 top emitting array in Fig. 2(a) exhibits fringes between the elements [1], which is indicative of the leaky-mode behavior [2]. The current injection path defined by the implantation suppresses the index which enables in-phase operation, as shown in Fig. 2(b). However due to current crowding issues, larger arrays only exhibit out-of-phase operation (with an on-axis far field null) or the inn...

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“…More recently, photonic crystal VCSELs [2,3] opened a way to engineer singlemode polarisation stable VCSELs with large apertures, realise field-coupled arrays, and produce lasers with different emission wavelengths on the same wafer. Yet still the industrial progress of VCSELs is limited by the GaAs-AlGaAs materials system.…”

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Passive cavity surface emitting laser

et al. 2011

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Demonstrated is a vertical cavity surface emitting laser (VCSEL) formed by a passive half-wavelength cavity and a quarter-wavelength active gain region, wherein the said gain region resides in one of the VCSEL's distributed Bragg reflectors. The device concept invites extensive opportunities for innovation in the combinations of materials and gain region placements that may be used to construct surface emitting devices.Introduction: GaAs-based vertical cavity surface emitting lasers (VCSELs) [1] are broadly used in sensing and optical communications.The key advantages of VCSELs include a low threshold current density, high power conversion efficiency, narrow emission spectrum, high temperature stability, planar processing, high yield, and high reliability. More recently, photonic crystal VCSELs [2, 3] opened a way to engineer singlemode polarisation stable VCSELs with large apertures, realise field-coupled arrays, and produce lasers with different emission wavelengths on the same wafer. Yet still the industrial progress of VCSELs is limited by the GaAs-AlGaAs materials system. This system provides a relatively high refractive index step for wavelengths longer than about 750 nm between its binary and quasi-binary members, and thus relatively thin and highly-reflective distributed Bragg reflectors (DBRs) with significant heat conductivity. Despite notable success in basic research [4], industrial applications of InP-, GaSb-, GaN-, and short wavelength (red) GaAs-based VCSELs [5] remain quite limited or in full stasis. For these VCSEL products the main obstacle for broader market penetration is the small step in the refractive indices of the DBRs. As is well known, a small index contrast in monolithic semiconductor DBRs leads to a narrow DBR stopband. The narrow-band DBRs must be grown with extreme precision and a large number of periods to provide the necessary power reflectance for lasing. Moreover, in low index contrast VCSELs the resonant optical field intensity significantly extends outside of the microcavity region. This reduces modal gain and heat conductivity and leads to inefficient devices.In this Letter we report the performance of oxide-confined 850 nm GaAs-based VCSELs with an InAs submonolayer quantum dot [6] active region incorporated into a high-index l/4-thick section of the top DBR, wherein the gain region is displaced five DBR periods from a passive cavity region. The optical field intensity in the VCSEL's cavity is generated by the gain section with a gain maximum spectrally within the forbidden gap of the DBR. The passive resonant cavity can be made of a large variety of materials including dielectric layers that may or may not be lattice matched and have a large refractive index step. The passive resonant cavity may contain for example: metal insertions, materials with a compensated dependence of the refractive index on temperature, an electro-optic or -absorption modulator, a photonic crystal structure, or a nanometre-patterned medium. Since the optical field intensity in the cavity and the wi...

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In-phase, coherent photonic crystal vertical-cavity surface-emitting laser arrays with low divergence

Cited by 44 publications

References 15 publications

VCSELs: A Research Review

VCSELs: A Research Review

Two-dimensional coherently coupled vertical cavity laser arrays

Passive cavity surface emitting laser

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