Two-dimensional phase-locked arrays of vertical-cavity semiconductor lasers by mirror reflectivity modulation

Orenstein, Meir; Kapon, E.; Stoffel, N. G.; Harbison, J. P.; Florez, L. T.; Wullert, John R.

doi:10.1063/1.105218

Cited by 118 publications

(41 citation statements)

References 6 publications

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“…But high order transverse modes arise [8] in small-diameter VCSEL, while in large-diameter VCSELs spontaneous filamentation results from structural nonuniformities [9]. Other 1D structures that can be produced as a macroscopic single domain material are self-organized cholesteric liquid crystals [10].…”

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confidence: 99%

Large Coherence Area Thin-Film Photonic Stop-Band Lasers

2001

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We demonstrate that the shift of the stop-band position with increasing oblique angle in periodic structures results in a wide transverse exponential field distribution corresponding to strong angular confinement of the radiation. The beam expansion follows an effective diffusive equation depending only upon the spectral mode width. In the presence of gain, the beam cross section is limited only by the size of the gain area. As an example of an active periodic photonic medium, we calculate and measure laser emission from a dye-doped cholesteric liquid crystal film. DOI: 10.1103/PhysRevLett.86.1753 Photonic band-gap materials hold promise as a platform for a new generation of efficient, compact photonic devices. The initial excitement generated by these materials has been sustained by the discovery of new physical effects leading to new applications [1][2][3]. Yablonovitch has predicted that the lasing threshold can be reduced by introducing a defect into an otherwise periodic photonic band-gap structure. Since spontaneous emission is suppressed in the band gap, excitation will not then be drained by modes other than the lasing mode [2]. In addition, the long dwell time of such localized defect modes reduces the gain required to reach the lasing threshold. Lasing has recently been observed in 2D photonic crystals [4], and promising 3D photonic crystals have been fabricated [5]. The threshold for lasing may even be suppressed at defect modes in periodic structures that do not possess a full 3D photonic band gap, such as in 1D periodic samples, including vertical cavity surface emitting lasers (VCSELs) [6]. Recently, lasing at the band edge has been demonstrated in dye-doped cholesteric liquid crystals (CLCs). In these chiral structures, a stop band exists for circularly polarized light that has the same sign of rotation as the CLC structure. Since the dwell time within the sample for emitted photons is enhanced near the band edge, the lasing threshold is also substantially reduced [7].In this Letter, we present an unexpected conjunction of strong expansion of the region of phase coherence within the medium and weak divergence of the output beam, which is made possible in a periodic structure possessing a photonic stop band. Our calculations show that a diffusionlike spreading of the coherent field leads to wide area lasing at the edge of a photonic stop band or at a localized state in the middle of the stop band. These results are supported by measurements of the spatial profile of laser emission from a promising organic material -a dye-doped cholesteric liquid crystal. Since the maximum excitation energy is proportional to the laser area, large-area thin-film devices provide a new approach for high-power lasers. While liquid crystals are not stable at the elevated temperatures produced by intense laser excitation, polymeric CLCs may be promising materials for large-area high-power lasers.Though lasing has not yet been observed in 3D periodic structures, the enhanced photon dwell times and microcavity effects in l...

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confidence: 99%

Large Coherence Area Thin-Film Photonic Stop-Band Lasers

2001

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“…That is, the mode can be defined as (assume each element contains a fundamental mode) (4) where is the number of standing wave peak in the inter-element region [26]. For example, the mode in Fig.…”

Section: -D Antiguided Vcsel Array Structure: Effective-index Modelmentioning

confidence: 99%

“…A 3-D finite element analysis is employed to study the thermal behavior of a typical 4 4 array for both of the top-emitting and bottom-emitting cases, and the resulting 1-D cut of the cavity region's temperature increase is plotted in Fig. 16.…”

Section: Thermal Effects On Array Performancementioning

confidence: 99%

“…Previous VCSEL array designs have attempted to select a single-mode (i.e., all elements phase locked) from the allowed bands of guided-modes supported by the 2-D photonic lattice. The conventional approaches start with a large-area VCSEL structure, and incorporate a means to separate the individual array elements [3]- [6] such as: 1) pattern the array reflectivity so that the elements under the higher reflectivity regions have a lower threshold gain [3], [4]; 2) restrict the gain (injection current) to individual elements by selective ion implantation [5]; and 3) selectively etch the top surface so that the unetched regions form the higher-cavity-array elements [6]. These attempts to fabricate VCSEL arrays have successfully demonstrated phase locking among the array elements, emitting partially-coherent beams.…”

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Modal properties of two-dimensional antiguided vertical-cavity surface-emitting laser arrays

Zhou

Mawst

Dai

2002

IEEE J. Quantum Electron.

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Abstract-We present a detailed analysis on 2-D (4 4 square-lattice) antiguided vertical-cavity surface-emitting laser (VCSEL) arrays based on the effective-index model. The calculation shows that the array can operate under 2-D resonant coupling, provided that the resonance condition in both the horizontal and vertical directions is satisfied. Consequently, the resonant-mode edge radiation loss is inversely proportional to the number of array elements along one direction for a array. Low-edge-loss out-of-phase and adjacent array modes are found to compete with the in-phase resonant mode. While the 3-D gain overlap is not a significant factor in modal discrimination, the introduction of inter-element loss allows the in-phase mode to exhibit the lowest threshold gain for a wide range of inter-element width, (1 0.5 m for 980-nm wavelength devices). The 2-D antiguided array results from shifting the cavity resonance between the element and inter-element regions and is fabricated by selective chemical etching and two-step metalorganic chemical vapor deposition (MOCVD) growth. Diffraction-limited in-phase and out-of-phase array mode operation is observed from top-emitting arrays, depending on the inter-element width. Substrate-emitting array structures are investigated as a means to lower heating and increase the coherent output power.

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“…However, stable, high-power, diffractionlimited beam operation from two-dimensional ͑2D͒ VCSEL arrays has not been realized. [1][2][3] In addition, all previously reported phase-locked 2D VCSEL arrays operate in either an out-of-phase mode or a mixture of various modes, characteristic of weakly index guided arrays, with poor intermodal discrimination. External phase shifters have also been used on optically pumped VCSEL arrays to obtain ''in-phase mode-like'' emission, 4 however the beam is quite broad.…”

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confidence: 99%

Two-dimensional phase-locked antiguided vertical-cavity surface-emitting laser arrays

Zhou

Mawst

2000

Applied Physics Letters

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4ϫ4 antiguided phase-locked vertical-cavity surface-emitting laser ͑VCSEL͒ arrays have been fabricated by a selective etching process and metalorganic chemical vapor deposition regrowth. Stable, diffraction-limited output is observed corresponding to either in-phase or out-of-phase mode operation, depending on the interelement spacing width. Calculations indicate resonant leaky-wave coupling occurs for interelement spacings corresponding to an integral number of half-waves of the radiation leakage from each VCSEL region, and the use of interelement loss is effective in suppressing nonresonant modes. © 2000 American Institute of Physics. ͓S0003-6951͑00͒04141-3͔Coupled vertical-cavity surface-emitting laser ͑VCSEL͒ arrays are an attractive means to increase the coherent output power of VCSELs. However, stable, high-power, diffractionlimited beam operation from two-dimensional ͑2D͒ VCSEL arrays has not been realized. [1][2][3] In addition, all previously reported phase-locked 2D VCSEL arrays operate in either an out-of-phase mode or a mixture of various modes, characteristic of weakly index guided arrays, with poor intermodal discrimination. External phase shifters have also been used on optically pumped VCSEL arrays to obtain ''in-phase mode-like'' emission, 4 however the beam is quite broad. Here we will present a novel monolithic antiguided 2D VCSEL array with stable in-phase mode emission. The progress in phase-locked 2D VCSEL arrays parallels closely that of edge-emitting phase-locked arrays. Weak coupling and poor intermodal discrimination found in evanescently coupled edge-emitting laser arrays has severely limited their single-mode output power. 5 By contrast, antiguided array structures exhibit strong leaky-wave coupling leading to high intermodal discrimination. As a result, edge-emitting antiguided arrays have demonstrated coherent output power in the watt range. 6 The large built-in index step and strong lateral radiation leakage from an antiguide make them well suited for array integration. Antiguided VCSELs have been demonstrated by either the regrowth of high-index material in a buried heterostructure design, 7 selective oxidation, 8 or by a cavity-induced resonant shifted structure. 9 Serkland et al. 10 have recently demonstrated leaky-wave coupling between two antiguided VCSELs ͑coupled in-phase or out-of-phase͒ using structures fabricated with a cavity-induced resonance shift. Here we demonstrate that 2D ͑4ϫ4͒ VCSEL arrays can be designed to operate in a stable in-phase mode in good agreement with theory. Calculations show resonant coupling 6 for the inphase ͑out-of-phase͒ mode occurs when the interelement spacing corresponds to an odd ͑even͒ integral number of half-waves of the antiguide radiation leakage, and that the use of interelement loss can be effective in suppressing nonresonant modes.For simplicity, we studied the leaky modes of a 4ϫ4 antiguided VCSEL array structure using a fiber-mode effective-index approximation. 11 These structures support leaky modes with the elements phase-locked i...

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Two-dimensional phase-locked arrays of vertical-cavity semiconductor lasers by mirror reflectivity modulation

Cited by 118 publications

References 6 publications

Large Coherence Area Thin-Film Photonic Stop-Band Lasers

Large Coherence Area Thin-Film Photonic Stop-Band Lasers

Modal properties of two-dimensional antiguided vertical-cavity surface-emitting laser arrays

Two-dimensional phase-locked antiguided vertical-cavity surface-emitting laser arrays

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