Optical injection locking of 1.3-µm phase-locked VCSEL arrays defined by patterned tunnel junctions and wafer fusion is investigated experimentally and theoretically. The impact of the overlap between the master laser injection beam and the injected modes is demonstrated and explained with a rate equation model that incorporates the spatial variations.

The polarization of the beam emitted from long-wavelength VCSELs is characterized with the Stokes parameters. Stable optical modes are discovered, with a polarization that differs from the linear case. Results are explained by hybridization of the VCSEL modes and a negative line width enhancement factor.

We report on transverse mode discrimination in long-wavelength wafer-fused vertical-cavity surface-emitting lasers (VCSELs) incorporating ring-shaped air gap patterns at the fused interface between the active region and the top distributed Bragg reflector (DBR). These 60-nm deep patterns were implemented with the aim of favoring the fundamental mode while preserving high output power. The VCSELs under consideration emit in the 1310-nm band and incorporate an AlGaInAs-based quantum well active region, a regrown circular tunnel junction and undoped GaAs/AlGaAs DBRs. A large batch of devices with varying pattern dimensions was investigated by on-wafer mapping, allowing significant statistical analysis leading to conclusions on their typical behavior. We observe experimentally a dependence of the side-mode suppression ratio on the geometrical parameters of the patterns. In particular, we identified a design that statistically increases the maximal single-mode emitted power by more than 20%. Numerical simulations of the patterned-cavity VCSELs based on our fully three dimensional electrical, thermal and optical VCSEL computational model support these observations. They show that patterns with a large inner diameter actually confine the first-order transverse mode and enhance its modal gain. In smaller devices, this mode is pushed out of the optical aperture and suffers larger losses. Optimized parameters were found numerically for enhancing the single-mode properties of the devices with negligible penalty on emitted power and threshold current.

Transverse mode discrimination is demonstrated in long-wavelength wafer-fused vertical-cavity surface-emitting lasers using ring-shaped air gap patterns at the fused interface between the cavity and the top distributed Bragg reflector. A significant number of devices with varying pattern dimensions was investigated by on-wafer mapping, allowing in particular the identification of a design that reproducibly increases the maximal single-mode emitted power by about 30 %. Numerical simulations support these observations and allow specifying optimized ring dimensions for which higher-order transverse modes are localized out of the optical aperture. These simulations predict further enhancement of the single-mode properties of the devices with negligible penalty on threshold current and emitted power.

We report coupled VCSEL arrays, emitting at 1.3 μm wavelength, in which both the optical gain/loss and refractive index distributions were defined on different vertical layers. The arrays were electrically pumped through a patterned tunnel junction, whereas the array pixels were realized by intra-cavity patterning using sub-wavelength air gaps. Stable oscillations in coupled modes were evidenced for 2x2 array structures, from threshold current up to thermal roll-over, using spectrally resolved field pattern analysis.

Mode control in wafer-fused 1.3 mu m wavelength coupled-VCSEL arrays is achieved by cavity structuring and investigated by spectrally resolved near- and far-field measurements. Improved mode discrimination is attained by combining index- and gain-patterning. (C)2010 Optical Society of America

Spatial transverse modes and polarization states are experimentally studied in single vertical cavity surface emitting lasers (VCSELs) and phased-locked VCSEL arrays emitting at 1.3μm wavelength. Analysis of the polarization-resolved near fields, far fields and emission spectra permit the observation of the competition between the different modes. Possible ways for increasing single mode power and spectral purity are discussed.

Using tunnel junction patterning and double wafer fusion, we demonstrate phase-locked arrays of VCSELs emitting at the 1300 nm waveband. CW powers as high as 10 mW and coherent beams are demonstrated for various array configurations.

Vertical cavity surface emitting lasers (VCSEL) are already used in many applications thanks to their unique device characteristics, particularly compact size, low power consumption, accurate wavelength setting, circular beams and on-wafer testing. The main disadvantage of VCSELs as compared to edge emitting lasers is the relatively low single mode output power (a few milliwatts) limited by their small active area. To overcome this limitation, phase-locked arrays of short wavelength (≪ 1 µm) VCSELs have been investigated using different fabrication approaches [1]. Here, we report the fabrication and lasing characteristics of phase-locked 1300 nm wavelength VCSEL arrays made using double wafer fusion.

We report the fabrication and the performance of phase-locked VCSEL arrays emitting near 1310 nm wavelength. The arrays were fabricated using double wafer fusion by patterning a tunnel junction layer, which serves to define the individual single mode array elements. Phase-locking in both one-dimensional and two-dimensional array configurations was confirmed by means of far field and spectral measurements as well as theoretical modeling. CW output powers of more than 12 mW were achieved.

We report the fabrication and the performance of phase-locked VCSEL arrays emitting near 1310 nm wavelength. The arrays were fabricated using double wafer fusion by patterning a tunnel junction layer, which serves to define the individual single mode array elements. Phase-locking in both one-dimensional and two-dimensional array configurations was confirmed by means of far field and spectral measurements as well as theoretical modeling. CW output powers of more than 12 mW were achieved.

We report on the extremely large nonresonant quadratic optical nonlinearity of the stilbazolium salt trans-4'-(dimethylamino)-N-phenyl-4-stilbazolium hexafluorophosphate (DAPSH). The phenyl-pyridinium chromophores in DAPSH crystals grown from acetone solution pack with a highly aligned polar order, resulting in a very large birefringence, Delta n = 1.17 +/- 0.06 at lambda = 0.83 mu m and Delta n = 0.83 +/- 0.04 at lambda = 1.55 mu m. More importantly, this leads to an extremely large diagonal quadratic susceptibility with the nonlinear optical coefficient for second-harmonic generation reaching up to d(111) = 290 +/- 40 pm/V at 1.907 Am fundamental wavelength, which presents a considerable improvement with respect to the presently best material trans-4'-(dimethylamino)-N-methyl-4-stilbazolium tosyate (DAST) with d(111) = 210 +/- 55 pm/V at lambda = 1.907 mu m. The result is in agreement with the preferential packing of the chromophores and the previous studies demonstrating higher microscopic nonlinearity of the chromophores in DAPSH compared to that of DAST. (C) 2008 Optical Society of America

We report on the second harmonic generation of deep UV light in beta -BaB(2)O(4) (BBO) waveguides pumped by a frequency-doubled continuous-wave Nd:YAG laser. An output power of 0.32 mW at 266 nm has been achieved for an internal pump power of 670 mW. Optical channel waveguides in BBO crystals were produced by He(+) ion implantation, lithographic masking and ion etching. The linear and nonlinear optical properties and the power handling capability of these waveguides are presented.

We report on the electro-optic and nonlinear optical properties of waveguides produced by low fluence (Phi = 1.25x10(14) ions/cm(2)) H+ ion implantation in the organic nonlinear optic crystal 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST). The profile of the nonlinear optical susceptibility has been determined by measuring the reflected second-harmonic generation efficiency from a wedged-polished sample at a fundamental wavelength of lambda(omega) = 1176nm. In the waveguide core region the nonlinear optical susceptibility is shown to be preserved to more than 90% of its bulk value. A model which relates the molecular changes to the measured macroscopic alteration of the refractive index and the nonlinear coefficient has been introduced to quantify the fraction of molecules modified by ion implantation. Furthermore, a first electro-optic modulation in ion implanted DAST waveguides has been demonstrated.

We review the recent progress in the development of photonic applications based on the organic crystal 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST). DAST is an organic salt with an extremely high nonlinear optical susceptibility chi((2)) (-2 omega, omega, omega) = 580 +/- 30 pm/V at 1.54 mu m, a high electrooptic figure of merit n(3)r = 455 +/- 80 pm/V at 1.54 mu m, as well as a low dielectric constant epsilon = 5.2. DAST is, therefore, very attractive for high-speed optical modulators and field detectors, as well as for frequency conversion and the generation of terahertz waves. Several techniques to microscopically structure this material have been developed recently; including modified photolithography, photobleaching, femtosecond laser ablation, graphoepitaxial growth, ion implantation, and direct electron-beam structuring, which open new perspectives of using this exceptional material for high-speed very-large-scale integrated photonics.

New organic nonlinear optical configurationally locked polyene (CLP) crystals based on 3,5-dimethyl-2cyclohexen-1-one have been designed and their supramolecular organization investigated. Acentric single crystals 2-(5-methyl-3-(4-(pyrrolidin-1-yl)styryl)cyclohex-2-enylidene)malononitrile (MH2) of large sizes with a maximal side length of up to I cm have been grown from acetonitrile solution. The acentric MH2 crystals present the monoclinic space-group symmetry Cc and exhibit a large macroscopic nonlinearity with a similar powder second-harmonic generation efficiency at 1.9 mu m as the well-studied DAST (NN-dimethylaminoff-methylstilbazolium p-toluenesulfonate), which is about seven times larger than that of analogous CLP crystals studied previously. The microscopic and macroscopic nonlinearities are also investigated theoretically using quantum chemical calculations.

We report on a new, flexible, single-step technique to directly pattern electro-optically active channel waveguiding structures in the highly nonlinear optical organic crystal DAST using e-beam irradiation.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Results of the development of all metallorganic vapor-phase epitaxy (MOVPE) GaAs-based vertical cavity surface emitting lasers (VCSELs) with a regrown tunnel junction (TJ) emitting at similar to 1150-nm wavelength are presented. A zero-bias-specific resistance of similar to 3 x 10(-4) Omega cm(2) has been obtained for the GaAs-based TJ structure. VCSEL devices incorporating 4-7-mu m and 12-mu m TJ mesas exhibit an similar to 2-3 mA threshold current. Room-temperature lasing spectra are multimode with an output power of 1 and 2 mW, respectively, and thermal roll-over is above 25 mA. A 2 x 2 VCSEL array of 3-mu m aperture elements at 7-mu m pitch yielding 0.8 mW room-temperature output power has been realized. (c) 2008 Elsevier B.V. All rights reserved.

We report for the first time to our knowledge optical waveguiding in an organic crystalline waveguide produced by ion implantation. Using H+ ions a refractive index barrier suitable for waveguiding has been realized in the highly nonlinear optical organic crystal 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST). The refractive index changes in the waveguiding region as a function of the distance from the surface have been measured. Maximal refractive index changes of up to -0.2 and -0.1 at wavelengths of 633nm and 810nm have been realized, respectively. The waveguide refractive index profiles as a function of the ion fluence have been determined. Planar waveguiding has been demonstrated by polishing sharp edges and using conventional end-fire coupling. The measured losses are approximately 7 dB/cm at 1.57mum.