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Electrically injected photonic crystal membrane light emitting microcavities with spatially localized optical gain are reported. The localization of the InGaAs quantum well inside the defect cavity of the photonic crystal allows for efficient coupling of the optical mode to the gain medium and reduces nonradiative carrier recombination. The use of a buried oxide layer under the semiconductor membrane enables optical and electrical confinement and a submicron diameter oxide aperture provides a current path. Enhancement of the electroluminescence intensity is observed as a result of the spatial localization of the quantum well, and the spectral characteristics at room temperature indicate the photonic crystal microcavity confinement. [ABSTRACT FROM AUTHOR]

Using nonlinear programing and the geometry projection method, the quality factor of the monopole mode of a single defect photonic crystal laser cavity is improved from 38 000 to 87 000. Beginning with a design that considers only round air holes shifted away from the cavity, the radius of the nearest neighbor and of the surrounding air holes are optimized while satisfying a constraint on the resonant frequency. The total reflectivity of the photonic crystal laser structure is then defined, and it is shown that this quantity correlates strongly to the total quality factor. The reflectivity of the structure is improved by altering the shape of the holes immediately surrounding the cavity, thus leading to an improvement in quality factor. The geometry projection method is used to define the shape of the holes and the finite element and adjoint methods are used to compute the objective function and sensitivities required by the optimizer. This work demonstrates one way to optimize the Q factor of a photonic crystal laser by altering the hole shape. [ABSTRACT FROM AUTHOR]

We report polarization characteristics of light from a photonic quantum ring (PQR) laser of three-dimensional (3D) whispering gallery modes. The 3D polarization states of light from the PQR laser were studied with a home-built solid-angle scanner capable of detecting the spatial intensity distribution in a wide range of solid angles. The analysis shows that the dominant polarization vectors of the PQR laser emitting in the surface normal direction lie always tangential to the PQR perimeter, which means there is a strong carrier-photon coupling. [ABSTRACT FROM AUTHOR]

Photonic wire lasers are compact light sources that are fabricated in high-index contrast waveguides (with typical widths of a few hundreds of nanometers). Because of their small footprints, they may become a basic laser component in future-generation of optical integrated circuits. Owing to having low optical volume by design, photonic wire lasers can only produce low output power that may not be adequate in many applications. A solution to this problem is to coherently combine the output power of different photonic wire lasers to produce larger output power. In this article, we analyze different ways to combine light coming out from photonic wire lasers and couple the combined power into a single-mode waveguide. [ABSTRACT FROM AUTHOR]

It is shown that two-dimensional (2D) Bragg resonance structures can be used for the synchronization of emission from a spatially developed laser active medium. Analysis of the dynamics of a laser with 2D distributed feedback shows that stationary lasing with a frequency and a spatial structure of the field close to the fundamental mode of a 2D Bragg resonator is possible in the structures with large values of the Fresnel parameter. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the coupling of light from photonic-crystal band-edge lasers into single-mode waveguides. Both active and passive devices lie in the same plane and coupling of light is achieved by using parabolic and nanotapers in InP based epitaxial structures. Two- and three-dimensional finite-difference time-domain methods are employed to analyze these devices. Coupling efficiencies higher than 80% can be obtained with parabolic couplers. We also present laser configurations that can reduce multiwavelength coupling of light into single-mode waveguides, using structures that are similar to coupled cavity Fabry-Pérot lasers. [ABSTRACT FROM AUTHOR]

We demonstrate mom-temperature low-threshold- current lasing action from electrically driven wavelength-scale high-quality photonic crystal lasers having large spontaneous emission factors by solving the theoretical and technical constraints laid upon by the additional requirement of the current injection. The ultrasmall cavity is electrically pulse pumped through a submicron-size semiconductor "wire" at the center of the mode with minimal degradation of the quality factor. In addition, to better utilize the low mobifity of the hole, we employ a doping structure that is inverted from the conventional semiconductors. Rich lasing actions and their various characteristics are experimentally measured in the single-cell and three-cell photonic crystal cavities. Several relevant measurements are compared with three-dimensional finite-difference time-domain computations based on the actual fabricated structural parameters. The electrically driven photonic crystal laser, which is a small step toward a "practical" form of the single photon source, represents a meaningful achievement in the field of photonic crystal devices and photonic integrated circuits as well as of great interest to the quantum electrodynamics and quantum information communities. [ABSTRACT FROM AUTHOR]

We report the development of a tunable photonic crystal coupled-cavity laser diode based on InP. The laser consists of two photonic crystal channel waveguides that are coupled through a photonic crystal mirror segment in ΛM direction. The cavity lengths define the respective mode spacings in the cavities. The tuning characteristics of the device are compared with results obtained from a transfer matrix model. Quasi-continuous tuning is achieved in a 29.6-nm window with 36 wavelength division multiplexing channels spaced 0.8 nm apart (ITU grid). The simplicity of fabrication and promising output characteristics should make this tunable laser design an interesting source for monolithic integration into highly integrated photonic circuits. [ABSTRACT FROM AUTHOR]

We report results on hexagonal-shaped microlasers formed from two-dimensional photonic crystals (PCs) using InP-based materials transferred and bonded onto SiO[sub 2]/Si wafers. Two types of hexagonal cavities are investigated: single detect (one hole missing) cavities, so-called H1 cavities (1 μm in diameter) and two holes missing per side H2 cavities (2 μm in diameter). Their optical properties are analyzed using photoluminescence experiments, and plane wave method simulations have been performed for comparison. High Q modes (∼ 600/700) have been measured and they have been shown to enable laser effect at room temperature, under pulsed optical pumping (15% duty cycle and 25-ns pulsewidth). The study of these efficient mode characteristics gives guidance for further improvement of the operation conditions of PC lasers, such as the reduction of the threshold pumping power. [ABSTRACT FROM AUTHOR]

Investigates the far-field emission patterns and near-field intensity distribution of the lasing modes in two-dimensional (2-D) photonic crystal slab lasers. Analysis in polarization-resolved 2-D angular distribution; Identification of various lasing modes; Manifestation of transverse-electric in one-dimensional modes.

Investigates on the threshold gain and single-mode oscillation of photonic defect lasers. Behavior of defect laser of various parameters; Presence of multi-mode oscillation with a large defect radius; Prediction of single-mode oscillation and small threshold gain; Use of device parameters; Reduction of defect refractive index.

Focuses on the existence of high Q whispering galley modes in microdisk and microcylinder lasers that affects the internal efficiency in lasing operations. Use of the finite-difference time-domain simulation method; Proposed microgear cavity having a grating with the same period as that of the mode standing wave; Structural parameters that affect dependence of the mode behavior.

A GaInAsP photonic crystal nanolaser was operated by resonant optical pumping in which the effective cavity area was selectively excited. The laser mode intensity was markedly enhanced when the pump wavelength was tuned to a higher-order cavity mode, and room-temperature continuous-wave lasing was obtained in the fundamental mode. Furthermore, the switching behavior due to a modal wavelength shift was clearly observed, suggesting the possibility of bistable operation, and so on. [ABSTRACT FROM AUTHOR]

We recently reported room-temperature continuous-wave operation in a GaInAsP photonic crystal slab nanolaser. In this letter, we demonstrate effective light extraction from the nanolaser monolithically integrated with a passive waveguide by using a GaInAsP butt-joint regrowth technique. Theoretically, the extraction efficiency through the waveguide was calculated to be 80% for the optimum design of the coupling system of the nanolaser and the waveguide. In the experiment, we evaluated a differential quantum efficiency of 4%, which was degraded mainly due to the detection loss of the output light. [ABSTRACT FROM AUTHOR]

The authors report an electrically driven, hexapole mode, single-cell photonic crystal laser operating at 1537.8 nm. Electrical current is supplied through a submicrometer-sized current post beneath the cavity center. This wavelength-scale single-cell photonic crystal laser operates in a single mode with threshold current of ∼100 μA at room temperature. Operation in the hexapole mode is confirmed by the near-field profile, far-field polarization, and the finite-difference time-domain computation based on the fabricated cavity structure. [ABSTRACT FROM AUTHOR]

We recently reported the laser operation of a nanocavity consisting only of a shift in two of the lattice points in a GaInAsP photonic crystal slab. In this study, we investigated the laser characteristics in detail. For lithographic tuning, three different modes were observed, and good agreement between the experimental results and theoretical calculations performed using the finite-difference time-domain method was obtained. These results suggest that the fundamental mode has a modal volume of 0.02 μm3∼2.1(λ/2n)3, which is the smallest in any kind of laser. Such an ultrasmall modal volume will ensure efficient electron-photon coupling. [ABSTRACT FROM AUTHOR]

We propose and report an encapsulated photonic crystal concept for efficient electrical injection of photonic crystal surface-emitting lasers. Detailed rate equation analysis reveals a significant threshold current reduction by minimizing the surface-state-induced carrier loss. The impact of encapsulation on the photonic band gap is discussed for different encapsulation conditions. Experimental results on encapsulation process are reported, based on nanoparticle self-assembly. [ABSTRACT FROM AUTHOR]

We realize an active two-dimensional (2D) photonic crystal laser with a combination of line defects and point defects. Based on a line-defect–waveguide laser in a 2D photonic crystal slab, we observe laser emission from the point defect at the waveguide mode-edge frequency when there is a frequency mismatch with the point-defect mode. This phenomenon is due to the wide-field distribution at the waveguide mode edge and its distortion by the adjacent point defect. Numerical calculations estimate the emission efficiency and are in good agreement with experimental results. [ABSTRACT FROM AUTHOR]

Here we investigate a line-defect-waveguide laser in a two-dimensional photonic-crystal slab. The change δλ in lasing wavelength for a change δW in waveguide width is found to be extremely large: δλ/δW = 2. It is two orders of magnitude greater than that for a conventional distributed-feedback laser. An investigation of the electromagnetic-field distribution at the waveguide-mode edge is made, giving an indication of the cavity-mode structure for lasing oscillation. Fourier transform analysis reveals that the extremely large tenability originates from the ‘zigzag’ mode behavior of the line-defect waveguide in the photonic crystal, due to two-dimensional distributed feedback and reflection. [ABSTRACT FROM AUTHOR]

We fabricated a 12-fold symmetric quasiperiodic photonic crystal (QPC) point defect laser, and obtained the lasing action at room temperature. When photopumping a seven-hole-missing defect or a uniform QPC part, the lasing occurred by different modes. The finite-difference time-domain analysis showed that the defect mode is a whispering gallery mode, which is confined by the photonic gap or the boundary reflection. It also indicated that the defect-free mode is an extended but partly localized mode, which cannot be seen in photonic crystals. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We observed modulated oscillations in lasers of up to 130 GHz by conducting frequency domain measurements on photonic crystal lasers with built-in saturable absorbers. This is an example of how the small volumes of photonic crystal lasers lead to increases in the internal modulation frequencies and enables dramatic improvements of the laser modulation rate. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

1.55-μm-InGaAsP photonic crystal lasers operating in the monopole mode of a triangular lattice defect cavity are realized by room-temperature optical pumping with a low threshold of <0.5 mW. By analyzing rate equations and the light–light characteristic curve, we evaluate the spontaneous emission factor (β) of this laser to be larger than 0.1, an extremely high value for photonic crystal lasers. The achievement of this large β is attributed to the facts that the investigated monopole-mode laser operates at the peak of the spontaneous emission spectrum and it shows a single-mode operation in a wide spectral range. In addition, nonclamping of carrier density near threshold and the β>0.1 are confirmed by the investigation of carrier-density dependent wavelength blueshift of the lasing mode. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Few-micron-sized elliptically deformed InGaAsP–InP microdisk lasers are fabricated and highly directional emissions are observed along the direction perpendicular to the surface of highest curvature. As the size of the elliptical microdisk is reduced, both the azimuthal angular spreading and the number of lobes become smaller. The improved directionality of the smaller structure is attributed to the enhanced tunneling loss at the high curvature surfaces. The far-field radiation is linearly polarized. Charge-coupled-device images confirmed the existence of strong near-field emission in the vicinity of high curvature surfaces. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Square-lattice bandedge lasers are realized by room-temperature optical pumping of photonic crystal air-bridge slabs of InGaAsP quantum wells emitting at 1.5 μm. Lasing modes corresponding to the second bandedges near the X and M points are identified from their spectral positions and polarization directions. A low threshold incident pump power of less than 1 mW is achieved for the laser operating at the second bandedge near the X and M points, with only 15×15 lattice points. The measured characteristics of the bandedge lasers closely agree with the result of calculations based on the plane-wave-expansion method and the finite-difference time-domain method. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have realized photonic crystal lasers that permit the introduction of analyte within the peak of the optical field of the lasing mode. We have explored the design compromises for developing such sensitive low-threshold spectroscopy sources, and demonstrate the operation of photonic crystal lasers in different ambient organic solutions. We show that nanocavity lasers can be used to perform spectroscopic tests on femtoliter volumes of analyte, and propose to use these lasers for high-resolution spectroscopy with single-molecule sensitivity. [ABSTRACT FROM AUTHOR]

Operation of photonic crystal lasers for substrate temperatures as high as 50 °C is reported. The temperature dependence of the lasing wavelength and the threshold pump power is also investigated. The characteristic temperature T[SUBo] is 37.7 K. [ABSTRACT FROM AUTHOR]

We have fabricated photonic crystal nanocavity lasers, based on a high-quality factor design that incorporates fractional edge dislocations. Lasers with InGaAsP quantum well active material emitting at 1550 nm were optically pumped with 10 ns pulses, and lased at threshold pumping powers below 220 μW, the lowest reported for quantum-well based photonic crystal lasers, to our knowledge. Polarization characteristics and lithographic tuning properties were found to be in excellent agreement with theoretical predictions. [ABSTRACT FROM AUTHOR]

Square-lattice photonic band-gap lasers are realized at room temperature from single-cell photonic crystal slab microcavities fabricated in InGaAsP quantum-well materials emitting at 1.5 µm. This single-cell photonic band-gap laser operates in a class of two-dimensional mode to be classified as the smallest possible whispering gallery mode with genuine energy null at the center. The low-loss nondegenerate mode with modal volume of 0.1 (λ/2)³ demonstrates a spectrometer-limited below-threshold quality factor >2000 and a theoretical quality factor > 10 000. The other class of photonic crystal lasers is also observed outside the photonic band gap of the square lattice, operating in the dipole mode. [ABSTRACT FROM AUTHOR]

Photonic band-edge lasers are realized in the free-standing triangular photonic crystal slab with InGaAsP quantum wells at 80 K. Surface-emitting lasing actions are observed from the samples whose wavelengths correspond to the second or the third photonic band edge near the Γ point of the band structure, which is confirmed by the three-dimensional finite-different time-domain calculation. A very low threshold of 35 μW (incident pump power) is achieved from the laser operating near the third transverse-electric-mode band edge. This low threshold is benefited from low optical losses near the Γ point as well as reduced surface recombination carrier losses and enhanced material gain at low temperature. It is interesting to note that this two-dimensional distributed feedback lasing action is observed from a surprisingly small pump area of 6 μm in diameter. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We propose and demonstrate photonic band gap lasing action from a nondegenerate monopole-mode, high-quality factor cavity. By optical pumping at room temperature, the monopole-mode laser is realized and identified from its mode shape, spectrum, and polarization. The monopole-mode laser shows nondegeneracy and genuine two-dimensional oscillation with incident threshold pump power less than 0.3 mW. This laser mode has a small modal volume of ∼4.5(λ/2n[sub slab])[sup 3] and shows a quality factor of larger than 1900, estimated from the spectral linewidth below threshold. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Examines the anomalous above-threshold spontaneous emission in gain-guided vertical-cavity surface-emitting lasers (VCSEL). Origin of VCSEL spontaneous emission; Impact of constant modal gain on average carrier density; Occurrence of nontrivial errors for external quantum efficiency determination.