Two-dimensional Photonic Crystal Lasers Research Articles

High-Q two-dimensional perovskite topological laser.

Quasi-two-dimensional perovskites have attracted widespread interest in developing low-cost high-quality small lasers. The nano cavity based on topologically protected valley edge states can be robust against special defects. Here, we report a high-quality two-dimensional perovskite topological photonic crystal laser based on the quantum valley Hall effect. By adjusting the position of the air holes relative to the pillar, radiation leakage in topological edge states is reduced to a large extent, electric field distribution becomes more uniform and the quality factor can be as high as 3.6 × 104. Our findings could provide opportunities for the development of high-power, stable perovskite lasers with topological protection.

Advanced dry etching of GaAs/AlGaAs multilayer wafer with InAs quantum dot for circular defect in photonic crystal laser

We previously proposed the circular defect in two-dimensional photonic crystal (CirD) laser based on a GaAs/AlGaAs multilayer wafer, which is fabricated by dry etching. This CirD laser uses InAs quantum dot (QD) layers as the gain medium, but this inhibits vertical dry etching. We improved the dry etching process by introducing three QD layers and three-step dry etching for fabricating the CirD laser. As a result, CirD structures with good etching profiles could be fabricated and excellent optical properties were obtained. We observed lasing by a CirD laser fabricated by deep etching under photoexcitation measurement for the first time.

Investigating wavelength bandwidth of orthogonal lattice waveguide for circular defect in two-dimensional photonic crystal (CirD) lasers

To achieve wavelength division multiplexing of optical communications for short distances, we have theoretically investigated a photonic crystal waveguide we call an orthogonal lattice waveguide (OLW), which may have a communication wavelength bandwidth of about 20 nm. In this paper, we fabricate CirD laser structures with air-cladding layers and OLWs of different cavity radii. We confirm that the light emitted from the OLW is the light generated in the cavity. OLW has a wavelength bandwidth of about 20 nm, which agrees with the results of our previous theoretical study. The wavelength shift is about 4 nm when the radius of the circular defect cavity increases by 0.01 a, where a is the lattice constant.

Two-dimensional photonic crystal Bragg lasers with triangular lattice for monolithic coherent beam combining

We demonstrate an electrically pumped, single-mode, large area, edge-emitting InGaAsP/InP two-dimensional photonic crystal (PC) Bragg laser with triangular lattice. The laser operates in the single transverse and longitudinal modes with a single lobe, near-diffraction-limited far field. We compare the performance of the triangular-lattice PC Bragg laser with the rectangular-lattice PC Bragg laser fabricated from the same wafer and find that their performances are comparable. Then, we combine two single triangular-lattice PC Bragg lasers that tilt to opposite directions by taking advantage of the symmetry of the single emitter cavity mode. The measurement results show that the combined PC Bragg lasers provide the near-diffraction-limited output beam, and the single wavelength operation is also maintained in the coherently combined broad-area PC Bragg lasers.

Two-dimensional photonic crystal bandedge laser with hybrid perovskite thin film for optical gain

We report optically pumped room temperature single mode laser that contains a thin film of hybrid perovskite, an emerging photonic material, as gain medium. Two-dimensional square lattice photonic crystal (PhC) backbone structure enables single mode laser operation via a photonic bandedge mode, while a thin film of methyl-ammonium lead iodide (CH3NH3PbI3) spin-coated atop provides optical gain for lasing. Two kinds of bandedge modes, Γ and M, are employed, and both devices laser in single mode at similar laser thresholds of ∼200 μJ/cm2 in pulse energy density. Polarization dependence measurements reveal a clear difference between the two kinds of bandedge lasers: isotropic for the Γ-point laser and highly anisotropic for the M-point laser. These observations are consistent with expected modal properties, confirming that the lasing actions indeed originate from the corresponding PhC bandedge modes.

Lasing action in strongly coupled plasmonic nanocavity arrays

Periodic dielectric structures are typically integrated with a planar waveguide to create photonic band-edge modes for feedback in one-dimensional distributed feedback lasers and two-dimensional photonic-crystal lasers. Although photonic band-edge lasers are widely used in optics and biological applications, drawbacks include low modulation speeds and diffraction-limited mode confinement. In contrast, plasmonic nanolasers can support ultrafast dynamics and ultrasmall mode volumes. However, because of the large momentum mismatch between their nanolocalized lasing fields and free-space light, they suffer from large radiative losses and lack beam directionality. Here, we report lasing action from band-edge lattice plasmons in arrays of plasmonic nanocavities in a homogeneous dielectric environment. We find that optically pumped, two-dimensional arrays of plasmonic Au or Ag nanoparticles surrounded by an organic gain medium show directional beam emission (divergence angle <1.5° and linewidth <1.3nm) characteristic of lasing action in the far-field, and behave as arrays of nanoscale light sources in the near-field. Using a semi-quantum electromagnetic approach to simulate the active optical responses, we show that lasing is achieved through stimulated energy transfer from the gain to the band-edge lattice plasmons in the deep subwavelength vicinity of the individual nanoparticles. Using femtosecond-transient absorption spectroscopy, we verified that lattice plasmons in plasmonic nanoparticle arrays could reach a 200-fold enhancement of the spontaneous emission rate of the dye because of their large local density of optical states.

Lasing in nanoimprinted two-dimensional photonic crystal band-edge lasers

We demonstrate optically pumped polymer band-edge lasers based on a two-dimensional photonic crystal slab fabricated by nanoimprint lithography (NIL). Lasing was obtained at the photonic band-edge, where the light exhibits a low group velocity at the Γ point of the triangular lattice photonic crystal band structure. The active medium was composed of a dye chromophore-loaded polymer matrix directly patterned in a single step by nanoimprint lithography. Plane-wave and finite difference time domain algorithms were used to predict experimental lasing frequencies and the lasing thresholds obtained at different Γ points. A low laser threshold of 3 μJ/mm2 was achieved in a defect-free photonic crystal thus showing the suitability of nanoimprint lithography to produce cost-efficient optically pumped lasers.

Fabrication of two dimensional high aspect ratio polymer photonic crystal laser

Photonic crystals have attracted much attention from researchers because of the control over the propagation and emission of light and particular optical properties. In this paper, we reported on the design, fabrication and test of a two-dimensional polymer photonic crystal laser. First of all, a two-dimensional polymer photonic crystal laser with a triangle-lattice structure was described. Rhodamine 6G doped in PMMA was chosen as the gain material. Then, plane wave method based on the Maxwell equations was utilized to calculate the distribution of the photonic band gap. We calculated the band structure of a triangle lattice photonic crystal with a low refractive index. High resolution electron beam lithography combined with electroplating was used to fabricate the silicon nitride mask. A high aspect ratio two-dimensional photonic crystal laser was fabricated by X-ray lithography in one-step process to overcome the limitation of the thickness by the conventional methods to realize a real two-dimensional laser. Meanwhile, processes of sample preparations and fabrication were optimized in order to avoid the oxidation of the gain material and reduce the diffraction effect on the structures.

Parity Anomaly and Landau-Level Lasing in Strained Photonic Honeycomb Lattices

We describe the formation of highly degenerate, Landau-level-like amplified states in a strained photonic honeycomb lattice in which amplification breaks the sublattice symmetry. As a consequence of the parity anomaly, the zeroth Landau level is localized on a single sublattice and possesses an enhanced or reduced amplification rate. The selection of the sublattice depends on the strain orientation but is independent of the valley. The spectral properties of the higher Landau levels are constrained by a generalized time-reversal symmetry. In the setting of two-dimensional photonic crystal lasers, the anomaly affects the mode selection and lasing threshold while in three-dimensional photonic lattices it can be probed via the beam dynamics.

Effects of non-lasing band in two-dimensional photonic-crystal lasers clarified using omnidirectional band structure

We investigated the effects of non-lasing bands on the beam patterns in photonic-crystal lasers by evaluating the omnidirectional band structure both experimentally and theoretically. We found that a new, weak dual-streak pattern is occasionally generated around the main lobe of the output beam because of scattering of the lasing beam in the non-lasing bands despite a wavenumber mismatch. This result indicates that we can design the high-quality devices without such a noise pattern. In addition, this evaluation method is expected to be useful for developing various high-functionality PC lasers.

Optically pumped lasing from organic two-dimensional planar photonic crystal microcavity

In this letter, we report the realization and characterization of a planar two-dimensional organic photonic crystal microcavity laser. The gain medium consists of a tris(8-hydroxyquinolinato) aluminum doped with 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran and is deposited on a lithographically patterned silicon nitride two dimensional photonic crystal H2 microcavity. The experimental results show a laser emission at 662 nm with a threshold of 9.7 μJ/cm2.

All-organic two-dimensional photonic crystal laser based on holographic polymer dispersed liquid crystals

In this paper, we report a kind of dye-doped two-dimensional photonic crystal based on holographic polymer dispersed liquid crystals (HPDLC) with a lattice constant of 582nm, which is prepared conveniently with a single step holographic exposure. Under the excitation of a frequency-doubled Nd:yttrium-aluminum-garnet laser operating at a wavelength of 532nm, optically pumped lasing with narrow bandwidth and low threshold is observed from a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye-doped two-dimensional photonic crystal. The results show that the emitted lasing peak is centered at about 603nm with a full width at half maximum of only 0.4nm, and the threshold energy is about 22.7 J, which is evidently lower than the reported previously. The laser bandwidth decreases by a factor of three from 1.4nm to 0.4nm compared with that of the dye-doped HPDLC transmission grating. This result exhibits a bright prospect in application of tunable photonic crystal laser.

Band optimization of two-dimensional photonic crystal surface-emitting laser

The three-dimensional (3D) plane wave expansion method with supercell approximationhas been employed to investigate in detail the band structure of the two-dimensionalphotonic crystal (PhC) surface-emitting laser with square lattice. The symmetricpoint band structure has been calculated to obtain the optimized structures ofPhC surface-emitting lasers. There exists a range of parameter pairs, includingperiods and area-filling factors of the PhC, which can create an in-plane stopband at the high frequency side of the monopole mode at the second order of theΓ-point(Γ2- 1) in each structure. This in-plane stop band isolatesΓ2- 1 from the unwanted band edge modes, inhibits the spontaneous emission at the high frequency sideof Γ2- 1, makes the device achieve single band edge mode lasing oscillation and improves theperformance of the PhC surface-emitting laser. The resonant spectra, quality factors andoutput efficiencies have been calculated by the 3D finite-difference time-domain method toverify the band optimization, which provides important guidelines for device design andfabrication.

Mode analysis of two-dimensional photonic crystal terahertz lasers with gain/loss dispersion characteristics

Gain/loss dispersion characteristics of photonic modes in a two-dimensional photonic crystal (PC) are demonstrated for the first time, to our knowledge. The dispersion analysis is based on an improved plane-wave expansion method that includes the gain/loss factor along the propagation direction of each plane wave and treats surface-emission properties. PC lasers operating at terahertz frequency are considered for the numerical calculation. Our analysis indicates that although PC lasers with different lattice periods possess almost the same photonic band structure, their gain/loss dispersion characteristics are significantly different. The systematic study on gain/loss dispersion characteristics reveals the optimum PC structure to obtain high-performance surface-emitting lasers.

120 μ W peak output power from edge-emitting photonic crystal double-heterostructure nanocavity lasers

As an attempt to collect more in-plane emission power out of wavelength size two-dimensional photonic crystal defect lasers, edge-emitting photonic crystal double-heterostructure quantum well membrane lasers were fabricated by shortening the number of cladding periods on one side. 120μW peak output power was collected from the facet of the single mode laser at room temperature. Laser efficiencies were analyzed and agree very well with three-dimensional finite-difference time-domain modeling.

GaN-based two-dimensional surface-emitting photonic crystal lasers with AlN∕GaN distributed Bragg reflector

GaN-based two-dimensional (2D) surface-emitting photonic crystal (PC) lasers with AlN∕GaN distributed Bragg reflectors are fabricated and demonstrated. The lasing threshold energy density is about 3.5mJ∕cm2 per pulse under optical pumping at room temperature. Only one dominant emission wavelength of 424.3nm with a narrow linewidth of 1.1Å above the threshold is observed. The laser emission covers whole circularly 2D PC patterns (50μm in diameter) with a small divergence angle. The lasing wavelength emitted from 2D PC lasers with different lattice constants occurs at the calculated band-edges provided by the PC patterns. The characteristics of large area, small divergence angle, and single mode emission from the GaN-based 2D surface-emitting PC lasers should be promising in high power blue-violet emitter applications.

Two-dimensional polymer photonic crystal band-edge lasers fabricated by nanoimprint lithography

We report on the fabrication and characterization of two-dimensional polymer photonic crystal band-edge lasers operating in the visible range. The components have been fabricated in a dye chromophore-loaded polymer matrix by nanoimprint lithography. High-symmetry band-edge modes are used to generate laser emission. The experimental lasing frequencies are in good agreement with those calculated using a two-dimensional plane wave algorithm. These results demonstrate the potential of nanoimprint lithography for the fabrication of two-dimensional planar photonic crystal structures in an active medium in a one-step process.

Spatial modal control of two-dimensional photonic crystal Bragg lasers

We investigate the modal losses and field distributions of different order transverse modes supported by the photonic crystal Bragg structure using a transfer matrix method. We find that only the fundamental transverse mode has a single-lobed near field and far field and there exists a trade-off between ensuring lasing in the fundamental transverse mode and reducing the threshold. Employing these design principles, we experimentally demonstrate a large-area, edge-emitting, and single-mode semiconductor photonic crystal Bragg laser with a single-lobed, diffraction-limited far field under continuous wave condition.

Laser nanosources based on planar photonic crystals as new platforms for nanophotonic devices

Two-dimensional photonic crystal lasers have been fabricated on III–V semiconductor slabs. Tuning of the spontaneous emission in micro and nanocavities has been achieved by accurate control of the slab thickness. Different structures, some of them of new application to photonic crystal lasers, have been fabricated like the Suzuki-phase or the coupled-cavity ring-like resonators. Laser emission has been obtained by pulsed optical pumping. Optical characterization of the lasing modes have been performed showing one or more laser peaks centred around 1.55 μm. Far field characterization of the emission pattern has been realized showing different patterns depending on the geometrical shape of the structures. These kinds of devices may be used as efficient nanolaser sources for optical communications or optical sensors.

Laser Diode-Pumped Organic Semiconductor Lasers Utilizing Two-Dimensional Photonic Crystal Resonators

Two-dimensional photonic crystal lasers based on the small molecule organic semiconductor tris-(8-hydroxyquinoline) aluminum (Alq <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) doped with 4-Dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) are optically pumped with a conventional low-cost pulsed (In)GaN laser diode. We compare photonic crystal resonators providing first- and second-order distributed feedback and find threshold values of 1.9 and 3.2kW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , respectively. Such inorganic-organic hybrid laser systems open up a way to inexpensive, tunable, and all solid-state lasers in the full visible wavelength range