Photonic Quantum Ring Research Articles

Three-dimensional Characteristics of the Photonic Quantum Ring Laser

Three-dimensional Characteristics of the Photonic Quantum Ring Laser

Characterization of photonic quantum ring devices manufactured using wet etching process

Characterization of photonic quantum ring devices manufactured using wet etching process

A new spectroscopy based upon 3D photonic quantum ring lasers for non-invasive and portable brain/heart disease diagnostic techniques

A new spectroscopy based upon 3D photonic quantum ring lasers for non-invasive and portable brain/heart disease diagnostic techniques

Two-photon excited photoluminescence of photonic quantum ring laser structures

We report on the two-photon excited photoluminescence of photonic quantum ring laser structures using Ti:Sapphire femtosecond pulsed laser. Using two-photon excited photoluminescence microscopy, we were able to image the laser structures when optically excited and compare the results with previously obtained images on electrically pumped photonic quantum ring lasers. We also propose a method to evaluate the Rayleigh band on the circumference of these structures.

Optical beam induced current microscopy of photonic quantum ring lasers

A confocal laser scanning microscope modified to acquire optical beam induced current images is used to investigate a novel type of semiconductor lasers—photonic quantum ring lasers. We compare the lasing and the photoinduced current images of the structures and analyze their behavior when changing the excitation wavelength. We report the optimal excitation conditions in terms of excitation laser wavelength for collecting the highest photocurrent signal and hence highlighting the photonic quantum ring behavior of the lasers.

Spatiotemporal dynamics in Rayleigh band of photonic quantum ring laser

Spatiotemporal dynamic simulations are carried out for the carrier-field interactions of photonic quantum ring lasers of three dimensional (3D) whispering cave modes (WCMs). We observe quantum wires-like carrier re-distributions naturally formed in the Rayleigh band region of the active quantum well plane. Apart from the regular two dimensional (2D) whispering gallery mode (WGM), the 3D WCM’s major polarization state favors a strong carrier-photon coupling for the carriers in the Rayleigh band, such that the powerful transient coupling generates photonic quantum rings (PQRs), or concentric quantum rings with a half-wavelength pitch of imminently recombinant carriers, i.e., a photonic quantum corral effect. This feature is responsible for the low threshold currents and thermally stable spectra, which opens the way for easy optical mega-pixel (‘Omega’) chip fabrications.

Photonic quantum ring flower laser of whispering cave mode

A flower-type photonic quantum ring (PQR) laser for enhanced output power of about five times that expected from circular PQR lasers of the same size has been designed and fabricated. The multi-petal flower design, combining concave and convex whispering cave modes, increases the overall quantum wire length of the emitting PQR within the same device area.

Photonic quantum ring laser of 3D whispering cave mode

A new whispering cave mode (WCM), a three-dimensional (3D) case of Lord Rayleigh's 2D whispering gallery modes, based upon 3D total internal reflection is presented, where GaAs quantum well (QW) near-vertical microdisk resonators exhibit a strong carrier–photon coupling for the QW carriers located in the Rayleigh band, generating 2D-to-1D carrier phase transitions of photonic quantum ring (PQR). It is a ‘photonic’ quantum corral effect (PQCE), whose simulation work produces a tangled web pattern of imminent recombinant carriers in picoseconds timescale. The PQCE is responsible for the ultralow threshold currents below 300nA for a single mode GaAs PQR laser, and a prototype GaN PQR laser with a threshold near and below 1μA.

Single mode photonic quantum ring laser fabricated in hyperboloid drum shape

From three dimensional whispering gallery cavities of GaAs photonic quantum ring fabricated in hyperboloid drum shape by chemically assisted ion beam etching with the central active region diameter of 0.9μm, we have observed single mode lasing near 838nm with a record low injection threshold of 300nA (Jth=47.1A∕cm2) in continuous wave operation at room temperature. This indicates that the quantum ring lasing phenomena associated with the three dimensional whispering gallery modes continue to persist, even at the submicron range overcoming the conventional two dimensional whispering gallery mode limit.

LaGuerre–Gaussian Emission Properties of Photonic Quantum Ring Hole-Type Lasers

We report on the observation of LaGuerre-Gaussian (LG) beam profiles of photonic quantum ring (PQR) hole-type lasers. Naturally formed LG beams are highly valuable for optical tweezering applications, like transporting or manipulating DNA molecules. Various devices with different injection currents and hole diameters have been analyzed.

Polarization characteristics of photonic quantum ring laser with three-dimensional whispering gallery resonances

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.

Resonance spectrum of a three-dimensional photonic quantum ring laser with an equilateral triangle microcavity

We have fabricated three-dimensional (3D) photonic quantum ring lasers with an equilateral triangle microcavity. Their spectra were well explained by combining the off-normal resonance and hexagonally bounced in-plane whispering-gallery-mode condition. The angular distribution of the emission modes and their discrete wavelengths were shown to be in excellent agreement with a 3D Rayleigh Fabry-Perot model. We confirmed that the allowed modes in the equilateral triangle microcavity decrease by decreasing the length of equilateral triangle side, L, and the spectral mode spacing linearly increases with the mode index m and is inversely proportional to L2.

Optical encoder based on rectangular photonic quantum ring laser's orthogonal polarisation states

A new type of optical encoder based on linearly polarised light from a photonic quantum ring (PQR) laser is reported. An encoded track of alternating p1- and p2-orthogonally polarised emission states embedded in a zigzag-shaped PQR laser train is read with a polarised photodetector in order to realise a polarisation-resolved positional detection scheme.

Hole emitter of photonic quantum ring

We report on the observation of “hole” whispering gallery lasers from semiconductor microcavities with three dimensional optical confinement, with thresholds potentially reducible to micro- to nanoampere regimes according to a quadratic size-dependent reduction, consistent with a photonic quantum corral effect of naturally formed recombinant quantum rings. If the device size grows over a critical diameter, the quantum ring whispering gallery then begins to disappear. However, cooperative small hole laser arrays, exhibiting photonic crystal structure properties, avoid the criticality and open a possibility of constructing practical high-density electropumped emitter arrays.

Spectral analysis of a three-dimensional photonic quantum ring laser with a square microcavity

Three-dimensional photonic quantum ring lasers with a square microcavity were fabricated and their spectra were explained by combining two conditions: the off-normal Fabry-Pérot resonance and quadruple-bounced whispering-gallery mode. The angular distribution of the emission modes and their discrete wavelengths were in excellent agreement with a three-dimensional Rayleigh-Fabry-Pérot model. The three-dimensional model also showed that the slope of the spectral mode spacing and the value of the angular mode spacing as a function of the length of a square side L are inversely proportional to L2 and L, respectively.

Photonic quantum corral, carrier ordering, and photonic quantum dot/ring device

This study aims at firstly introducing a theoretical background of photonic quantum ring naturally formed by photonic quantum corral effect in the 3D Rayleigh–Fabry–Perot micro-cavity. This unique phenomenon is visualized as polar angle-dependent multi-chromatic emission spectra corresponding to an each lightwave with different optical paths. Also, we fabricated an H-D structure for a single PQR, i.e. single mode within a luminescent wavelength region and ultra-low threshold 16-K PQR laser array for such as free space optical interconnections.

Wet etching fabrication of photonic quantum ring laser

We present a wet etching process to fabricate good vertical mesa structures that result in high quality (Q) factors up to 2×104, important for smooth sidewall cavities such as the photonic quantum ring (PQR) laser. Q factor analyses also indicate that it can be improved much more once the internal scattering from the wafer materials is minimized. We use an etching solution of H3PO4:CH3OH:H2O2 with a volume ratio of 3:1:1, and a single-layer photoresist etch mask for etching GaAs∕AlGaAs structures of the PQR laser several micrometer deep. As the etching temperature is varied from 20to40°C, the etched surface roughness decreases from 4.690to0.703nm according to scanning electron microscope and atomic force microscopy studies. From the activation energy analysis for the above etching process and the temperature dependence, the etching process is shown to be reaction limited. The PQR lasers with an active diameter of 10μm, fabricated by the wet etching process, show the spectral linewidth of 0.04nm. Three-dimensional Rayleigh-Fabry-Perot mode spectra for the PQR laser are also reported for the angle-resolved emission modes.

A One-Kilobit PQR-CMOS Smart Pixel Array

The photonic quantum ring (PQR) laser is a three dimensional whispering gallery (WG) mode laser and has anomalous quantum wire properties, such as microampere to nanoampere range threshold currents and √T-dependent thermal red shifts. We observed uniform bottom emissions from a 1-kb smart pixel chip of a 32×32 InGaAs PQR laser array flip-chip bonded to a 0.35 µm CMOS-based PQR laser driver. The PQR-CMOS smart pixel array, now operating at 30 MHz, will be improved to the GHz frequency range through device and circuit optimization.

Extremely uniform angular distributions of the three-dimensional emission spectra of photonic quantum ring lasers.

We have observed the emission spectra of three-dimensional Rayleigh-Fabry-Perot cavity whispering-gallery modes from photonic quantum ring lasers that give rise to uniform angular mode spacing in space. The observed angular distribution (0 degrees approximately 30 degrees) of the emission modes is linear with respect to the mode number. For example, the average angular mode spacing is 0.95 degrees with a standard deviation of 0.098 degrees for a 20-microm-diameter laser, whose potential angle-resolving power is promising for angle-sensing applications in the future.

Optical sensing by using photonic quantum ring lasers and resonance-enhanced photodetectors

We describe an optical sensor using photonic quantum ring lasers and resonance-enhanced photodetectors for the purpose of counting object discrimination. Due to the angle-dependent peak wave- length shift characteristics of the photonic quantum ring laser, an emis- sion at an angle of 0;30 deg from a perpendicular direction was re- flected and absorbed in the resonance-enhanced photodetector, with a peak responsivity of 0.107 A/W at 757 nm. The use of the photonic quantum ring laser at an optimized angle in this monolithically integrated system, based on a distributed Bragg partial reflector structure, can lead to a compact, low cost, dust-free optical sensor and counter. © 2002