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In this study, we fabricated a photoelectrochemical circuit using GaInAsP photonic crystal nanolasers as a working electrode. Then, we controlled the emission intensity and lasing wavelength of these nanolasers by applying a bias voltage in an ionic solution. The electrochemical working points for the emission intensity and wavelength were observed for the backward and forward biases, respectively. We confirmed that the emission intensity is primarily changed by the surface recombination, which is enhanced by the Schottky barrier near the solid–liquid interface. The wavelength shift is also assumed to be caused by the Pockels effect in the electric double layer of the solution. This control method can maximize and stabilize the performance of photonic biochemical sensors and also become an option in controlling the laser diode characteristics., This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in (Yoshito Saijo et al 2019 App. Phy. Let. 114 221105) and may be found at http://doi.org/10.1063/1.5098119.

By the two-dimensional triangular holey structure, a high-power stable single-mode operation was demonstrated in oxide confined 850nm vertical-cavity surface-emitting lasers. For two types of hole alignments, the lasing operation was observed with different near field patterns, i.e., a single spot pattern and a floral pattern. The former showed an output power of 2mW with a high side-mode suppression ratio (SMSR) of 45–50dB, which is explained by the selective loss mechanism. The latter showed a high power of 7mW with a SMSR of 40dB. The observed lasing spectrum and far field pattern indicate that it is a deformed fundamental mode whose bright spots extending over the device are in-phase oscillating. This device structure will be effective for the enhancement of single-mode power in devices with any material system.

Previously, we proposed and demonstrated chirped photonic crystal waveguides, in which some structural parameters are gradually changed so that the photonic band characteristic is smoothly shifted. In this letter, we discuss an optical delay line composed of two index-chirped waveguides in a directional coupler structure. A large delay is realized by a low average group velocity of

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. (C) 2004 American Institute of Physics.

We demonstrate a light-emitting diode exhibiting 1.7-2.7-fold enhancement in light extraction efficiency compared with that for a planer device. It has a two-dimensional surface grating photonic crystal, which diffracts internal light with a large solid angle into the escape light cone. Due to its shallow grating separated from the active layer and micron order lattice constant, the fabrication process is simple, applicable to arbitrary semiconductor devices, and free from process-induced nonradiative recombinations. (C) 2004 American Institute of Physics.

We have established a profitable fabrication technique for three-dimensional (3D) photonic crystals for optical wavelengths. In our method, two-dimensional photonic plates, which serve as unit parts for 3D structures, are prepared by the semiconductor nanofabrication technique. Then, these plates are assembled into 3D structures by micromanipulation. Accurate lamination of the plates is assured by linking fiducial holes of neighboring plates with matching microspheres. With this technique, we have succeeded in fabricating 3D photonic crystals with one to four layers of woodpile structures. From scanning electron microscope observation of the crystals, the periodic error was determined to be within 50 nm. The optical properties of the crystals indicate existence of the photonic band gap at the expected wavelength of 3–4 μm.

From lasing wavelengths observed for many samples of microdisk lasers with GaInAsP compressively strained quantum wells (CS-QWs), we estimate the gain peak redshifted by ∼10 meV. We explain this phenomenon as the strain relaxation in the CS-QWs at the disk wing exposed to the air. Band and rate equation analyses show that the built-in potential by strain relaxation accelerates the carrier diffusion toward the disk edge and reduces the threshold to 30%–60% of that without strain relaxation. This result indicates the advantage of CS-QWs not only for the microdisk laser but also for various microlasers with a membrane structure, e.g., photonic crystal slab lasers.

We evaluated the surface recombination velocity vs of 1.55 μm GaInAsP microcolumns through the measurement of carrier lifetime using the phase-resolved spectroscopy. We investigated various surface treatments and confirmed that vs was reduced to nearly half of that for as-etched microcolumns by CH4 electron cyclotron resonance plasma irradiation. This result was ensured by the two- to fivefold increase in photoluminescence intensity. The secondary ion mass spectroscopy analysis suggested that the reduction in vs was attributable to the deposition of a polymer, the hydrogenated hard carbon, etc., and/or a carbon deep level formed near the surface.

Evanescent field profiles of whispering gallery (WG) modes in a 1.6-mu m-GaInAsP microdisk injection laser were investigated by scanning a nanoprobe near the periphery of a lasing microdisk. The increase in threshold current due to the light scattering by the probe and the corresponding decrease in laser light were observed experimentally. Two-dimensional images of the evanescent field, which agreed well with theoretical expectations, were obtained by the use of a Pt-Ir probe. The images indicate that the WG mode is strongly locked by the fourfold symmetry in the microdisk with center post claddings. This characteristic is favorable for the microdisk laser itself to be used as an active near-field probe. A lower contrast image obtained by the use of a tapered silica fiber probe suggests that the microdisk probe can be sensitive to both surface profiles and optical properties of the object. (C) 2000 American Institute of Physics. [S0003-6951(00)01737-X].

Fast and reliable detection of endotoxin (ET) in medical equipment and pharmaceutical products is an essential precursor to clinical treatment. In this study, we demonstrate the use of shifts in wavelength of photonic crystal nanolasers for sensing the Limulus amebocyte lysate reaction, which is a standard method for detecting ET. From working curves of wavelength shift vs ET concentration, whose correlation factors were as high as 98%, we detected a required concentration of 0.001 EU/ml within 33 min and detected a low concentration of 0.0001 EU/ml.

Photonic crystal (PC) nanolasers often consist of air-bridge PC slab, which enhances optical confinement while limiting its size to 30 × 30 μm2 due to the mechanical fragileness. This limit is broken by resin-mediated bonding of the PC slab on a host substrate. In this paper, we demonstrate a GaInAsP PC slab with a size of over 100 × 100 μm2 in which 1089, 2376, and 11 664 nanolasers showing high-yield laser operation are integrated.

We demonstrate two-photon-absorption photodiodes in Si photonic-crystal waveguides, which shows wideband low-dispersion slow light. The device was fabricated on SOI substrate by CMOS-compatible process. The responsivity was improved by higher group indexes of slow light up to 0.052 A/W for pulses at wavelengths around 1550 nm with a 2.7 ps width and sub-watt peak powers. We applied this device to an optical correlator and dispersion detector. In the former, the correlation waveforms of 0.7−10 ps pulses were observed with small errors. In the latter, photocurrents inversely proportional to the pulse width were detected.

We fabricated photonic crystal slow light waveguides integrated with multi-heaters, using CMOS-compatible process. By optimizing heating powers and adjusting the index distribution, a clear delay peak was observed, which suggests that the fabrication errors were compensated for completely. When a linear index chirp was added to this condition, the delay was tuned by 54 ps. When a quadratic chirp was added, arbitrary group delay dispersion was generated at wavelengths around 1550 nm within a 3 nm bandwidth. The continuously tunable range was from −32 to 54 ps/nm/mm. Using this as a dispersion compensator, we compressed pre-chirped pico-second pulses.

Photonic crystal nanolasers have a drawback of weak vertical emission, which degrades the detection efficiency from above. We show that the vertical emission is enhanced greatly by introducing asymmetry to the cavity, so that Fourier components around the Brillouin zone boundary are shifted to the zone center. When the light output is collected from above by an objective lens with a numerical aperture of 0.42, the efficiency for the optimized devices, with and without nanoslot, are calculated to be 26 and 153 times that of the original structure. We confirm the experimental and calculated results to be in good agreement.

We propose and demonstrate photonic crystal nanolaser with a nanoslot. Using high-aspect etching process, we succeed in fabricating a 30-nm-wide nanoslot device and room temperature lasing in both air and liquids. As an index sensor, it exhibits a high sensitivity of 410 nm per refractive index unit, as well as low temperature dependence in water. These behaviors and theoretical analysis suggest that the mode is strongly localized in the nanoslot. This device will be effective for enhancing light-matter interaction in cavity quantum electro dynamics, nonlinear optics, and biosensing.

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 mu m(3)similar to 2.1(lambda/2n)(3), which is the smallest in any kind of laser. Such an ultrasmall modal volume will ensure efficient electron-photon coupling. (c) 2006 American Institute of Physics.

We investigated propagating modes in a two-dimensional photonic crystal slab waveguide with a line defect narrower than a single line missing hole structure from the low group velocity point of view. These modes showed low group velocities not due to the conventional distributed feedback (DFB) between a forward and a backward mode with the same lateral field distribution, but due to a DFB between modes with different lateral field distribution or property of a start point of a photonic-band-gap-guided mode. These low group velocities of over 40 were demonstrated as a Fabry-Perot lasing oscillation due to gain enhancement.

We fabricated a photonic molecule consisting of GaInAsP microdisks, and obtained the lasing operation by photopumping. We also observed mode splits arising from the optical coupling, which was confirmed by an anticrossing characteristic against the disk diameter detuning and a miniband being dependent on the number of disks, their arrangement and coupling strength. The coupling characteristics were explained by considering bonding and antibonding states of modes, and by finite-difference time-domain calculation. Such a laser is expected to be some functional devices, and the concept of the photonic molecule will be helpful for the understanding of complex coupled modes.