RESUMEN
We demonstrate high-output-power and high-efficiency operation of 1.3-µm-wavelength InP-based photonic-crystal surface-emitting lasers (PCSELs). By introducing a metal reflector and adjusting the phase of the reflected light via optimization of the thickness of the p-InP cladding layer, we successfully achieve an output power of approximately 400â mW with the slope efficiency of 0.4 W/A and the wall-plug efficiency of 20% under CW conditions. In addition, this PCSEL exhibits a narrow circular beam with a divergence angle below 1.6° even at high output powers under CW conditions at temperatures from 15°C to 50°C. We have also demonstrated an output power of over 12 W under pulsed conditions at room temperature.
RESUMEN
Short-pulse high-peak-power lasers are crucial laser sources for various applications such as non-thermal ultrafine material processing and eye-safe high-resolution remote sensing. Realizing such operation in a single semiconductor laser chip without amplifiers or external resonators is expected to contribute to the development of compact, affordable laser sources for such applications. In this paper, we demonstrate short-pulse high-peak-power photonic-crystal surface-emitting lasers based on simultaneous absorptive and radiative Q-switching. The proposed device induces an instantaneous and simultaneous decrease in both absorptive and out-of-plane radiation losses due to saturable absorption and self-evolution of the photonic band, respectively, which results in drastic Q-switching operation of the device. Based on this concept, we experimentally demonstrate short-pulse generation with 200-W-class peak power and a pulse width of < 30 ps. In addition, via pulse compression with dispersion compensation, we achieve an even higher peak power of â¼300 W with a shorter pulse width of â¼10 ps.
RESUMEN
Flash light sources with a wide field of view (FOV) are indispensable in various fields such as light detection and ranging (LiDAR), optical wireless communication, and adaptive lighting. However, conventional flash light sources, which combine lasers with external optical elements, tend to suffer from high complexity, large size, and high cost. In this study, we investigate a new wide-FOV flash light source which does not require external optical elements, based on a dually modulated photonic crystal surface-emitting laser (PCSEL). First, we propose and design the concept of a photonic crystal into which information of gradually varying diffraction vectors is introduced in order to artificially broaden the divergence angle. We then experimentally demonstrate photonic crystals based on this concept. Finally, by arraying 100 such lasers with mutually different central emission angles and driving all of these lasers simultaneously, we successfully achieve optics-free, 4-W flash illumination over a FOV of 30° × 30° at a wavelength of 940â nm.
RESUMEN
We demonstrate high-power continuous-wave (CW) lasing oscillation of 1.3-µm wavelength InP-based photonic-crystal surface-emitting lasers (PCSELs). Single-mode operation with an output power of over 100â mW, a side-mode suppression ratio (SMSR) of over 50â dB, and a narrow single-lobe beam with a divergence angle of below 1.2° are successfully achieved by using a double-lattice photonic crystal structure consisting of high-aspect-ratio deep air holes. The double lattice is designed to enhance both the in-plane optical feedback and the surface radiation effects in the photonic crystal. The coupling coefficients for 180 ∘, +90 ∘, and -90 ∘ diffractions are estimated from the measurements of the photonic band structure as κ1D = 417 cm-1, κ2D+ = 135 cm-1, and κ2D- = 65 cm-1, respectively. The stable single-mode, high-beam-quality operation is attributed to these large coupling coefficients introduced by the asymmetric double-lattice structure.
RESUMEN
We develop a self-consistent theoretical model for simulating the lasing characteristics of photonic-crystal surface-emitting lasers (PCSELs) under continuous-wave (CW) operation that takes into account thermal effects caused by current injection. Our model enables us to analyze the lasing characteristics of PCSELs under CW operation by solving self-consistently the changes in the in-plane optical gain and refractive index distribution, which is associated with heat generation and temperature rise, and the change in the oscillation modes. We reveal that the lasing band-edge selectivity and beam quality of the PCSELs are affected by the spatial distribution of the band-edge frequency of the photonic crystal formed by the refractive index distribution, which depends on the temperature distribution in the resonator. Furthermore, we show that single-mode lasing with narrow beam divergence can be realized even at high current injection under CW operation by introducing a photonic-crystal structure with an artificially formed lattice constant distribution, which compensates such band-edge frequency distribution.
RESUMEN
We report on electrically driven InP-based photonic-crystal surface-emitting lasers (PCSELs), which possess a deep-air-hole photonic crystal (PC) structure underneath an active region formed by metal-organic vapor-phase-epitaxial (MOVPE) regrowth. Single-mode continuous-wave (CW) lasing operation in 1.3-µm wavelength is successfully achieved at a temperature of 15°C. It is shown that the enhancement of lateral growth during the MOVPE regrowth process of air holes enables the formation of deep air holes with an atomically flat and thin overlayer, whose thickness is less than 100â nm. A threshold current of 120â mA (threshold current density = 0.68â kA/cm2) is obtained in a device with a diameter of 150â µm. A doughnut-like far-field pattern with the narrow beam divergence of less than 1° is observed. Strong optical confinement in the PC structure is revealed from measurements of the photonic band structure, and this strong optical confinement leads to the single-mode CW lasing operation with a low threshold current density.
