We present evaluation results of the 940nm 400mW transverse single-mode laser diodes (LDs) with real reflective index self-aligned (RISA) structure based on graded index separate confinement hetero structures (GRIN-SCH) for a three-dimensional (3D) depth sensor. The AlGaAs/InGaAs laser diodes that are adopted with RISA structure have many advantages over conventional complex refractive index guided lasers, what include low operating current, high temperature operation and stable fundamental transverse-mode operation up to high power levels.
Simultaneously, the RISA process is easy to control the waveguide channel width and does not require stable oxide mask for the regrowth of aluminum alloys, so it is possible to manufacture high output power and high reliability laser diodes.
At the optical power 400mW under the continuous-wave (CW) operation, Gaussian narrow far-field patterns (FFP) are measured with the full-width at half-maximum vertical divergence angle of 23°. A threshold current (Ith) of 33mA, slope efficiency (SE) of 0.81mW/mA and operating current (Iop) of 503mA are obtained at room temperature. Also, we could achieve catastrophic optical damage (COD) of 657mW and long-term reliability of 60°C with TO-56 package.
975-nm laser diodes (LDs) are of great demand as pumping sources for Yb-doped fiber lasers. They should provide high output power with high efficiency and good beam quality. In order to satisfy these requirements, the LD structure should be carefully designed. In this paper, we report the results of our investigation in which the influence of the LD emitter width on the maximum output power, power-conversion efficiency (PCE) and beam parameter product (BPP) are analyzed with self-consistent electro-thermal-optical simulation of LDs. In order to establish the accuracy of our simulation, we carefully determine the numerical values of key LD parameters by fitting the simulation results to the measured results for a fabricated 975-nm LD. The device has 15-nm-thick tensile-strained InGaAsP single quantum well with asymmetric AlGaAs separate confinement heterostructure layers, 90-μm wide ridge, and 4-mm long cavity. With the parameter values obtained, LDs having various emitter widths are simulated and their maximum output powers, PCEs, and BPPs are determined as well as the temperature profiles inside the device. The results show that the device with the smaller emitter width has both of thermal roll-over, thermal blooming at the lower output power, mostly due to higher series resistance. However, it provides better BPP. These results are useful for optimizing LD array structures so that the optimal structure for each array element can be determined that can provide the highest possible output power with the best BPP.
In this paper, we report the results of our investigation about 940nm AlGaAs/InGaAs single mode laser diodes adopting graded index separate confinement hetero structures (GRIN-SCH) and p, n-clad asymmetric structures with improved temperature and small divergence beams characteristics under the high output power operation for a 3D motion recognition sensors. The GRIN-SCH design provides good carrier confinement and prevents current leakage by adding a grading layer between clad and waveguide layers. In addition, the dopant concentration of the cladding layer is optimized to reduce resistance and internal loss. At the optical power 300mW, measured average values of threshold current (Ith), operating current (Iop), slop efficiency (SE), operating voltage (Vop), peak wavelength (λ) are 80mA, 352mA, 1.12mW/mA, 1.87V, 940nm respectively. Also, we could obtain catastrophic optical damage (COD) of 750mW and excellent long-term reliability characteristic 60°C with TO-56 package. From the experimental measurement results, the developed 940nm high power laser diode is suitable optical source for the sensor applications including 3D motion recognition sensors.
We investigated a novel design concept of index-guided tapered LDs with linearly effective-refractive-index variation to make a quality beam in 808 nm for intermediate power LDs between a few decades of mW to ~ W. In this concept, the tapered width at each position in the propagation direction varies linearly depending on change in effective-refractive-index not geometry. We use GaAsP/InGaP/InGaAlP quantum well LD structure of 808 nm and standard LD fabrication processes to test. To design a detail structure, we use the effective-refractive-index method and transfer matrix method. The tapered ridge LD with linear effective-refractive-index variation shows more stable in beam quality but needs more study to optimize the structure.
In this paper, next generation 780nm monolithic individually addressable 8 beam diode laser with 10mW optical
power for laser scanning unit were developed. Beam to beam spacing is 30μm and air bridge interconnection process
was developed for individual operations. Measured average values of threshold current(Ith), operating current(Iop),
operating voltage(Vop), slope efficiency(SE), horizontal beam divergence(FFH), vertical beam divergence(FFV), and
peak wavelength(λ) from 5 specimens are 14.91mA, 28.79mA, 1.91V, 0.72mW/mA, 8.28°, 31.89°, and 785.67nm
respectively. Major electro-optic parameters from 8 emitters are within 3% variation for each device. Also we measured
power droop that had a strong influence on printing image at 600Hz with duty 10% and 90% and we can obtained droop
rate within 2% in each channel at room temperature and 10mW power. From 500Hr reliability life test result at 70°C,
we obtained Iop variation within 1% in each channel with 10mw power.
From the experimental measurement results, we can assure that the developed 8 beam diode laser is suitable optical
source for high speed laser scanning unit in multi-function printing system and laser beam printers.