New Scheme of MEMS-Based LiDAR by Synchronized Dual-Laser Beams for Detection Range Enhancement.

A new scheme presents MEMS-based LiDAR with synchronized dual-laser beams for detection range enhancement and precise point-cloud data without using higher laser power. The novel MEMS-based LiDAR module uses the principal laser light to build point-cloud data. In addition, an auxiliary laser light amplifies the single-noise ratio to enhance the detection range.

Microlens array device for laser light shaping in laser scanning smart headlights.

We present, what we believe to be, a novel microlens array (MLA) scheme for laser light shaping in laser scanning smart headlight. The laser spot has a Gaussian distribution that may reach a high peak power density in the central part, which is called hot spot. When the laser beam is applied to a phosphor plate for luminous conversion, the hot spot of Gaussian beam causes thermal quench and decreases luminous efficacy.

High color rendering index of 94 in white LEDs employing novel CaAlSiN: Eu and LuAlO: Ce co-doped phosphor-in-glass.

High color rendering index (CRI) and wide correlated color temperatures (CCTs) white LEDs (WLEDs) employing CaAlSiN: Eu and LuAlO: Ce co-doped phosphor-in-glass (PiG) are demonstrated. Through fabrication using a low sintering temperature of 620°C to minimize inter-diffusion between the red phosphor and glass, and adjusting thickness of 0.5-0.

New scheme of LiDAR-embedded smart laser headlight for autonomous vehicles.

A new scheme of LiDAR-embedded smart laser headlight module (LHM) for autonomous vehicles is proposed and demonstrated. The LiDAR sensor was fabricated by LeddarTech with the wavelength of 905-nm, whereas the LHM was fabricated by a highly reliable glass phosphor material that exhibited excellent thermal stability. The LHM consisted of two blue laser diodes, two blue LEDs, a yellow glass phosphor-converter layer with a copper thermal dissipation substrate, and a parabolic reflector to reflect the blue light and the yellow phosphor light combined into white light.

An advanced laser headlight module employing highly reliable glass phosphor.

An advanced laser headlight module (LHM) employing highly reliable glass phosphor is demonstrated. The novel glass-based YAG phosphor-converter layers fabricated by low-temperature of 750°C exhibited better thermal stability. The LHM consisted of a 5 × 1 blue laser diode array, an aspherical lens, a glass phosphor-converter layer with an aluminum thermal dissipation substrate, and a dichroic filter to allow pass blue light and reflect yellow phosphor light.

Micro-hyperboloid lensed fibers for efficient coupling from laser chips.

A novel technique is presented for producing micro-hyperboloid lensed fibers for efficient coupling to semiconductor laser chips. A three-step process including a precision mechanical grinding, a spin-on-glass (SOG) coating and an electrostatic pulling process is used to form the hyperboloid lens structure on a flat-end single mold fiber (SMF) with the core diameter of 6.6 μm.

Comparison of single-/few-/multi-mode 850 nm VCSELs for optical OFDM transmission.

For high-speed optical OFDM transmission applications, a comprehensive comparison of the homemade multi-/few-/single-transverse mode (MM/FM/SM) vertical cavity surface emitting laser (VCSEL) chips is performed. With microwave probe, the direct encoding of pre-leveled 16-QAM OFDM data and transmission over 100-m-long OM4 multi-mode-fiber (MMF) are demonstrated for intra-datacenter applications. The MM VCSEL chip with the largest emission aperture of 11 μm reveals the highest differential quantum efficiency which provides the highest optical power of 8.

Efficient Heat Dissipation of Uncooled 400-Gbps (16×25-Gbps) Optical Transceiver Employing Multimode VCSEL and PD Arrays.

An effective heat dissipation of uncooled 400-Gbps (16×25-Gbps) form-factor pluggable (CDFP) optical transceiver module employing chip-on-board multimode 25-Gbps vertical-surface-emitting-laser (VCSEL) and 25-Gbps photodiode (PD) arrays mounted on a brass metal core embedded within a printed circuit board (PCB) is proposed and demonstrated. This new scheme of the hollow PCB filling with thermally-dissipated brass metal core was simulated and used for high temperature and long term stability operation of the proposed 400-Gbps CDFP transceiver. During one-hour testing, a red-shift of central wavelength by 0.

Broadband Ce/Cr-doped crystal fibers for high axial resolution OCT light source.

The fabrication and characteristics of Ce/Cr-doped crystal fibers employing drawing tower technique are reported. The fluorescence spectrum of the Ce/Cr fibers at the core diameter ranging from 10 to 21 µm exhibited a 200-nm near-Gaussian broadband emission which enabled to provide an axial resolution of 1.8-μm and a power density of 79.

Chromaticity tailorable glass-based phosphor-converted white light-emitting diodes with high color rendering index.

In this paper, Lu3Al5O12:Ce3+ and CaAlSiN3: Eu2+ co-doped glass are presented as color conversion materials for white light-emitting diodes (WLEDs). Through adjusting the thickness of the glass phosphors, the chromaticity and CCT of the WLEDs follows the Planckian locus well. The WLEDs show CCT ranging from ~4000K to ~7000K with high CRI ranging from 83 to 90 due to the wide emission spectrum from the proposed glass phosphors.

Novel broadband glass phosphors for high CRI WLEDs.

New broadband glass phosphors with excellent thermal stability were proposed and experimentally demonstrated for white light-emitting-diodes (WLEDs). The novel glass phosphors were realized through dispersing multiple phosphors into SiO₂ based glass (SiO₂-Na₂O-Al₂O₃-CaO) at 680°C. Y₃Al₅O₁₂:Ce³⁺ (YAG), Lu₃Al₅O₁₂:Ce³⁺ (LuAG), and CaAlSiN₃: Eu²⁺ (nitride) phosphor crystals were chosen respectively as the yellow, green, and red emitters of the glass phosphors.

Fluorescence enhancement in broadband Cr-doped fibers fabricated by drawing tower.

The fluorescence enhancement in broadband Cr-doped fibers (CDFs) fabricated by a drawing tower with a redrawn powder-in-tube preform is proposed and demonstrated. The CDFs after heat treatment exhibited Cr⁴⁺ emission enhancement with spectral density of 200 pW/nm, verified by the formation of α-Mg₂SiO₄ nanocrystalline structures in the core of CDFs. The high fluorescence achievement in the CDFs is essential to develop a broadband CDF amplifier for next-generation optical communication systems.

Stable mode-locked fiber laser based on CVD fabricated graphene saturable absorber.

A stable mode-locked fiber laser (MLFL) employing multi-layer graphene as saturable absorber (SA) is presented. The multi-layer graphene were grown by chemical vapor deposition (CVD) on Ni close to A-A stacking. Linear absorbance spectrum of multi-layer graphene was observed without absorption peak from 400 to 2000 nm.

Liquid crystal modified photonic crystal fiber (LC-PCF) fabricated with an un-cured SU-8 photoresist sealing technique for electrical flux measurement.

The optical transmission properties of photonic crystal fibers (PCFs) can be manipulated by modifying the pattern arrangement of the air channels within them. This paper presents a novel MEMS-based technique for modifying the optical transmission properties of commercial photonic-crystal fiber (PCF) by selectively filling the voids within the fiber structure with liquid crystals. In the proposed approach, an un-cured SU-8 ring pattern with a thickness of 5 μm is fabricated using a novel stamping method.

Pulse shortening mode-locked fiber laser by thickness and concentration product of carbon nanotube based saturable absorber.

The dependence of thickness and concentration product (TCP) of single-wall carbon nanotubes saturable absorber (SWCNTs SA) on stabilizing and shortening pulsewidth in mode-locked fiber lasers (MLFLs) was investigated. We found that an optimized TCP for pulse energy and nonlinear self-phase modulation (SPM) enabled to determine the shorter pulsewidth and broader 3-dB spectral linewidth of the MLFLs. The shortest MLFL pulsewidth of 418 fs and broad spectral linewidth of 6 nm were obtained as the optimized TCP was 70.

Direct near-field phase measurement of laser diodes employing a single-mode fiber interferometer.

A method of direct measurement of near-field phase and intensity distribution of laser diodes employing a single-mode fiber interferometer is proposed and demonstrated. The phase and intensity of the output beam of the laser in the vicinity of the output facet are measured directly via interferometry. Using a 980 nm laser diode as an example, we obtained a beam width of 0.

Concentration effect of carbon nanotube based saturable absorber on stabilizing and shortening mode-locked pulse.

We comprehensively investigated the concentration effect of dispersed single-walled carbon nanotubes (SWCNTs) in polymer films for being a saturable absorber (SA) to stabilize the mode locking performance of the erbium-doped fiber laser (EDFL) pulse through the diagnosis of its nonlinear properties of SA. The measured modulation depth was from 1 to 4.5% as the thickness increased 18 to 265 microm.

Photo and electrical tunable effects in photonic liquid crystal fiber.

This work demonstrates photo alignment and electrical tuning effects in photonic liquid crystal fiber (PLCF). Applying voltages of 0 approximately 130V and 250 approximately 400V shifts the short and long wavelength edges of the transmission bands by about 45 nm and 74 nm toward longer wavelengths, respectively. An electro-tunable notch filter is formed in the PLCF without the use of gratings.

Fabrication and Performance of MEMS-Based Pressure Sensor Packages Using Patterned Ultra-Thick Photoresists.

A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were investigated by using a finite-element (FE) model and experimental measurements.

Wavefront measurements of diode laser beams with large dynamic ranges.

We propose and demonstrate a method for the measurement of the wavefronts of high-power diode laser beams with large dynamic ranges. Our wavefront sensor consists of a movable pinhole and a wavefront-slope detector. The measurement results show that the wavefront sensor exhibits a large dynamic range of pi/2 to -pi/2 and a high precision on the measured average wavefront slope.

Mode matching and insertion loss in ultrabroadband Cr-doped multimode fibers.

We investigate the fundamental insertion loss due to mode mismatch in an optical link involving a single-mode fiber-optic (SMF) transmission with the insertion of a segment of a multimode Cr(4+)-doped fiber (MMCDF). With an MMCDF core diameter of approximately 15.5 microm that matches the SMF, we obtained coupling efficiencies of 60.

Preform fabrication and fiber drawing of 300 nm broadband Cr-doped fibers.

The fabrication of a Cr-doped fiber using a drawing-tower method with Cr:YAG as the core of the preform is presented. The Cr-doped YAG preform was fabricated by a rod-in-tube method. By employing a negative pressure control in drawing-tower technique on the YAG preform, the Cr-doped fibers with a better core circularity and uniformity, and good interface between core and cladding were fabricated.

Simple parameter determination for twisted nematic liquid-crystal display.

A simple and accurate measurement method for determining the cell parameters of a twisted nematic liquid-crystal display (TN-LCD) is proposed. Based on the measurement of the maximum reflectance and the maximum transmittance of a TN-LCD by rotating the polarizer at a particular angle, between the front director of the liquid crystals and the transmission axis of the polarizer, the cell gap and the twist angle can be determined according to the Jones matrix theory, and the twist sense can also be determined easily by applying an external small voltage to slightly change the effective refractive index of the liquid crystal.

Asymmetric elliptic-cone-shaped microlens for efficient coupling to high-power laser diodes.

A new scheme of asymmetric elliptic-cone-shaped microlens (AECSM) employing a single-step fabrication technique for efficient coupling between the high-power 980-nm laser diodes and the single-mode fibers is proposed. The AECSMs are fabricated by asymmetrically shaping the fiber during the single-step grinding process and elliptically lensing the fiber tip during the fusing process. A maximum coupling efficiency of 85% and a high-average coupling efficiency of 71% have been demonstrated for a 980-nm laser diode with a high aspect ratio of 5.