We have demonstrated an optical scanner based on beam switching method fabricated on silicon photonics integrated circuit. Scanner is based on beam switching method. Scanner is composed of ring resonator multiplexer and grating array. Multiplexer determines the optical path and one of grating is selected for emitter. The scanning angle was 6 degree. Solid state scanner is suitable for Laser intensity direction and ranging (LIDAR) because of reliability and small factor. We fabricated and demonstrated an optical scanner based on beam switching method fabricated on silicon photonics integrated circuit. Scanner is all solid state and movement-free. Scanner is composed of ring resonator multiplexer and grating array. Multiplexer determines the optical path and one of grating is selected for emitter. LIDAR is promising sensor for automated cruising for automotive application and this report is considered to be a remarkable technology.
Photopolymer based three-dimensional (3D) waveguide devices are very attractive in low-cost optical system
integration. Especially, Light-Induced Self-Written (LISW) technology is suitable for this application, and the
technology enables low-loss 3D optical circuitry formation from an optical fiber tip which soaked in photopolymer
solution by employing its photo-polymerization due to own irradiation from the fiber tip. This technology is expected
drastic mounting cost reduction in fields of micro-optic and hybrid integration devices assembly. The principle of the
LISW optical waveguides is self-trapping effect of the irradiation flux into the self-organized waveguide, where, used
wavelength can be chosen to fit photopolymer's reactivity from visible to infrared. Furthermore, this effect also makes
possible grating formation and "optical solder" interconnection. Actually fabricated self-written grating shows well
defined deep periodic index contrast and excellent optical property for the wavelength selectivity. And the "optical
solder" interconnection realizes a passive optical interconnection between two faceted fibers or devices by the LISW
waveguide even if there is a certain amount of gap and a small degree of misalignment exist. The LISW waveguides
grow towards each other from both sides to a central point where the opposing beams overlap and are then combined into
one waveguide. This distinctive effect is confirmed in all kind optical fibers, such as from a singlemode to 1-mm-corediameter
multimode optical fiber. For example of complicated WDM optical transceiver module, mounted a branchedwaveguide
and filter elements, effectiveness of LISW technology is outstanding. In assembling and packaging process,
neither dicing nor polishing is needed. In this paper, we introduce LISW technology principles and potential application
to integrated WDM optical transceiver devices for both of singlemode and multimode system developed in our research
group.
The spectroscopic properties of Tb3+-doped borosilicate glasses are investigated to assess their potential as gain media in
the 0.54 μm band. Analysis of the concentration and temperature dependences of the optical transitions from the 5D4
level of Tb3+ is carried out. The emission lifetime of the 5D4 level at 300 K is found to be 2.61 ± 0.03 ms, and almost
invariant for Tb3+ concentrations less than 15 wt% (1.68×1021 ions/cm3). Judd-Ofelt analysis is used to calculate the
emission transition probabilities from the 5D4 level and the emission cross section at 300 K for the 5D4 →
7F5 transition
was 8.1 × 10-22 cm2 at 541 nm. Temperature dependent non-radiative relaxation of the 5D4 level is observed in samples
with 5 and 20 wt% Tb3+. The quenching process of the 5D4 level in the temperature range of 50 ~ 373 K is thought to be
caused by a two-photon one-site resonant process, whereas it is dominated by a two-site non-resonant process at
temperatures below 40 K. Our results indicate that Tb3+-doped borosilicate glass is a promising candidate for optical gain
media in the green (0.54 μm) band
We demonstrate a 22 dB all-fiber amplifier at 546 nm using Er3+-doped fluoride fiber by forward upconversion pumping
of a 974 nm laser diode. The gain saturation effects and the power conversion efficiency of this amplifier are investigated
in detail based on gain characteristics and numerical simulations.
Visible lasers and amplifiers have potential applications in the fields of optical data storage, spectroscopy, biomedical and
optical local area networks. In this study, Tb3+-Yb3+ co-doped fluorophosphate glasses were synthesized and properties
of the visible emission at 0.54 µm were investigated. A upconversion excitation efficiency from Yb3+ to Tb3+ was studied
by evaluations of a cooperative energy transfer efficiency from Yb3+ to Tb3+ (ηCET) and a back-transfer efficiency from
Tb3+ to Yb3+ (ηBT ) which give positive and negative contribution to upconversion excitation, respectively. The ηCET was
as high as 25 %, and the ηBT was less than 1 % in the fluorophosphate glass. This indicates that Tb3+-Yb3+ co-doped
fluorophosphate glass is promising as new laser and gain media in the 0.54 μm band.
KEYWORDS: Terbium, Ytterbium, Energy transfer, Ions, Glasses, Upconversion, Absorption, Energy efficiency, Acquisition tracking and pointing, Temperature metrology
Spectroscopic analyses have been performed on Tb3+ and Yb3+ co-doped in borosilicate glass, to assess their potential as green laser and amplifier gain media. The energy transfer efficiencies between Tb3+ and Yb3+ are clarified based on experimental observations and numerical analyses on the emission decay dynamics.
Plastic optical fibers (POFs) are beginning to replace electrical wiring in many automotive and home applications. In view of this, we have reported the inexpensive wavelength-division-multiplexing (WDM) device for POF system using the LISW waveguide. The LISW waveguides are an attractive and a low-cost process for realizing self alignment between a POF and a waveguide. In this study, we have investigated about the method for precisely aligned LISW polymeric optical waveguides by using an "optical solder" effect. The "optical solder" effect makes it possible to realize a waveguide connection between two faced optical fibers by radiating from both sides even if a significant gap and a small degree of misalignment exist. When we utilize POFs with core diameters of 700μm, waveguides are combinable on the condition that an offset is 700μm or less and a gap is from 6mm to 13mm. By applying this effect, we fabricated precisely positioned LISW waveguides for optical devices. The fiber ends were set at certain mounting positions with respect to the LEDs and PDs. And we evaluated the positioning accuracy. The resulting positional accuracy at the extremities of the optical waveguides is less than one-tenth of the optical fiber core diameter. This value is sufficiently accurate to realize passive alignment. And this result creates new possibilities for boosting the yield of optical modules in mass-production.
Visible fiber lasers and amplifiers have potential applications in the fields of optical data storage, spectroscopy, biomedical, and optical local area networks. A spectroscopic analysis has been performed on a borosilicate glass, codoped with Tb3+ and Yb3+, to assess this material as a green laser and amplifier medium. The rare-earth ion concentration effect on thermal, absorption, and emission properties of the glasses were investigated using differential scanning calorimetry, UV/VIS/NIR absorption, and luminescence measurements, respectively. These materials were found to have good glass-forming ability, and show a high thermal stability, indicating the potential to facilitate low-loss fiber fabrication. Judd-Oflet analysis was performed for Tb3+ doped in the borosilicate glasses. The radiative lifetime of the 5D4 level was found to be 2.6 ms, and was almost constant in 0.5-15 wt.% concentration range. The peak cross section for stimulated emission by the 5D4->7F5 transition was found to be 0.8×10-21 cm2 at λ = 542 nm. In the Tb3+-Yb3+-codoped glasses, the green emission resulting from the cooperative energy transfer between doped ions was observed under infrared excitation (λex = 0.98 μm). This upconversion emission increased with doping ion concentration. These results suggested that the Tb3+-Yb3+-codoped borosilicate glass is a promising candidate for an all-solid-state upconversion green laser and amplifier.
A new fabrication technique is proposed for the fabrication of optical waveguides for use in optical communication modules with large-core optical fibers. The proposed technique employs a mixed photopolymerizable resin containing two kinds of photopolymerizable monomers that are different in terms of both refractive index and spectral sensitivity. Visible light is irradiated into the resin through an optical fiber in order by take advantage of the self-trapping effect to form the core portion. Only the lowest refractive index monomer is polymerized, with the reaction proceeding from the end of the fiber tip. After the irradiation is over, a concentration gradient is induced in the low refractive index monomer due to the selective area polymerization, which brings about a counter-diffusion phenomenon of the monomeric materials. Diffusion of the low refractive index monomer causes the high refractive index monomer to move out into the region surrounding the core portion. All of the residual monomers are subsequently cured by exposure to UV light. The region with decreased concentration of high refractive index monomer forms a cladding layer. The resultant refractive index profiles of the waveguides were experimentally observed to be "W-shaped". The measured propagation loss of a 700-μm-diameter waveguide was 1.7dB/cm at 0.68-μm wavelength. We are convinced that this technology could serve to automate optical fiber connection and packaging processes in the assembly of optical waveguide modules. This technology is especially useful in short-haul optical communication systems requiring a large-core optical fiber.
We developed the bidirectional optical transceiver module that combined the two LED light sources of different wavelength and three-dimensional (3-D) optical waveguides. By using a light-induced self-written (LISW) technique, we fabricated and tested 3-D optical waveguide circuits for a plastic optical fiber (POF) WDM full-duplex communication module. Because of the large diameter of the POF, an optical waveguide has the advantages, as compared to conventional lens based modules, of a small size and optical low-loss features. The LISW waveguide enables optical components to connect automatically even if the circuit in the module is complex. In this paper, we demonstrate newly developed bidirectional WDM optical module containing 3-D optical circuits, i.e. a branching waveguide and a reflection waveguide, and their optical properties. The module using commercially available green and red LED was constructed and the two-way communication on IEEE1394-S100 (125Mbps) protocol was verified through 10m-length of POF.
In order to simultaneously realize high-speed data transmission, low-cost and lightweight network in automotive applications, a 3(lambda) WDM has been considered to be a suitable solution. We have developed two types of low-cost WDM modules using a polymer optical circuit. As the first method, we developed a planar optical circuit for interconnection between an optical fiber and an LD/PD chip using a PMMA waveguide having out-of-plane branching mirrors, fabricated simultaneously with a waveguide from a polymer film, using a newly-developed temperature-controlled RIE (Reactive Ion Etching) technique. The waveguide has a large diameter (100 x 100micrometers ) and a high-(Delta) (NA=0.5) structure. Transmission losses were 0.1 dB/cm (660nm), and 0.3 dB/cm (1320nm). As the second method, we employed a light-induced waveguide technology for the WDM module fabrication. When a GI optical fiber is soaked in two kinds of light-hardening resin blends in which the hardening wavelength differs ((lambda) 1>(lambda) 2) , the resin is irradiated with (lambda) 1 light through the fiber, a hardened polymer waveguide having uniform diameter geometry would grow from the fiber tip. This method does not need any fiber alignment and packaging process; therefore, cost-effective module fabrication can be expected. This technique utilizes the self-focusing phenomenon of the optical fiber's outgoing beam by a refractive index increase in the material hardening process. We could also confirm two key component formations necessary for the WDM module: regrowth of the waveguide form the backside of a WDM filter after passing through it, and a 90 degree(s) reflected waveguide using a 45 degree(s) mirror.
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