Total Reflection Mirrors Research Articles

Generation of an X-ray microbeam for spectromicroscopy at SPring-8 BL39XU.

A pair of elliptical mirrors (KB mirror) was designed and fabricated to realize an energy tunable x-ray microbeam for spectromicroscopy at SPring-8 BL39XU. As is commonly recognized, the obtainable beam size with the aspherical total reflection mirrors is strongly affected with the slope error of the mirror. Considering that the extremely high brilliance of the undulator radiation from the SPring-8, the small mirror size and the small mirror-to-focus distance were employed to minimize effects of the slope error. Preliminary evaluation of the KB mirror was carried out using 10 keV monochromatized undulator radiation. Alignment of the mirror was assisted by the beam monitor system composed of a scintillator and a CCD, and the beam size less than 5 microm can be easily achieved even when the source was fully used. The beam size obtained with this experiment was 2 x 4 microm2 with the photon flux of 1 x 10(10) photons/s. Smaller beam size may be expected with the use of intermediate slits. Characterization of trace elements with the spatial resolution will be carried out by using x-ray fluorescence (XRF) analysis and x-ray absorption fine structure (XAFS) measurements with XRF yield method.

Fully embedded board-level guided-wave optoelectronic interconnects

A fully embedded board-level guided-wave optical interconnection is presented to solve the packaging compatibility problem. All elements involved in providing high-speed optical communications within one board are demonstrated. Experimental results on a 12-channel linear array of thin-film polyimide waveguides, vertical-cavity surface-emitting lasers (VCSELs) (42 /spl mu/m), and silicon MSM photodetectors (10 /spl mu/m) suitable for a fully embedded implementation are provided. Two types of waveguide couplers, titled gratings and 45/spl deg/ total internal reflection mirrors, are fabricated within the polyimide waveguides. Thirty-five to near 100% coupling efficiencies are experimentally confirmed. By doing so, all the real estate of the PC board surface are occupied by electronics, and therefore one only observes the performance enhancement due to the employment of optical interconnection but does not worry about the interface problem between electronic and optoelectronic components unlike conventional approaches. A high speed 1-48 optical clock signal distribution network for Cray T-90 super computer is demonstrated. A waveguide propagation loss of 0.21 dB/cm at 850 nm was experimentally confirmed for the 1-48 clock signal distribution and for point-to-point interconnects. The feasibility of using polyimide as the interlayer dielectric material to form hybrid three-dimensional interconnects is also demonstrated. Finally, a waveguide bus architecture is presented, which provides a realistic bidirectional broadcasting transmission of optical signals. Such a structure is equivalent to such IEEE standard bus protocols as VME bus and FutureBus.

High-efficiency unitraveling-carrier photodiode with an integrated total-reflection mirror

A novel photodiode (PD) structure with an integrated total-reflection mirror which can enhance the quantum efficiency in back-illuminated geometry is proposed. Due to the diagonal propagation of the reflected light at the total-reflection mirror through the absorption layer, the efficiency is improved by about 50% from that of the normally irradiated case. By employing a unitraveling-carrier structure together with a thick absorption layer of 4700 A, the fabricated PD exhibits a high responsivity of 0.65 A/W, a high 3-dB bandwidth of 50 GHz, and a high-output voltage of 5 V, simultaneously.

Silicon Micromachined Fiber-Optic Accelerometer for Downhole Seismic Measurement

The fabrication and characterization of a fiber-optic micro accelerometer for downhole seismic measurement is described. This sensor consists of a Fabry-Perot interferometer using a half-mirror at the end of an optical fiber and a total reflection mirror on a silicon mass suspended with thin beams. When acceleration is applied to the sensor, the intensity of the reflected light is modulated interferometrically according to the displacement of the silicon mass.The sensor is fabricated by using silicon micromachining and hence is small sized (6.6mm in diameter and 11mm in height) and cost effective. By reason of the small size and the low cost, it is possible to install many sensors in a micro borehole. Since the sensor has not active devices like transistors, it can stand in harsh environment i.e. high temperature. The fabricated sensor has the frequency range from DC to 300Hz, the maximum detectable acceleration of 0.27g and the dynamic range of 36dB.

Monolithic-integrated microlaser encoder

We have developed an extremely small integrated microencoder whose sides are less than 1 mm long. It is 1/100 the size of conventional encoders. This microencoder consists of a laser diode, monolithic photodiodes, and fluorinated polyimide waveguides with total internal reflection mirrors. The instrument can measure the relative displacement between a grating scale and the encoder with a resolution of the order of 0.01 microm; it can also determine the direction in which the scale is moving. By using the two beams that were emitted from the two etched mirrors of the laser diode, by monolithic integration of the waveguide and photodiodes, and by fabrication of a step at the edge of the waveguide, we were able to eliminate conventional bulky optical components such as the beam splitter, the quarter-wavelength plate, bulky mirrors, and bulky photodetectors.

Trace Chemical Characterization of Liquid Drop by Fluorescence Detection of Absorption Edge Shifts using Total Reflection Support

An analytical technique to investigate the chemical state of trace metals in a small amount of sample has been proposed. While the principle for distinguishing the chemical state is based on well known X-ray spectroscopic phenomena, i.e., chemical shifts of the absorption edges, a total reflection mirror has been employed as a support to enhance the signal to background ratio through the reduction of scattering X-ray background. The present paper describes the details of the analytical procedure and shows the successful results of the near edge absorption spectrum of trace iron (∼mM) in a wet liquid drop (∼ μl) measured in 3 ∼ 5 min. The feasibility of the application to biomedical science is also mentioned.

New optical and electrical hybrid packaging techniques using optical waveguides for optoelectronic multichip modules

An optoelectronic multichip module (OE-MCM) using fluorinated polyimide optical waveguides is proposed. This module can be produced with an optoelectrical substrate (OE-substrate), incorporating photodiode-to-waveguide coupling, and fiber-to-waveguide coupling. The OE-substrate is composed of fluorinated polyimide optical waveguides fabricated onto a copper-polyimide multilayer electrical substrate. Propagation loss of the optical waveguide is low at 0.4 dB/cm. There is no change in the optical characteristics of the waveguide after heat-treatment during the solder bonding process. The waveguide-to-photodiode coupling is achieved by deflecting the propagating light with a total internal reflection (TIR) mirror, and self-alignment of the photodiode is achieved using micro-solder bumps. The TIR mirror shows low reflection loss of less than 1.5 dB. The solder bumps can position the photodiode accurately within /spl plusmn/1 /spl mu/m. A fiber guiding groove is used for alignment-free coupling between inter-modules. The coupling loss between the fiber and the waveguide is estimated to be 3.2 db with the deviation of about 0.1 dB. These techniques make OE-MCM's attainable.

Self-aligned high-quality total internal reflection mirrors

High-quality total internal reflection (TIR) mirrors are fabricated by a new self-aligned etch process using SiCl/sub 4/ reactive ion etching (RTE). The self-aligned etch process requires only a single SiO/sub 2/ mask layer without additional dielectric depositions and lift-off steps. The reflectivity of the TIR mirrors are measured by characterizing InGaAs-GaAs-AlGaAs strained-layer quantum-well heterostructure crank lasers that consist of crank-shaped ridge waveguides with two TIR mirrors and two cleaved facets. It is found that the self-aligned TIR mirrors have a very high reflectivity of 0.90 (0.46 dB/90/spl deg/ loss).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Lateral-mode discrimination in ridge waveguides by misaligned total internal reflection mirrors

Lateral-mode discrimination by misaligned total internal reflection (TIR) mirrors in multimode ridge waveguide structures is proposed. The effects of angular misalignment in TIR mirrors and index steps in ridge waveguides on the modal reflectivity is analyzed by a plane wave expansion method. The modal reflectivity of a high order mode decreases more rapidly than that of a fundamental mode as the angular misalignment of TIR mirrors increases. It is found that a fundamental mode can have high modal reflectivity (/spl sim/0.9) with significant lateral-mode discrimination over high-order modes if the ridge waveguides have large index steps.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Upgrade of triple-axis/four-circle diffractometer at PF-BL3A

Several new goniometers were installed on the triple-axis/four-circle diffractometer, SIN-1 at PF-BL3A to improve data acquisition ability and beam collimation. The most prominent improvement is development and installation of a new two-circle/one-linear goniometer, which was designed to mount various x-ray detectors, such as an imaging plate or a multielement solid-state detector to acquire diffraction and/or fluorescence data over a wide range of scattering angles. The new goniometer and the original four-circle goniometer have a common rotation center (i.e., the four-circle goniometer center). The new goniometer can be operated independently of the four-circle goniometer for a wide range of scattering angles. The new two-circle/one-linear goniometer consists of a tandem combination of a translation stage, η, and two-circle goniometers, κ and ξ, where these axes η, κ, and ξ correspond to polar coordinates (ρ, θ, φ), respectively. Other improvements such as development of a pair of total reflection mirrors for the collimator axis are also reported.

InGaAs-AlGaAs-GaAs strained-layer quantum-well heterostructure square ring lasers

The processing and optical characteristics of an InGaAs-AlGaAs-GaAs strained-layer quantum-well heterostructure square ring laser (4 /spl mu/m width and 50-/spl mu/m/side length) with two output waveguides and two narrow physical gap couplers are described. The ridges and the total internal reflection (TIR) mirrors of the square ring lasers are fabricated by two photolithographic steps with a single SiO/sub 2/ mask and planarized with polyimide such that the TIR mirrors are etched through the active region while the ridge waveguides are not. Single longitudinal mode operation is observed with a side mode suppression ratio of 20 dB. Asymmetric characteristics of emission spectra from the two output waveguides demonstrates that the square ring lasers operate in traveling wave modes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Monolithic InGaAsP-InP laser amplifier gate switch matrix

An InGaAsP-InP 2*2 laser amplifier gate switch matrix operating at 1.5 mu m with a fiber-to-fiber insertion loss of 3 dB is reported. The switch consists of passive waveguides for branching and recombining, monolithically integrated with laser amplifiers. The passive waveguides perform the signal routing, and the amplifiers provide gain/absorption in each path for on/off switching, achieving gain in the on state to compensate the losses. Dry-etched total internal reflection mirrors are employed as 90 degrees waveguide corner mirrors and also incorporated in the splitters in order to give a compact design. The on/off extinction ratio is >45 dB and the crosstalk is <-45 dB.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fresnel analysis of effective mirror reflectivity in folded-cavity in-plane surface-emitting lasers

Inside-cavity diffraction loss resulting from unguided regions and 45 degrees internal total reflection mirror(s) is an important issue for fabricating folded-cavity in-plane surface-emitting lasers. A Fresnel plane-wave decomposition method was applied to analyze this problem. The effective reflectivity of an angle-etched mirror was calculated for deviation of the etched angle and different lengths of the unguided region. The results offer design criteria for fabricating folded-cavity surface-emitting lasers as well as other devices with angle-etched facet(s) for surface normal light coupling.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fanning and photorefractive self-pumped four-wave mixing geometries

Results of recent experimental and theoretical investigations on the role of fanning in the operation of several popular photorefractive self-pumped FWM geometries, including the double phase conjugate mirror (DPCM), the ring oscillator, the semilinear mirror, the system of two coupled DPCMs, and the total internal reflection (TIR) mirror, are presented. The results can be divided into two groups. Geometries of the first group (the DPCM and the ring oscillator) have soft excitation thresholds. Geometries of the second group (the semilinear mirror, the system of the two DPCMs and the TIR mirror) have hard excitation thresholds. Geometries of the first group experience a noticeable influence of fanning only when the level of fanning of a single pumping beam passing through a crystal, is high. Geometries of the second group, such as the semilinear mirror, the system of two DPCMs, and the TIR mirror without fanning, are not self-starting.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

50 mW CW-operated single-mode surface-emitting AlGaAs lasers with 45 degrees total reflection mirrors

The authors report on the fabrication and testing of surface-emitting AlGaAs 3.5 mu m ridge lasers with etched mirrors and 45 degrees internal deflectors. The 45 degrees mirror coupling coefficient and the resulting threshold current penalty have been analyzed theoretically and experimentally. A surface-emitted optical power of 50 mW CW at 26 mA threshold current and external differential efficiency of 57% has been achieved in lateral fundamental-mode operation. The optical power density of 14 mW CW per micrometer ridge width is the highest reported to date and produces two-dimensional surface-emitting laser arrays of diffraction-limited beam quality suitable for optical storage applications.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design and fabrication of ridge waveguide folded-cavity in-plane surface-emitting lasers

A 45 degrees angled reactive ion etching combined with an in situ monitoring technique was used to fabricate ridge waveguide folded-cavity in-plane surface-emitting lasers. This laser structure, with two 45 degrees C angle-etched internal total-reflection mirrors and an epitaxially grown distributed Bragg reflector, is very promising for OEIC applications. Laser-structure design and laser fabrication are addressed. A continuous-wave threshold current of 8 mA, the lowest reported in the literature, was achieved on 3- mu m-wide, 350- mu m long devices.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Hard x-ray microprobe with total-reflection mirrors

A hard x-ray microprobe with a grazing-incidence total-reflection mirror system is developed. The optical system has a pair of elliptical mirrors arranged in a crossed mirror geometry (Kirkpatrick–Baez configuration) and forms demagnified images of an x-ray source. A focused spot size of 3.5 μm×4.8 μm is obtained at a wavelength of 2.3 Å. A focusing test with an x-ray source determined by a pinhole generates a finer microbeam. Preliminary experiments on scanning x-ray microscopy are performed using the focused x-ray beam.

Low-threshold InGaAs/GaAs strained-layer ridge waveguide surface emitting lasers with two 45° angle etched internal total reflection mirrors

A new type of in-plane surface emitting laser structure with two 45° mirrors has been demonstrated. The device is a ridge waveguide laser with total reflection mirrors etched at 45° to the plane of the active layer, having an epitaxially grown distributed Bragg reflector. Continuous-wave threshold current as low as 10 mA with 12% external differential quantum efficiency is achieved on a 5-μm-wide, 400-μm-long device.

Low-threshold CW operation of square-shaped semiconductor ring lasers (orbiter lasers)

The CW operation of square-shaped semiconductor ring lasers is demonstrated with a threshold current as low as 6 mA. The ring resonator consists of straight waveguides and four total reflection mirrors. The lasers are fabricated using Br/sub 2/ dry etching on an InGaAs/GaAs strained single-quantum-well graded-index separate-confinement heterostructure wafer. The low-threshold CW operation is due to the high differential gain of the wafer and the low-loss total reflection mirror.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Low-threshold InGaAs/GaAs strained-layer surface emitting lasers with two 45 degrees angle etched total reflection mirrors

An InGaAs/GaAs strained-layer IPSEL (in-plane surface emitting laser) structure with two 45 degrees dry-etched mirrors and a highly reflecting bottom quarter-wavelength stack is reported. It has a record low continuous-wave (CW) threshold current at 10 mA. The laser structure consists of a conventional double-heterostructure single-quantum-well (80-AA In/sub 0.2/Ga/sub 0.8/As/100-AA GaAs) laser structure on top of a quarter-wave stack (25 pairs of 695-AA GaAs/830-AA AlAs), which serves as a distributed Bragg reflector ( approximately 99%) after 45 degrees angle etching.