Samples of PMMA [Poly-(Methyl-Meth-Acrylate)] were modified by ionizing radiation (especially UV-radiation) in order to generate regions of increased refractive index. These waveguiding structures were used to build o...
详细信息
ISBN:
(纸本)0819418994
Samples of PMMA [Poly-(Methyl-Meth-Acrylate)] were modified by ionizing radiation (especially UV-radiation) in order to generate regions of increased refractive index. These waveguiding structures were used to build optical power splitters and optical polarizers simply by varying the exposure time. The refractive index profile and the variation in thickness of the waveguides for different exposure times were observed. Also the cut-off-wavelength and the spectral absorption behavior for different exposure times were measured. The compaction at the surface was used to build up diffraction gratings with grating constants of 4 micrometer to 20 micrometer. By annealing the samples the diffraction efficiency was increased.
Recently the laser microbeam instrument has been used for wider applications in biological science and medicine. A key problem of the laser microbeam instrument is designing the laser focusing system for getting a foc...
详细信息
ISBN:
(纸本)0819418994
Recently the laser microbeam instrument has been used for wider applications in biological science and medicine. A key problem of the laser microbeam instrument is designing the laser focusing system for getting a focal spot size of less than 1 micrometer. This paper presents a new laser focusing system which is composed of a spatial filter and an 80× focusing objective lens. The 80× focusing objective lens was designed as a double reflective sphere type. Using this focusing system, the laser microbeam instrument has gotten a focal spot size of less than 0.5 - 1 micrometer. The focal spot size depends on the pinhole diaphragm diameter of the spatial filter. Different pinhole diaphragm diameters could produce different focal spots that are given in the end of this paper.
In this article we have designed a new type of prismatic telescope which can be used to amplify the divergence of the laser beam. Theoretical analysis and computer analog indicate that the divergence multiplication fa...
详细信息
ISBN:
(纸本)0819418994
In this article we have designed a new type of prismatic telescope which can be used to amplify the divergence of the laser beam. Theoretical analysis and computer analog indicate that the divergence multiplication factor is independent of the distance between the prismatic telescope and the waist of the laser beam, and the original divergence of the laser beam in 20 mrad, the laser beam as it passes through the prismatic telescope is still Gaussian beam. We have made and measured the prismatic telescope and found the result agrees with our theoretical analysis.
Intracavity contacted vertical-cavity lasers are a class of index-guided surface-emitting lasers which use thin p-type and n-type layers within the optical cavity to supply current to the active region. The design all...
详细信息
ISBN:
(纸本)0819417467
Intracavity contacted vertical-cavity lasers are a class of index-guided surface-emitting lasers which use thin p-type and n-type layers within the optical cavity to supply current to the active region. The design allows the use of two ring contacts on the same surface, top or bottom emission, and semi-insulating substrates. A dielectric aperture is used to provide both current constriction and optical confinement. The models used to design the laser's continuous wave characteristics are discussed and the calculated characteristics are compared with experimental measurements. The microwave modulation response of lasers of varying diameter has been measured with wafer-level probing techniques. The very high modulation efficiency of the lasers, up to 5.7 GHz/√mA, shows good agreement with theory. The analysis indicates the directions and challenges for the realization of very high-speed, low-power surface-emitting lasers.
We have developed a hybrid optoelectronic circuit to demonstrate a free-space optical interconnect in a CMOS chip. Discrete GaAs- based optical devices are hybridly integrated with a 0.8 μm CMOS chip fabricated by a ...
详细信息
ISBN:
(纸本)0819417475
We have developed a hybrid optoelectronic circuit to demonstrate a free-space optical interconnect in a CMOS chip. Discrete GaAs- based optical devices are hybridly integrated with a 0.8 μm CMOS chip fabricated by a MOSIS foundry. The CMOS chip consists of two separate digital modules, an ALU and a ROM, communicating via a pair of optical interconnects. Each interconnect consists of a CMOS laser driver that converts full CMOS logic-level data into a suitable laser drive current, a laser-photodetector pair, and a CMOS transimpedance amplifier that converts a photocurrent from the photodetector into logic-level data. An on-chip clock is used to time the serialization and deserialization of 4-bit words of data across each interconnect at a data rate of 40 Mb/s. In order to account for limitations of the hybrid design as well as process variations, pads are provided for off-chip clock signals to override the built-in clock and therefore operate the interconnect at a transmission rate different from the design value. Each laser-photodetector pair is fabricated from a single laser structure epitaxially grown on semi-insulating GaAs substrate. Similar to a laser-photomonitor arrangement, a dry etch is used to divide the laser structure into a separate laser and photodiode. This device is then hybridly integrated with the CMOS chip to implement the proof-of-principle free-space optical interconnect. Experimental results for the optical elements and simulation results for the CMOS design are presented to demonstrate the operation of the chip.
Development work is underway on a high current, mildly relativistic, L-band klystron source. The intense beam used in this tube presents unique design complications for the output circuit. Various considerations are d...
详细信息
ISBN:
(纸本)0819419168
Development work is underway on a high current, mildly relativistic, L-band klystron source. The intense beam used in this tube presents unique design complications for the output circuit. Various considerations are discussed such as the trade-offs between beam potential and kinetic energies, optimum shunt impedances, and advantages of discrete versus distributed circuits. Three output circuit designs are presented. A description of the experimental hardware is given along with power extraction results from two output circuits.
The optical lithography is extending its life by combining high numerical aperture (NA) optics and shorter wavelength. The shorter wavelength lithography has required the new developments of related technologies. In p...
详细信息
ISBN:
(纸本)0819417882
The optical lithography is extending its life by combining high numerical aperture (NA) optics and shorter wavelength. The shorter wavelength lithography has required the new developments of related technologies. In particular, DUV resists require an entirely different resist chemistry. Much progress has been demonstrated in the field of transparent chemically amplified resists with high sensitivity. However, this DUV lithography (λ = 248 nm) has been delayed for mass production due to their limitations, such as (i) delay time effects, (ii) high cost ownership due to expensive resist materials and laser maintenance, and (iii) critical dimension (CD) variation over topography caused by multireflection of topographic features. On the other hand, i- line lithography (λ = 365 nm) has apparently been applied to 64M DRAM of 0.35 μm design rule, and attempted to 0.30 μm technology which corresponds to 2nd generation 64M DRAM or 1st generation 256 M DRAM. It might be achieved by combination of off-axis illumination (OAI), phase shift mask (PMS) and advanced resist process technique of i-line lithography. Therefore, i-line lithography can be more practical method rather than DUV lithography for the mass production. In this paper, we have optimized the i-line lithographic techniques for the various pattern shape and density for 0.30 μm design rule. Optimum duty ratio was tried to find for line and space, contact hole patterns. The basic rule is to keep the minimum Cr width over 0.30 μm mask. OAI have been applied to get higher contrast of line and space, and even contact hole patterns, and achieve good pattern fidelities of island patterns. By the implementation of OAI, process latitudes were greatly improved compared to that of conventional techniques. In order to optimize the process over the actual topography, optimum numerical aperture (NA) and aperture of the OAI were selected. In conclusion, 0.30 μm design rule device was successfully fabricated by optimizing the advanc
Backward-wave oscillators driven by high current relativistic electron beams are capable of producing high power coherent radiation in the ceentimeter and millimeter wavelength regimes. However, the efficiency of thes...
详细信息
ISBN:
(纸本)0819419168
Backward-wave oscillators driven by high current relativistic electron beams are capable of producing high power coherent radiation in the ceentimeter and millimeter wavelength regimes. However, the efficiency of these devices is usually limited to 15-20% when a homogeneous slow-wave structure is used. Utilizing a two-section slow wave structure, where the spatial period of the second section is larger than that of the first section, a BWO efficiency of greater than 50% was calculated. A conceptual design of a high efficiency S-band backward-wave oscillator driven by a 500 kV, 5 kA electron beam has been developed and analyzed.
The proceedings contain 45 papers. The topics discussed include: opticaldesign of a two-mirror asymmetrical reshaping system and its application in superbroadband color center lasers;refractive indices of liquids in ...
The proceedings contain 45 papers. The topics discussed include: opticaldesign of a two-mirror asymmetrical reshaping system and its application in superbroadband color center lasers;refractive indices of liquids in the infrared spectral region;stability of the optical properties of abnormally dispersive liquids;optical performance of axial gradient and aspheric surface lenses: study and analysis;multilevel Fresnel zone lenses capable of being fabricated with only one binary mask;computer-generated diffractive optical elements for optical interconnections: design and validation codes;and nonphotolithographic fabrication of large computer-generated diffractive optical elements.
暂无评论