Modest M. Oprysko

Passive laser-fiber alignment by index method

A method for packaging a laser-fiber module was explored in which the critical laser-fiber alignment is carried out not with the usual active means, i.e., with the laser activated, but by a passive method based on the registration principles of photolithography. The method relies on an index scheme in which fiducial marks are lithographically placed on the laser chip and on a fiber carrier. At 850 nm, using the index technique with cleaved multimode fibers, it was possible to achieve the same laser-fiber coupling efficiency as attained by active alignment; with cleaved single-mode fibers about 80% of the active-alignment coupling efficiency was achieved.<<ETX>>

Packaging of high-density fiber/laser modules using passive alignment techniques

A novel method for packaging a laser-fiber module is explored in which the critical laser-fiber alignment is carried out not with the usual active means, i.e., with the laser activated, but by a passive method based on the registration principles of photolithography. The novel method relies on an index scheme in which fiducial marks are lithographically placed on the laser chip and on a fiber carrier. At 850 nm, using the index technique with cleaved multimode fibers, it has been possible to achieve the same laser-fiber coupling efficiency as attained by active alignment; with cleaved single-mode fibers about 80% of the active-alignment coupling efficiency was achieved. Details of the novel index-alignment method are discussed, and a brief description of an improved computer-controlled version of the apparatus is given.<<ETX>>

Polymeric Optical Waveguides

The present work describes the characterization of internally developed epoxy ridge optical waveguides which exhibit low propagation loss (0.3 dB/cm at 1.3 μm), high environmental stability (low sensitivity to moisture), have smooth walls (100 nm sidewall roughness), and high temperature stability (275°C). The techniques used to fabricate these waveguides are compatible with the planar processes used in the manufacture of high performance electronic packages.

Low-cost fabrication of optical subassemblies

The optical subassembly is a major contributor to the cost of a fiberoptic computer data link. A technology for low-cost fabrication of optical subassemblies is described, with emphasis on the transmitter subassembly. A factor of three cost reduction is achieved by limiting the parts count to only three: a laser or receiver chip packaged in a TO-can, a plastic housing, and a plastic aspheric lens; and by employment of a fast, automated active-alignment and subsequent fixing technique. Key enabling features include the rise of precision injection molding of specially chosen plastics, an aspheric lens design which permits wide positional variations in the axial direction, and curing of a fast setting epoxy through the use of RF power. A tool was constructed which produced subassemblies at high yield having satisfactory performance.

Overview of optical interconnect technology

High performance computers have been striving for higher speed better connectivity and higher throughput since their inception. Continuous advancement in the performance of active devices is placing an increasingly heavier demand on passive interconnects. This paper reviews optical interconnect technology in light of recent developments and suggests opportunities in datacom applications.

Total internal reflection mirrors fabricated in polymeric optical waveguides via excimer laser ablation

Excimer laser (248 rim) ablation has been used for rapid large area defmition of total internal reflection (TIR) mirrors in thick (50 tim) polymeric optical waveguides. The mitrors are capable of reflecting light into or out of the waveguide plane with a loss of less than 1 dB

Propagation properties in short lengths of rectangular epoxy waveguides

The propagation loss and beam spreading in large-core epoxy ridge waveguides on a glass substrate at wavelengths ranging from 630 to 1550 nm have been measured. At the intermediate wavelengths, a loss floor of 1.2 dB/cm is observed which is caused by inclusions and wall imperfections. The theoretical and experimentally determined equilibrium numerical aperture is 0.65 and 0.29 and the modal dispersion is 5.1 and 1.0 ps/cm, respectively. The discrepancy is due to strong scattering. The scattering does not give rise to any noticeable mode mixing. The epoxy waveguides also provide a rapid filling of the modes which is attractive for modal noise suppression.<<ETX>>

Laser microfabrication of optical circuits in LiNbO3

Optical waveguides have been fabricated in x‐cut LiNbO3 by direct laser patterning of ‘‘spin‐on’’ organometallic inks. The technique has been used to repeatedly and rapidly produce single‐ and multimode waveguide structures, such as lines, y branches, and couplers. In addition, an entirely laser‐delineated Mach–Zehnder interferometric modulator has been fabricated.

Future Beam-Controlled Processing Technologies for Microelectronics

Beam-controlled processes that utilize photons, electrons, ions, and molecules have become essential in the fabrication of microelectronics. These processes are required for the deposition, patterning, etching, and characterization of semiconductor, packaging, and processing-related materials that form the basis of the integrated circuit. Fabrication techniques demand an increasing precision as the physical size of the device structures shrink to submicrometer dimensions. In this article, selected examples of beam-controlled processes expected to be important in the microelectronics industry are described. The continued rapid advances in microelectronics technology that underlie the electronic information-processing industry require the continued development and refinement of these new techniques.

Optical waveguides in the computer environment: a packaging perspective

Polyimides have been experimentally studied for their potential application in optical interconnection networks. A total of nine commerically availables polyimides were evaluated in the form of planar slab optical waveguides. Analysis included measurement of optical properties such as transmission spectra, refractive index and loss. From this preliminary evaluation, four polyimides emerged as promising for application as channel optical waveguides. With these materials, multimode channel waveguides were fabricated with one of three methods, laser writing by thermal curing, laser writing with visible radiation in photosensitive polyimide and photolithography by contact printing, also in photosensitive polyimide. All three methods were relatively successful, yielding uniform, straight channels. Loss measurements suggest that laser writing by thermal curing has the potential to form waveguides with the lowest loss. However, attenuation in all cases was relatively high, typically 5 - 10 db/cm at 633 nm.