Greg E. Blonder

Glass waveguides on silicon for hybrid optical packaging

Work on deposited glass waveguides on silicon to form waveguides and filters is reviewed. The choice of these particular waveguides makes sense only as part of a consistent approach to optoelectronic packaging. Hybrid optical packaging on silicon (HOPS) is described and briefly compared with other techniques. For these packages, two waveguides were developed: a tight mode waveguide with a silicon nitride rib core for matching a semiconductor laser and a loose mode waveguide with a phosphosilicate glass core for matching an optical fiber. >

Measurement of very low-loss silica on silicon waveguides with a ring resonator

The loss in phosphorus‐doped silica on silicon waveguides was accurately measured using a 6‐cm‐diam ring resonator, by recording the transmission of a narrow linewidth external‐cavity laser through the resonator as a function of temperature. A finesse of 45 and resonance width of 24.2 MHz were obtained, indicating guide loss of 2.6 dB per meter, which is the best result thus far measured for these waveguides. The shift in the modes with temperature was measured in the temperature range 30–120u2009°C and found to be close to 1/8 A/deg.

High index contrast mirrors for optical microcavities

A new technique for constructing multilayer dielectric mirrors is described that results in high reflectivities with only two or three dielectric layer pairs per mirror. These structures are obtained by selectively etching layered AlxGa1−xAs material grown by molecular beam epitaxy and then replacing the etched regions with acrylic resin or air. A thin optical cavity produced by this technique is demonstrated with mirror reflectivities near 96%. These techniques allow the fabrication of lasers, light‐emitting diodes, or optical switches with high contrast ratio mirrors on both sides of an optically active region in order to enhance output coupling, lower laser thresholds, and increase modulation rates.

1.54 μm room‐temperature luminescence of MeV erbium‐implanted silica glass

MeV erbium implantation doping of 10‐μm‐thick silica glass films on a Si substrate is studied with the aim of incorporating the rare‐earth dopant on an optically active site in the silica network. As‐implanted samples (3.5 MeV, 5×1015 Eru2009ions/cm2) show a strong luminescent transition at a wavelength of 1.54 μm, even at room temperature, corresponding to an intra‐4f transition of Er3+. Thermal annealing at temperatures up to 900u2009°C increases the luminescence intensity by a factor of 2 to 3. For temperatures above 1000u2009°C the intensity decreases drastically as a result of Er precipitation. The lifetime of the excited state is in the order of 10 ms. Photoluminescence studies at 4.2 K are used to identify implantation‐induced damage.

A silicon-based moving-mirror optical switch

A multimode 2*2 optical switch made from chemically micro-machined silicon piece parts is described. This switch uses microlenses, aligned to fibers by a silicon base, to expand the optical beam and relax alignment tolerances and a pivoting silicon mirrors as the switching mechanism. The moving mirror switch meets or exceeds all the requirements for FDDI applications. The switch loss is typically 0.7 dB and operates at 5 V and 30 mA. The switch insertion/deinsertion time is less than 10 ms, and the optical interruption time is less than 1 ms. The switch design, which minimizes alignments in fabrication and provides for z-axis assembly and the low cost of the high precision piece parts contribute to making this a low-cost switch to manufacture. >

A self-aligned optical subassembly for multi-mode devices

A completely self-aligned optical sub-assembly is described that meets the optical alignment tolerances needed for low-loss LED and PIN photodiode OSAs. Solder reflow aligns the optical device (LED or PIN photodiode) to a silicon header, which is mechanically aligned to a silicon fiber stub with fiducial cavities and alignment spheres. This assembly is in turn mounted in a plastic ferrule. Devices made using this alignment scheme have demonstrated losses as low as 0.5 dB relative to a butt-coupled fiber measurement. >

Optical recording applications of reactive ion beam sputter deposited thin‐film composites

Metal/metal oxide and metal/metal nitride thin‐film composites (metal=In,Cu) have been prepared by reactive ion beam sputter deposition (RIBSD) and incorporated into antireflection trilayer structures. The RIBSD technique produces thin, homogeneous films whose complex index of refraction can be reproducibly varied. We find the In/InOx composite to have extremely favorable characteristics for optical recording, such as an optimized 0.25‐nJ threshold sensitivity, a reflection contrast ratio higher than 60, and good environmental stability. Repeated write‐erase cycles have demonstrated a fast reversible phase change which occurs without noticeable degradation in reflection contrast.Metal/metal oxide and metal/metal nitride thin‐film composites (metal=In,Cu) have been prepared by reactive ion beam sputter deposition (RIBSD) and incorporated into antireflection trilayer structures. The RIBSD technique produces thin, homogeneous films whose complex index of refraction can be reproducibly varied. We find the In/InOx composite to have extremely favorable characteristics for optical recording, such as an optimized 0.25‐nJ threshold sensitivity, a reflection contrast ratio higher than 60, and good environmental stability. Repeated write‐erase cycles have demonstrated a fast reversible phase change which occurs without noticeable degradation in reflection contrast.

Si-based laser subassembly for telecommunications

Silicon is used as a packaging medium to integrate a laser, lenses, and a back facet monitor into a compact sub-assembly suitable for low-cost laser packages. The sub-assembly consists of separate laser and detector/optics submounts made of silicon. Only a single axis alignment is required during assembly to align the lenses (300 micrometers diameter sapphire spheres) with the laser active area. In a single lens configuration, the integrated sub-assembly had 25% coupling efficiency into single-mode fiber compared to 30% maximum coupling efficiency achieved on the optical bench. Coupling efficiencies of the integrated sub-assembly to 50 micrometers multi-mode fiber greater than 70% were achieved. The effective numerical aperture of the back facet monitor in the sub-assembly was greater than 0.7.

An Improved Interferometric Pressure Optrode

This paper describes a fiber optic pressure transducer intended for use in biomedical applications. The sensing element, or optrode, is an interference cavity or etalon (essentially a Hadley - Dennison filter) formed mainly of glass, which is mounted at the end of a single optical fiber. This construction offers several advantages over earlier transducer designs based on similar principles.

Trends In Manufacturing Effectiveness

Compared to the rest of the world, the United States has stagnated or fallen behind in its investment in research and new manufacturing capabilities. Many are worried that this lack of resolve will further erode our standard of living and ability to compete. Unfortunately, direct measures of research and manufacturing productivity are rarely available or trustworthy. We will discuss some of these trends, and try to draw reasonable conclusions for where we are and where we are going.