Marcelino G. Armendariz

Waveguide-to-fiber coupling using a second-order grating and an anamorphic binary optic

Historically, obtaining efficient coupling from single-mode waveguides in high performance GaAs modulator devices to single-mode fiber has been difficult. The reasons are; (1) the large modal mismatch between the elliptical waveguide output and the gaussian profile of the optical fiber; and (2) the large NA difference (0.9 for the waveguide in one direction) and 0.16 for fiber. Despite this difficulty, there exists a need for packaging devices with multiple fiber outputs, that have been gang-aligned, efficiently coupled, and hermetically sealed. (The latter item will be very important in automotive or aerospace applications.) Instead of trying to have fiber penetrate the package wall, the SNL approach to efficient coupling and hermeticity has been to allow light to penetrate the package wall. This has been accomplished by sending out the light normal to the waveguides and collecting it with a binary optic that focuses it on to a fiber outside the package. The optical design of this system requires that the beam be nearly collimated as it leaves the surface of the device. To accomplish this, a second-order grating was etched into a 200 /spl mu/m long section of an adiabatically expanded single-mode waveguide.<<ETX>>

A passive micromachined device for alignment of arrays of single-mode fibers for manufacturable photonic packaging

Summary form only given. This work provides a method of passive mechanical alignment of an array of single mode fibers to an array of binary optics. The technique employs the use of a micro-machined metal spring, that captures a vertical, pre-positioned fiber, moves it into accurate alignment, and holds it for attachment.

High-performance GaAs/AlGaAs optical phase modulators for microwave photonic integrated circuits

A high-performance high-speed optical phase modulator for photonic integrated circuit (PIC) use is described. Integration of these optical phase modulators into a real system (COMPASS) is also discussed. The optical phase modulators are based on depletion-edge translation and have experimentally provided optical phase shifts in excess of 60/spl degV/spl middot/mm with approximately 4 dB/cm loss while simultaneously demonstrating bandwidths in excess of 10 GHz.<<ETX>>

A passive micromachined device for alignment of arrays of single-mode fibers for hermetic photonic packaging-the CLASP concept

A micro-machined fiber alignment device, called the capture and locking alignment spring positioner (CLASP) has been fabricated. It uses a nickel leaf spring to passively capture vertical arrays of single-mode fibers with /spl sim/2 /spl mu/m accuracy.

Photonic integrated-circuit elements for phased-array steering systems

Progress will be presented regarding circuit elements to be eventually incorporated into a Photonic Integrated Circuit (PIC). Data from elements such as phase modulators and couplers will be reviewed. They have been developed employing ridge waveguides in MBE grown GaAs/AlGaAs material structures. A general approach to PICs will be discussed as well as their incorporation into optical frequency translation (OFT) modulation circuits for coherent optical systems. Detailed theoretical discussion of one, two, and four-arm phase-modulator-based OFT circuits is included.

Fabrication, packaging, and performance of VCSELs and photodetectors for space applications

Optocouplers are used for a variety of applications aboard spacecraft including electrical isolation, switching and power transfer. Commercially available light emitting diode- based optocouplers have experienced severe degradation of light output due to extensive displacement during damage occurring in the semiconductor lattice caused by energetic proton bombardment. A new optocoupler has been designed and fabricated which utilizes vertical cavity surface emitting laser (VCSEL) and resonant cavity photodetector (RCPD) technologies for the optocoupler emitter and detector, respectively. Linear arrays of selectively oxidized GaAs/AlGaAs VCSELs and RCPDs, each designed to operate at a wavelength of 850 nm, were fabricated using an airbridge contacting scheme. The airbridged contacts were designed to improve packaging yields and device reliability by eliminating the use of a polyimide planarizing layer which provided poor adhesion to the bond pad metallization. Details of the airbridged optocoupler fabrication process are reported. Discrete VCSEL and RCPD devices were characterized at temperatures between -100 degree(s)C to 100 degree(s)C. Devices were packaged in a face-to-face configuration to form a single channel optocoupler and its performance was evaluated under conditions of high-energy proton bombardment.

High-performance GaAs/AlGaAs optical phase modulators for microwave/photonic integrated circuits

High-speed high-performance optical phase modulators are being developed for use in a coherent Photonic Integrated Circuit(PIC) technology. These phase modulators are the critical component of a PIC program at Sandia National Laboratories targeted for microwave/millimeter-wave signal processing and control including phased-array antenna control. The primary design goals for these modulators are amenability for integration into PICs, high figure of merit (FOM) and large bandwidths allowing for operation at MMW frequencies. Depletion-edge-translation optical phase modulators have been selected as the device technology of choice due to their high FOM. These modulators unfortunately suffer from a large terminal capacitance which greatly limits speed. To overcome this problem, a distributed electrode design based on the use of slow-wave coplanar strips has been developed. Device design and measurements are presented in this paper.

CLASP (Capture and Locking Alignment Spring Positioner): a micromachined fiber auto-positioning device

This work provides a method of mechanical alignment of an array of single mode fibers to an array of optical devices. The technique uses a micromachined metal spring, which captures a vertical, pre-positioned fiber, moves it into accurate alignment, and holds it for attachment. The spring is fabricated from electroplated nickel, using photodefined polyimide as a plating mask. The nickel is plated about 80 micrometers thick, so that a large fiber depth is captured. In one application, the nickel springs can be aligned to optics on the back side of the substrate. This entire concept is referred to as CLASP (Capture and Locking Alignment Spring Positioner). These springs can be used for general alignment and capture of any fiber to any optical input or output device. Passive alignment of fiber arrays to +/- 2 micrometers accuracy has been demonstrated, with a clear path to improved accuracy.

Fabrication of high-performance GaAs/AlGaAs optical phase modulators for microwave/photonic integrated circuits

A high-speed distributed electrode phase modulator has been designed and fabricated. The processing of this device presented many challenges: (1) smooth rib waveguides etched to an accuracy of +/- 200angstroms; (2) polyimide planarization of 5micrometers step heights, with vias patterned as small as 1.6 micrometers ; (3) contact metalization with resistivities as low as 1 X 10-6(Omega) -cm2; (4) coplanar n and p gold contacts 2.5 micrometers thick, with a 0.5 micrometers gap between contacts; (5) ion- implantation to achieve both electrical and optical isolation. A brief description of how each of these processes have been accomplished will be presented. The epitaxial growth structure of this device will be discussed, including SEM cross-sections of the completed device.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Integrated test and package methods for integrated photonics

Arrangements of discrete photonic waveguide devices are currently being integrated to form circuits. These Photonic Integrated Circuits (PICs) require test methods that are adaptable as circuit size and complexity grows. Here, we describe tests used to characterize a GaAs/GaAlAs waveguide-based PIC being developed for phase-shift control in phased-array antenna applications. The various elements of the PIC include digital and analog waveguide modulators, light-guide splitters and combiners, turning mirrors, and input-output polarization-maintaining single-mode optical fibers. These basic elements are combined to perform higher-order functions such as optical frequency translation (single side-band suppressed carrier modulation), and phase shifting on multiple optical taps. Tests used to characterize the elements include optical loss, guided-wave modal characteristic, antireflection coating effectiveness, electro-optical (phase) modulation efficiency, electrical frequency response, and optical frequency translation. These tests are integrated with the fiber attachment and RF packaging sequence to construct working device prototypes. They are currently being applied to discrete components of the circuit, and will be adapted as the various parts are integrated.