Dennis G. Koshinz

Analysis of the tuning sensitivity of silicon-on-insulator optical ring resonators

High-quality-factor optical ring resonators have recently been fabricated in thin silicon-on-insulator (SOI). Practical applications of such devices will require careful tuning of the precise location of the resonance peaks. In particular, one often wants to maximize the resonance shift due to the presence of an active component and minimize the resonance shift due to temperature changes. This paper presents a semianalytic formalism that allows the prediction of such resonance shifts from the waveguide geometry. This paper also presents the results of experiments that show the tuning behavior of several ring resonators and find that the proposed semianalytic formalism agrees with the observed behavior.

Design and performance of a multiple element slab waveguide spectrograph for multimode fiber-optic WDM systems

A new type of compact ( < 7 cm2) multiple element slab waveguide spectrograph suitable for medium resolution fiber-optic wavelength division multiplexing (WDM) applica- tions in the 700 nm to 900 nm optical band is described. The spectrograph consists of a replicated diffraction grating formed on the convex edge of a multilayer glass-ceramic slab waveguide stack. The grating design, based on an aberration corrected derivative of the classic Rowland spectrometer, was first verified holographically, and then implemented by replication from a ruled master grating. A combination of thick-film solder glass glazing, lamination, optical finishing and grating replication was chosen to produce a multiple element spectrograph that enables accurate spectral referencing, and can be interfaced by a passive optical fiber array and detector array alignment proce- dures.

Demonstration of a Gb/S Transceiver with OTDR Built-in-Test for Avionics Local Area Networks

The motivations for development of an integrated BITed transceiver have been described in previous DASC papers (Beranek and Van Deven, 2005). One of the challenges in developing BIT capabilities in avionics local area networks is implementing the BITed transceiver functionality without degrading the transceivers electro-optic performance characteristics, or increasing its size, or changing its multi-source agreement (MSA) standard footprint format. We have successfully demonstrated the first prototype Gb/s fiber optic transceiver with integrated built-in test 10-cm resolution OTDR capability in a small-form-factor (SFF) package. This OTDR BITed transceiver operates at 850 nm with high output power and good electro-optic characteristics over 2 Gb/s. The 10-cm optical time domain reflectometry (OTDR) resolution requires the transceiver to have total rise time (tr ) and fall time (tf) less than 1 ns. This rise and fall time requirement indicates the intrinsic transceiver has to support a 2.5 Gb/s data rate

Wireless optical links for avionics applications

Recently there has been strong interest in wireless optical (WO) communication link applications in airplanes and avionics platforms for size, weight, power, cost, and electromagnetic interference (EMI) reduction. Wireless optical link has additional advantage of providing network security because the optical signal from wireless optical link is well confined within an airplane or avionics vehicle. In this paper we discuss some potential wireless optical link applications in commercial airplanes and the challenges in the implementation of wireless optical links for these applications. We will present our experimental results on using white LED (WLED), visible laser source and free-space small-form-factor (SFF) optical transceivers to demonstrate the viability of applying wireless optical links in avionics platforms.

Optical communications receiver array

One of the major challenges to free space laser communications and ladar is the impact of turbulence on beam propagation, one example of which is signal fading. These impacts can be exacerbated on airborne platforms by turbulence in the vicinity of the laser system aperture and the platform wake. There are a number of strategies to mitigate this, including adaptive optics, active flow control, and various dimensions of diversity: wavelength, polarization, temporal, and spatial diversity. In this paper we will discuss spatial diversity implemented in the focal region of optical telescopes. We will briefly compare this with other methods, describe results of requirements analysis of array features and optical configurations for various atmospheric turbulence states, and suggest several attractive configurations. We will also report on the design and test of one configuration, implemented in a prototype, and tested for noise performance, optical transmission, modulation bandwidth, and BER performance with our dynamic turbulence simulator. Early evidence shows significant BER improvements of several orders of magnitude at high turbulence fluctuation frequencies using this technique.

Hermetic fiber optic modules for avionics applications

In the past, Boeing had successfully developed and produced the hermetic ARINC 636 fiber optic transmitter and receiver modules for the PLANET System in the Boeing 777 commercial airplanes. These hermetic fiber optic modules had demonstrated over 4 millions aggregate flight hours with zero failure; the hermetic fiber seal technology is a key contributor to this outstanding reliability record. Recently, we have investigated failure mechanisms in commercial-off-the-shelf (COTS) hermetic mini-dil (dual-in-line) laser diode modules; and developed new hermetic fiber seal process for low cost mini-dil form factor packages. In addition, we are also developing cost effective hermetic multi-channel fiber optic array modules technology for aerospace applications.

Low cost, high data rate white LED (WLED) transceiver demonstration

We presented a low cost experimental WLED transceiver which is capable to perform wireless communication at 10 Mb/s in an airplane or a space craft physical environment. From the experimental results, we derived the operational requirements of the WLED transceiver with OOK NRZ modulation. These results demonstrate the WLED wireless communication link technology is viable for size, weight, power and cost reduction in future generation of airplanes and space vehicles.

Micro packaging of hermetic seal mini dual in line laser diode module for aerospace applications

Normally, reliable, reproducible, high-yield packaging technologies are essential for meeting the cost, performance, and service objectives for the harsh environment of space applications. This paper describes a new improved micro packaging method of hermetic seal mini-DIL (dual in line) laser diode module. The problem of using a softer solder resulted in failure mechanisms observed in the mini-DIL laser diode module based laser firing unit (LFU) for ordinance ignition of a missile system. These failures included: (1) failure in light output pulse power, (2) fiber pigtail damage inside the package snout which caused low LFU production yield. Our distinctive challenge for this project is the micro packaging of mini-DIL. For this package a new technique for the hermetic sealing using a micro-soldering process was developed. The process is able to confine the solder seal to a small region inside the snout near the fiber feed-through hole on the wall of the mini-DIL package. After completing the development, which included temperature and thermal cycling, X-rays analysis showed the new method had no fiber damage after the microsoldering seal. The new process resulted in 100% success in the packaging design and was granted a patent for the innovative development.

Low-cost high data rate white LED (WLED) transceiver development

Recently there has been strong interest in wireless white LED (WLED) communication link applications in airplanes and avionics platforms for size, weight, cost, and electromagnetic interference (EMI) reduction. Wireless WLED link has additional advantage of providing network security because the optical signal from WLED link is well confined within an airplane or avionics vehicle. In this paper we discuss and analyze commercial-off-he-shelf WLED design and color measurement results. An experimental implementation of a low cost WLED transceiver which shows error free freespace operation at 10Mb/s is successfully demonstrated. The feasibly of implementing free space optical link which meets both lighting and communication requirements using WLED array is analyzed by mathematical modeling using MATLAB simulation technique.

Hermetic fiber optic modules for aerospace

The authors presented the challenges to produce hermetic fiber optic module for flight critical avionics applications. We have provided viable approaches to produce hermetic fiber optic modules for different aerospace platform applications.