Huan-Wun Yen

ARPA analog optoelectronic module program: packaging challenges for analog optoelectronic arrays

This paper describes the packaging challenges associated with array-based transmitters and receivers used for analog fiber-optic links. The optoelectronic modules are being developed under an ARPA Analog Optoelectronic Module TRP. The paper will focus on the development of optoelectronic array modules using silicon waferboard technology for application to personal communication systems.

rf optoelectronic transmitter and receiver arrays on silicon wafer boards

Silicon waferboard technology based on etched and deposited passive-alignment features has been applied to the fabrication of optoelectronic transmitter and receiver arrays for rf applications. Using silicon waferboards, we have aligned both 1 by 4 buried-heterostructure laser arrays and 1 by 4 PIN photodetector arrays to optical fiber ribbons. Besides serving as mechanical carriers and alignment guides, the silicon wafers can also be used as rf or microwave substrates. We introduce rf-optoelectronic receiver arrays based on such enhanced silicon waferboards.

System design and performance of a wideband photonic array antenna

Presented in this paper is an overview of the development of a wideband photonic array antenna. The presentation will focus on the performance of a unique L-band 24 X 4 element conformal array, supported by a photonic true-time-delay beamforming network. A 2-ns pulse was injected into the system and the round trip impulse response was measured to demonstrate the arrays 550 MHz instantaneous bandwidth.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Photonics for phased-array antennas

In this paper, we discuss the applications and also several important system issues: insertion loss, noise figure, dynamic range and cost relating to photonics for wideband phased array antennas. This discussion is based on the work that we did on an L-band Optical Control of Phased Array Project funded by DARPA/Rome Lab. The antenna has been delivered to Rome Lab for further demonstration.

Anomalous multiplication in Hg0.56Cd0.44Te avalanche photodiodes

We quantitatively study the electric field distributions in Hg0.56Cd0.44Te avalanche photodiodes recently reported for use in the 1.6–2.5 μm wavelength region using a two‐dimensional solution of Poisson’s equation. It is found that, contrary to previous reports, there is no evidence for large uniform avalanche gain in these diodes. Furthermore, to first order, it is shown that the ionization rate ratio of electrons to holes in the diodes demonstrated to date is on the order of unity. Hence, it is not expected that the present diodes will lead to low noise operation superior to Ge or In0.53Ga0.47As/InP avalanche photodetectors.

Array transmitters and their application in rf photonics systems

We describe the design of single frequency array transmitters and their application in RF-photonic systems. In addition, we present an array-based packaging technology that is based on passive-alignment with Si-waferboards.

Analog OE module development TRP status report

A Defense Advanced Research Project Agency (DARPA) sponsored consortium combines expertise in .military and commercial systems (Hughes, Boeing, GTEL), optoelectronic (OE) manufacturing (Ortel, UTP, Atx Telecom), and DoD applications (MiT Lincoln Lab, NCCOSC RDT&E Division) and leverages collective investments through technology transfer among the partners to develop user friendly and affordable analog OE modules. The availability of such modules wifi accelerate the pace of optoelectronic module insertion into anaiog systems and realize the vast market potential and national defense payoffs. Low cost transmitter and receiver modules, transmitter and receiver arrays, OEICs, enhanced and linearized electro-optic modulators, diode pumped solid-state lasers and 16x16 photonic switch arrays have been developed and tested. Introduction The global telecommunications infrastructure, which is interconnected by thousands of wireless RF and microwave links, as well as fiber optic trunk lines and networks, combines analog and digital communications. There are significant military and commercial applications which will be enabled by low cost, rugged analog OE modules for RE transmission, reception, and interconnection over optical fibers. These applications include: (1) Broadband Distribution Networks Future fiber based broadband networks will offer a large menu of interactive video, voice, and data services to residential and business customers. (2) Wireless Cellular and Personal Communications -Analog fiber optic links provide microcell and picocell antenna remoting. Military wireless systems and satellite-based global interconnection hubs will have analog/digital fiber optic remoted OE interfaces. (3) Wideband Phased Arrays Wide bandwidth optically steered arrays wifi solve timely military surveillance and tracking problems with low observables, tactical ballistic missile defense, and strategically re-locatable targets and threats. (4) Military and Commercial Avionics Military avionics networks (Pave Pace-like architecture) wifi maximize reliability and minimize cost through the use of common module processors, receivers, and apertures in an Integrated Sensor System enabled by a switched analog optical network. Commercial airliners with fiber-based information management networks that handle both digital and RF signals, provide a spectrum of interactive information 284 ISPIE Vol. 2844 O-8194-2232-O/961

Silicon wafer board alignment of laser arrays to single-mode optical fiber for analog optoelectronic module applications

6.OO services to passengers, including multi-channel, high-quality video, games, telecommunications and personal computing. (5) Optical Sensing and Measurement a remotely located and fiber addressable EO modulator serves as a wideband electro-magnetic field sensor, and fiber optic delaylines can be used for built-in testing of complex radars. Despite the vast market potential and national defense payoffs outlined above, the pace of OE module insertion into analog systems has been slow. The reasons are high component cost and unfavorable environmental limitations in comparison with competing technologies. The objective of the Analog OE Module Development Technology Reinvestment Program (TRP) is to eradicate these module insertion barriers. We have formed a consortium under DARPA sponsorship that combines military and commercial systems expertise (Hughes, Boeing, GTEL), OE manufacturers (Ortel, Uniphase Telecommunications Products, ATx Telecom Inc.), and Government-funded laboratories (MIT Lincoln Lab, NCCOSC RDT&E Division), and leverage our individual investments through technology transfer among the partners to develop user-friendly and affordable analog OE modules. Table 1. OE Modules targeted for development Module Type Content Characteristics Developers Low-cost, Single-Channel Transmitter/Receiver Modules DFB Laser Module PIN Photodiode Module 0.01 2.5 0Hz Direct Modulation Ortel, MITLL Multi-Channel Transmitter/Receiver Modules Diode Laser Array OEIC Receiver Array 0.01 2.5 0Hz Direct Modulation HRL, GTEL, MIT-LL Single and Multi-Channel High Performance Transmitter/Receiver Modules Linear Modulator & Array OEIC Receiver Array Compact Solid-State Laser 0.1 18 GHz External Modulation >110 dB/Hz D.R. HRL, UTP, MIT-LL, ATx Switch Array Module LiNO3 Switch Array Optical Fan-in/out Circuits 16 x 16 Array Low-Loss & Low-Crosstalk Boeing, UTP As shown in Table 1 , four types of OE modules are targeted for development to meet the anticipated market requirements: (1) A pair of low cost, connectorized single channel transmitter and receiver modules that cover the frequency range of 0.01 to 2.5 GHz, using direct modulation of semiconductor lasers. (2) A pair of multi-channel transmiuer and receiver modules that employ array semiconductor lasers and photodetectors employing silicon waferboard packaging. (3) A pair of single and multi-channel high performance transmitter/receiver modules using external modulation techniques to meet wide bandwidth (up to 18 GHz) and high dynamic range (>1 10 dBIHzV3) requirements. The optical source that feeds the modulator will be a compact diode-pumped solid-state laser. The receivers are SPIE Vol. 2844 / 285 wideband optoelectronic integrated circuits (OEICs). (4) A 16 x 16 optical switch array module with integrated bias and switching control electronics. The resulting four module types will form the nucleus of product lines with ready application to military and commercial systems at significantly reduced costs and increased reliability. An important part of the program is the analog OE module application studies to identify high payoff applications, to define the required module characteristics and to develop a productization plan. A finding of the application studies is that military systems tend to require wide bandwidth, high dynamic range, and a large diversity of operating frequency bands. In contrast, commercial applications tend to bunch together around 1 2 GHz and below. The instantaneous bandwidth is also quite modest. This bi-modal distribution makes it difficult to have across the board dual-use module specifications. Furthermore, typical commercial applications have large volumes while any given military application usually has only a small quantity potential. One approach is to make modules destined for military applications versatile enough to cover a large number of systems thereby building up the volume base. In addition to developing OE module packaging and manufacturing technologies, demonstrations of the developed modules in real system scenarios are also planned. In addition to validating the design, the performance data collected and analyzed during the demonstration tests will be used to refme our module packaging and manufacturing processes. This two-year intensive technology development program is jointly funded by DARPA and members of the consortium. In the following paragraphs, we will give brief descriptions of the characteristics of several modules that have been developed and tested during the course of the program. Low-Cost Single-Channel Transmitter/Receiver Modules The goal of the low-cost transmitter and receiver modules development is to as nearly as possible match the costs of digital modules, yet maintain most of the key operating characteristics of analog links assembled from available high performance laser modules and photodiode modules. Low-cost connectorized optoelectronic devices and transceiver modules developed by Ortel are shown in Figure 1. The design specification is for a link with a carrier-to-noise ratio, CNR> 65 dB and Carrier-to-Intermod ratio, C/I> 50 dB, both over a 30 kHz bandwidth. The corresponding measured values are CNR =69.2 dB and C/I = 66.6 dB and are well within the specifications. This performance is achieved by incorporating a high dynamic range DFB laser chip, improved optical design that reduced optical reflections and RF impedance matching circuits. The laser-welded connectorized 286 / SPIE Vol. 2844 packaging is amenable to low cost reliable manufacturing as well as making the modules user friendly. The capability of operating at frequencies up to 3.5 GHz is expected to satisfy most commercial applications in broadband networks, antenna remoting and infrastructures for cellular and wireless PCS networks. Indeed, the modules were used in a successful field demonstration of an in-building cellular communication system conducted by GTEL in their Austin, TX TeleGo sales office. Cellular radio signals were transported to and from the roof of a building using a fiber optic link assembled from the modules to provide service to users inside the building who were otherwise blocked from coverage as a result of shading, wall losses, etc. Increased product sales have been attributed to the installation of this field-trial test system. Some applications, such as those encountered at the cellular phone base stations where two-way cormnunications between the station and remoted antenna sites must be maintained, require a large number of co-located transmitters and receivers. In addition to reduced size and power consumption, it is more cost effective to use arrays of lasers and detectors packaged in one or two modules as opposed to having multiple individually packaged transmitter and reciver modules. Diode laser array and photodetector chips are SPIE Vol. 2844 / 287 Developed by Ortel Used by GTEL in Cellular Te!ephone Field Trial & PCS Demo Used by MIT-LL in UHF Antenna Remoting Demo

Development of an optically controlled phased array

1 Laser-Welded, Connectorized Module 2-Channel Transc&ver Module Multi-Channel Transmitter/Receiver Modules used in constructing these multi-channel modules. A 4-channel receiver array module developed by Hughes and GilL is shown in Figure 2. The chips are mounted on a silicon waferboard where alignment stops and fiber holding grooves have been prefabricated. The assembly process involves only passive alignment techniques to mount the laser and photodetector array chips. A multi-fiber connector is used to achieve optical mating with a single connection op

Status of optically controlled phased-array development

This paper describes the development of laser transmitter arrays for analog optoelectronic link applications up to 2 GHz. These modules have been developed in an attempt to utilize passive assembly and alignment operations for the purpose of reducing costs. To this end, silicon waferboard integration platforms and semiconductor laser arrays have been fabricated with special alignment features that allow passive assembly of flip-chip laser arrays to single-mode optical fiber arrays.