Flora Ho

Ultralow-Cost Optical Transceiver Modules Based on Leadframe Plastic-Package Technology

We have developed ultralow-cost optical transceiver modules based on leadframe (LF) based plastic package. The vertical-cavity surface-emitting laser (VCSEL) based transmitter shows stable optical power output with a variation of less than 0.2dB over a wide temperature range from -40degC to +105degC. Optical output eye-diagrams at 50Mbps show excellent timing performance with low jittering less than 150ps. The extinction ratio is maintained around 8dB from -40degC to +105degC. The transmitter modules show excellent reliability data including 1000 cycles of temperature cycling from -40degC to +125degC. On the receiver side, we have fabricated GaAs metal-semiconductor-metal photo detectors (MSM-PD). The MSM-PD has a lower capacitance per unit area compared to conventional pin-photodiodes. The capacitance of the MSM-PD with diameter 250mum at different bias voltages is around 0.8pF at bias voltages from 0.5V to 10V. The MSM-PD receiver shows a wide open eye diagram at 3.2Gbps. From the bit error rate curve of the receiver we interpolate a sensitivity of better than -18dBm for error rate of 10-12. We have demonstrated high speed transmission at 1.25Gbps over 10m PCS fiber with our VCSEL transmitter and MSM-PD receiver. For lower data rates and extended reach applications in low cost POF systems, we have developed Green-LED transmitters operating at 520nm wavelength. For a 40m POF system we obtain a 3.1dB wider power budget margin over the operating temperature range from 0degC to 85degC compared the red LED transmitters. The 10Mbps optical output waveforms are wide open at 25degC and 85degC

Small size fiber optic modules based on plastic packaging technology for gigabit speed video link applications

We have developed small size fiber optic modules based on plastic packaging technologies for PCS fiber systems. The transmitter contains a vertical-cavity surface emitting laser (VCSEL) operating at 850nm wavelength, an electronics driver chip, and some passive components. The package is a low cost leadframe style for through-hole or surface mounting (SMT). The SMT fiber optic transmitter is compatible with a reflow soldering process in an infra-red oven of 250degC peak temperature. With a specially designed heat shield the prototype shows a stable optical alignment performance before and after the reflow soldering. The output power of the transmitter is limited to 0.7mW to meet eye-safety class I requirements. The transmitter has an integrated coupling optics to provide loose alignment tolerances of plusmn70 mum in lateral axis for a working distance of 500mum to PCS optical fibers. The optical coupling power from the transmitter to the PCS fiber has a variation within 1dB over the wide ambient temperature range from -40degC to +105degC. This enables the usage of very low cost plastic molded connector ferrules. The receiver module contains a high speed MSM photodetector. The special design of the MSM photodetector enables high speed operation up to 3.2Gb/s in combination with a large active area for easy alignment. With two pairs of the fiber optic modules, we demonstrate a 1Gb/s video transmission over up to 15m of polymer cladded silica (PCS) optical fiber. The video link consists of a camera with an electrical S800 LVDS interface and a high resolution monitor. A pair of fiber optic cable connects the two ports replacing and extending the regular electrical cable. In contrast to the electrical cable the optical fiber is thin, light weight, and highly flexible. The high power budget margin of the link allows three in-line connectors for the 10-15m link length. For other applications a longer link length is feasible using higher bandwidth optical fiber. The VCSEL based fiber optic transmitter module has passed 3000 hours of high temperature operating life test at an operating ambient temperature of +105degC. The FOTs have also passed 1000 cycles of temperature cycling from -40degC to +125degC according to automotive requirements. The modules have passed electrostatic discharge tests at levels up to plusmn4000V under human body model and plusmn400V for machine model with no significant change in optical output power. The applications include automotive and industrial video links, home networks, and real-time surveillance systems

Low cost transceiver components for short distance optical interconnects

We have investigated plastic-type packages for active optical components in large core optical fiber applications. The chips are mounted on a ceramic submount and connected to a copper leadframe for electrical connection. VCSELs are used on the transmitter side. We have obtained excellent optical and electrical performance over a wide temperature range. Preliminary reliability tests show good results under temperature cycling conditions from -40/spl deg/C to 125/spl deg/C up to 500 cycles. On the receiver side, we have fabricated low capacitance photodiodes that are for large core optical fiber applications. Data rates up to 3.2 Gbps are achieved. The devices are well suited for applications which employ large core fiber such as plastic optical fiber (POF) or polymer cladded silica (PCS) fiber which is also well known as HCS/sup /spl reg// fiber.

Highly integrated plastic package transceiver modules for large core fiber systems

We have developed fiber optic transceivers (FOT) based on leadframe and plastic molding technology for large core POF and PCS fiber systems. The leadframe style package exhibits a compact small size of 9.7mm x 6.2mm x 3.6mm. For PCS fiber system, the VCSEL based fiber optic transceivers have an operating wavelength at 850nm. The transmitter has an internal control circuit to stabilize the optical output of VCSEL and an integrated coupling optics to provide loose alignment tolerances of ±70μm in lateral axis for a working distance of 500μm to PCS optical fibers. The optical coupling power from the transmitter to the PCS fiber has a variation within 1dB over the wide ambient temperature range from -40oC to +105oC. Eye diagrams of the transceivers at 50Mbps are wide open over the normal operating temperature range from -40oC to +105oC. With a pair of VCSEL transmitter and MSM-PD receiver we achieve 1.25Gb/s transmission over 10m of PCS fiber. In a POF transmission system of 40m, over an operating temperature range from -40oC to +85oC, the fiber output power variation with the green LED transmitter is 1.5dB less than that with a similar red LED transmitter. The eye-diagrams of the green LED transmitter at 20Mbps are captured at back-to-back transmission and after 40m POF transmission.

Fiber Optic Transceivers in Surface Mount Technology for High Performance and Low Cost Optical Interconnects

We have developed plastic molded fiber optic transceiver (FOT) modules for surface mounting. The transmitter contains a vertical-cavity surface emitting laser (VCSEL) light source operating at 850nm wavelength, an electronics driver chip, and some passive components. The package is suitable for surface mounting. It shows good stability during reflow soldering in an infrared oven with a peak temperature of 250degC. With a special designed heat shield, the SMT module shows a stable optical alignment before and after the reflow soldering process. The SMT technology enables very low cost component mounting on PCB using automatic pick&place machines. The right material selection and package design is crucial for the stability of the optoelectronic module during the surface mount soldering process. The SMT module is a technology extension of our through-hole mounting FOTs. The output power of the transmitter module is limited to 0.7mW to meet eye-safety class 1 requirements. The transmitter has an internal control circuit to stabilize the optical output of VCSEL and an integrated coupling optics to provide loose alignment tolerances of plusmn70um in lateral axis for a working distance of 500um to polymer cladded silica (PCS) optical fiber with 200um core diameter. The optical coupling power from the transmitter to the PCS fiber has a variation within 1 dB over the wide ambient temperature range from -40deg C to +105degC This enables the usage of very low cost plastic molded connector ferrules. The receiver module contains a high speed MSM photodetector. The special design of the MSM photodetector enables high speed operation up to 5Gb/s in combination with a large active area for easy alignment. With two pairs of the fiber optic transceiver modules, we demonstrate a 1Gb/s video transmission over up to 15m of PCS fiber. The video link consists of a camera with an electrical S800 LVDS interface and a high resolution monitor. A pair of fiber optic cable connects the two ports replacing and extending the regular electrical cable. In contrast to the electrical cable the optical fiber is thin, light weight, and highly flexible. The high power budget margin of the link allows 3 in-line connectors for the 10-15m link length. For other applications a longer link length is feasible using higher bandwidth optical fiber. The SMT fiber optic transceivers enable new low cost applications in automotive, industrial control, and home networking. The technology can compete with electrical solutions on performance and cost and can outperform it on cable flexibility and EMI immunity

Smart Optical Sensors for Industrial and Consumer Applications

ASTRIs smart sensors are based on our low cost plastic packaging platform. We integrate light sources and photodetectors as well as some electronic circuitry elements in a pre-molded plastic package. A precision distance sensor is developed where the diffuse reflection of a VCSEL beam is measured in a position sensitive photodetector element to accurately determine the object position. A micrometer resolution is achieved over several millimeters of working range. The same principle is applied to build a tilt sensor where the tilt of a small size micro chip can be measured with sub-degree accuracy. The application is in the semiconductor assembly industry. The key feature of the smart sensor component is its small size and its light weight, facilitating the mounting on fast moving parts. A different version of the distance sensor enables a touchless optical switch. The optical design with the VCSEL light source and the lens provides a precise switching level. Therefore the optical switch elements can be closely packed without optical crosstalk. The main application is for machines in public environments such as bank teller machines and elevators. The optical switch also enables hermitically sealed switches for outdoor applications

Active components for ultra-low-cost optical interconnects

Low cost optical components enable new emerging applications for short distance interconnects. We developed novel VCSEL transceiver modules based on electronics-style plastic packages for large core PCS fiber systems. The transmission data rate is 500Mbps over a wide ambient temperature range from -40°C to 105°C. For lower data rates we developed green LED based transmitters for extended reach applications using POF. On the receiver side MSM photodetectors exhibit a high sensitivity of -18dBm at a data rate of 3.2Gbps. The large area MSM receivers are essential components for high speed large core optical fiber links.

Highly Reliable and Compact Plastic Fiber Optic Modules for Large Core Optics Fiber Video Link Applications

We have developed high reliable and compact fiber optic modules based on plastic packaging technologies for large core optics fiber video link applications. The outer dimensions of 9.7 mm times 6.2 mm times 3.6 mm are very small compared to standard SFP (small form factor pluggable) modules. The maximum operating temperature of this module is -40degC to +105degC. This is compatible with automotive requirements and much wider compared to typical datacom (85degC) devices. The transmitter module contains a VCSEL, a monitor photodiode, a driver IC chip, and some passive electronics components. This system-in-package technology is quite demanding, because it dealt with devices of different material sets such as Si chips and GaAs chips in one packaging platform. Two pairs of the fiber optic modules are connected with a PCS fiber pair to form an IEEE 1394b S800 compatible video link. The physical data rate is 1 Gb/s due to the built-in 4b/5b coding. The transmission distance is up to 15 m, limited by the bandwidth of the fiber. The extinction ratio is greater than 10 dB. The random jitter is around 100 ps. From the bit error ratio (BER) measurement we obtain a sensitivity of -16 dBm for BER = 1E-09 and a link distance of 5 m. Longer link lengths decrease the sensitivity values due to the modal dispersion of the fiber. However, the system budget is still large enough for all practical application including several in-line connectors. The transceiver modules have been undergone lifetime tests according to automotive application requirements and shown good reliability data. The transmitter module samples have passed 3000 hours of high temperature operating life (HTOL) test at +105degC, 1000 hours of low temperature operating life (LTOL) test at -40degC, 1000 hours of temperature-humidity-biased (THB) test at 85degC/85% R. H, and 1000 cycles of temperature cycling (TC) test from -40degC to +125degC. The receiver module samples have passed 2000 hours of HTOL test at +105degC, 1000 hours of LTOL test at -40degC, 1000 hours of THB test at 85degC/85% R. H, and 1000 cycles of TC test from -40degC to +125degC.

Large core fiber optic transceivers based on plastic molded packages

The article consists of a Powerpoint presentation on large core fiber optic transceivers based on plastic molded packages. The areas discussed include: short distance optical interconnect applications; fiber optic transceivers; output power stabilization; simulated coupling tolerances; eye diagrams; gigabit transmission; FOT reliability and temperature cycling.

High Speed 1Gbit/s Video Transmission with Fiber Optic Technology

We demonstrate a 1 Gbit/s video transmission over up to 15 m of polymer cladded silica (PCS) optical fiber using high speed fiber optic transceiver (FOT) technology. The video link consists of a camera with an electrical S800 LVDS interface and a high resolution monitor. A pair of fiber optic cable connects the two ports replacing and extending the regular electrical cable. In contrast to the electrical cable the optical fiber is thin, light weight, and highly flexible. The high power budget margin of the link allows 3 in-line connectors for the 10–15 m link length. For other applications a longer link length is feasible using higher bandwidth optical fiber.