Paul Brandl

Optical Wireless Communication With Adaptive Focus and MEMS-Based Beam Steering

An optical wireless communication system for an operation with wavelengths detectable by silicon optoelectronic integrated circuits is described. We use direct modulated vertical cavity surface emitting lasers as a transmitter. The field of view of the laser beam is adjusted with an adaptive optical system and aligned with a micro-electro-mechanical system based mirror for beam steering. To receive the modulated laser beam, we develop a receiver chip in 0.35 μm BiCMOS technology. The experimental system shows a 3 Gb/s wireless transmission over a distance of 7 m with a bit-error rate <;10-9 without cost intensive optical components and complex adjustment procedure.

OWC Using a Fully Integrated Optical Receiver With Large-Diameter APD

This letter presents a fully monolithically integrated receiver with a large-diameter avalanche photodiode (APD). Using a standard high-voltage 0.35-μm CMOS technology, the APD is implemented with separated absorption and multiplication regions optimizing the ionization ratio between holes and electrons. This optimized ionization ratio leads to a low excess noise factor of the APD, which considerably improves the receivers sensitivity to -31.8 dBm at 1 Gbit/s (bit error rate <;10-9). A 1-Gbit/s wireless optical communication link with a distance of 3.3 m is demonstrated. Due to the highly sensitive receiver, it is possible to omit any kind of input optics, resulting in a wide receiving angle of 68° for a bit error rate of <;10-9.

PIN Photodiode Optoelectronic Integrated Receiver Used for 3-Gb/s Free-Space Optical Communication

In this paper, an optoelectronic integrated receiver chip including five PIN photodiodes will be presented. A large 200-μm diameter photodiode connected to a high-speed transimpedance amplifier works as a 3-Gb/s receiver for optical wireless communication. Four surrounding photodiodes allow for the adjustment of the incoming laser ray. The complete chip was realized in a silicon 0.35-μm BiCMOS technology to benefit from the available intrinsic zone in this technology. Due to this intrinsic zone and an antireflection coating, the responsivity reaches a value of more than 0.5 A/W for wavelengths from 630 to 760 nm. Furthermore, the capacitance of the center photodiode is less than 0.6 pF for reverse bias voltages larger than 3 V. For proof of concept, a steerable and adjustable light source was built based on a micro-electro-mechanical system mirror, on a focusing unit, and on a direct modulated vertical cavity surface emitting laser with a wavelength of 680 nm. The complete system is capable of establishing a 3-Gb/s data transfer over a distance of 19 m at a BER of <;10-9, and over a distance of 18 m at a BER of <;10-12.

Automated alignment system for optical wireless communication systems using image recognition

In this Letter, we describe the realization of a tracked line-of-sight optical wireless communication system for indoor data distribution. We built a laser-based transmitter with adaptive focus and ray steering by a microelectromechanical systems mirror. To execute the alignment procedure, we used a CMOS image sensor at the transmitter side and developed an algorithm for image recognition to localize the receivers position. The receiver is based on a self-developed optoelectronic integrated chip with low requirements on the receiver optics to make the system economically attractive. With this system, we were able to set up the communication link automatically without any back channel and to perform error-free (bit error rate <10⁻⁹) data transmission over a distance of 3.5 m with a data rate of 3 Gbit/s.

Optical Wireless APD Receiver With High Background-Light Immunity for Increased Communication Distances

The design and measurement of a monolithically integrated optoelectronic chip consisting of two different receivers are presented. A high-speed receiver for communication including a highly sensitive, large-area avalanche photodiode builds one receiver. A data rate of 1 Gbit/s with a BER <;10-9 is received with a sensitivity of -31.8 dBm. The second receiver consists of two pn-photodiodes connected to a highly sensitive differential transimpedance amplifier with a nonlinear feedback. This circuit is capable of detecting light power differences down to -90 dBm and is implemented two times. Its purpose is the detection of the light spots position on the receiver. The complete chip is fabricated in a standard high-voltage 0.35 μm CMOS technology. The performance in a wireless communication scenario with strong background irradiance is explored, and a comparison with published optoelectronic integrated receivers is given.

OWC using a monolithically integrated 200 µm APD OEIC in 0.35 µm BiCMOS technology

A lens-less receiver with a monolithically integrated avalanche photodiode (APD) in 0.35 µm BiCMOS technology has been developed for establishing an indoor 2 Gb/s optical wireless communication (OWC) over a distance of 6.5 m with a receiving angle of 22°. Immunity toward background light was demonstrated up to 6000 lux. Four additional PIN photodiodes with highly sensitive differential nonlinear transimpedance amplifiers (TIA) were implemented on the receiver chip for centering the highly collimated transmitter beam position.

10 Gb/s Switchable Binary/PAM-4 Receiver and Ring Modulator Driver for 3-D Optoelectronic Integration

This paper presents ring modulator driver and receiver circuits designed for three-dimensional photonic-electronic integration using interwafer connections, whose parasitic capacitance is expected to be in the order of 15 fF. Both transmitter and receiver can operate with binary and PAM-4 modulation at 10 Gb/s. To the authors knowledge, it is the first PAM-4 ring modulator driver being presented. The circuits are designed in AMS 0.35-μm SiGe BiCMOS technology with total power consumptions of 160 and 180 mW for transmitter and receiver, respectively. The receivers sensitivity is -27 dBm for binary and -22 dBm for 4-PAM signals both at a photodiode responsivity of R = 0.9 A/W. A monitor transimpedance amplifier with sensitivity -32 dBm was also designed in order to control the operating point of the ring modulator.

Optical wireless receiver circuit with integrated APD and high background-light immunity

This paper presents two different monolithically integrated optoelectronic receiver circuits in one chip. One circuit includes a 200 μm diameter, high responsivity avalanche photodiode with a highly-sensitive receiver for wireless optical data communication at a data rate of 1Gbps with a sensitivity of -31.8 dBm. The second circuit includes two PN-photodiodes and a differential TIA with a nonlinear feedback to detect light power differences down to -90 dBm. The second circuit is implemented twice: for beam positioning in x- and y-direction. The chip was fabricated in a 0.35 μm high-voltage CMOS technology and tested under strong background-light conditions representative for optical wireless communication scenarios.

Development of an optoelectronic integrated circuit for indoor optical wireless communication systems

Indoor optical wireless communication systems use in most cases discrete built receivers. The analogue part of receivers consists of a photodetector and an amplifier. In this paper, we present a fully integrated optoelectronic integrated circuit that combines a photodetector and an amplifier into one single receiver chip. We show the evolution of such receivers and examine the benefits of their production as standard semiconductor chip. We developed a fully integrated receiver for a 3Gbit/s communication in standard BiCMOS technology. We expanded the receiver by additional photodetectors to have the possibility of implementing an automatic alignment system. To demonstrate the performance of this receiver, we built a complete indoor optical wireless communication system. We increased the working area of the system by applying two strategies at the transmitter side. First, we used an adaptive optical system to influence the laser spot diameter. Second, to steer the laser beam, we included a micro-electro-mechanical system. Copyright

1.25Gbit/s integrated receiver for optical wireless communication systems

For optical wireless communication systems a receiver with a monolithically integrated PIN photodiode has been developed. The circuit was produced using 0.5 μm BiCMOS technology and with an indoor measurement setup we reached a data transfer rate of 1.25 Gbit/s with a bit error rate of 5.24 × 10-11. The link distance between transmitter and receiver was 3.2 m and the photodiode of the integrated receiver had a diameter of 300 μm.