Photonic integrated circuits (PICs) are considered as the way to make photonic systems or subsystems cheap and ubiquitous. PICs still are several orders of magnitude more expensive than their microelectronic counterparts, which has restricted their application to a few niche markets. Recently, a novel approach in photonic integration is emerging which will reduce the R&D and prototyping costs and the throughput time of PICs by more than an order of magnitude. It will bring the application of PICs that integrate complex and advanced photonic functionality on a single chip within reach for a large number of small and larger companies and initiate a breakthrough in the application of Photonic ICs. The paper explains the concept of generic photonic integration technology using the technology developed by the COBRA research institute of TU Eindhoven as an example, and it describes the current status and prospects of generic InP-based integration technology.

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An introduction to InP-based generic integration technology

This paper provides an overview on recent advances of InP-based photodetectors for high-speed fiber-optic applications, with emphasis on evanescently coupled waveguide photodiodes, balanced receivers, and distributed traveling wave photodetectors.

InP-Based High-Speed Photodetectors

To date, exploiting the full bandwidth of state-of-the-art InGaAs photomixers for generation and detection of continuous-wave (CW) THz radiation (typ. ~50 GHz to ~3 THz) required complex and costly external-cavity diode lasers with motorized resonator control. Distributed feedback (DFB) lasers, by contrast, are compact and inexpensive, but the tuning range per diode is limited to ~600 GHz at 1.5 μm. In this paper, we show that a combination of three DFB diodes covers the complete frequency range from 0 – 2750 GHz without any gaps. In combination with InGaAs-based photomixers for terahertz generation and detection, the system achieves a dynamic range of > 100 dB at 56 GHz, 64 dB at 1000 GHz, and 26 dB at 2500 GHz. A field-programmable gate array (FPGA)-based lock-in amplifier permits a flexible adjustment of the integration time from 0.5 ms to 600 ms. Employing an optimized “fast scan” mode, a spectrum of ~1200 GHz – the bandwidth of each subset of two lasers – and 40 MHz steps is acquired in less than one minute, still maintaining a reasonable dynamic range. To the best of our knowledge, the bandwidth of 2.75 THz presents a new record for DFB-based CW-terahertz systems.

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2.75 THz tuning with a triple-DFB laser system at 1550 nm and InGaAs photomixers

A compact and low-cost continuous wave terahertz spectrometer operating at an optical wavelength of 1.5 μm is presented. The spectrometer employs high power distributed feedback (DFB) laser diodes in integrated “butterfly” packages. No further optical amplification of the beating signal is required. An integrated photodiode antenna with an output power of 5 μW at 500 GHz is used as efficient terahertz emitter. Employing low-temperature grown (LT-) InGaAs/InAlAs photoconductive receivers as coherent detectors, SNR values of the terahertz power up to 75 dB are attained at an integration time of 300 ms. Accurate characterization of the thermal tuning behavior of the DFBs and precise thermal control yield an absolute accuracy of 1 GHz and a resolution of better than 5 MHz, without any on-line monitoring of the optical frequency. Due to the high frequency resolution no delay line is needed to vary the terahertz phase.

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Compact cw Terahertz Spectrometer Pumped at 1.5 μm Wavelength

A fiber-assembled CW THz System operating at 15 microm is presented High speed telecom photodiodes integrated with planar THz antennas serve as THz emitters with power up to 10 microW Photoconductive antennas based on LT InGaAs/InAlAs multi-layer structures allow coherent detection The system operates in a wide frequency range of 01 -16 THz

Continuous wave terahertz systems exploiting 1.5 microm telecom technologies.

A waveguide-integrated photodetector is presented, exhibiting a bandwidth of 100 GHz The responsivity amounts to 066 A/W and the PDL is below 09 dB The detector chip is designed to obtain a Bessel filter-shaped transfer characteristic when packaged in a module comprising a 1-mm connector

InP-based waveguide-integrated photodetector with 100-GHz bandwidth

A novel balanced photoreceiver with integrated amplifier, based on InP, is presented. The device exhibits an overall conversion gain of 35 V/W, low output reflection and well opened synthesized eye pattern at 40 Gbit/s NRZ modulation format.

Monolithically integrated balanced photoreceiver OEIC comprising a distributed amplifier for 40 Gbit/s applications

The fabrication and characterization of InP-based narrowband photodetector OEICs and modules, covering the frequency range 38-90 GHz, is reported. The reverse bias tuneable detectors exhibit 0.55 A/W peak responsivities at 80 GHz, equal to the DC value.

http://ieeexplore.ieee.org/iel5/9837/30998/01442773.pdf

W. Schlaak

Papers

InP-based waveguide-integrated photodetector with 100-GHz bandwidth

Monolithically integrated balanced photoreceiver OEIC comprising a distributed amplifier for 40 Gbit/s applications

Highly efficient InP-based narrowband photodetectors for 40 to 85 GHz linear high power applications