W. Ebert

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

A waveguide-integrated photodetector is presented, exhibiting a bandwidth of 100 GHz. The responsivity amounts to 0.66 A/W and the PDL is below 0.9 dB. The detector chip is designed to obtain a Bessel filter-shaped transfer characteristic when packaged in a module comprising a 1-mm connector.

Ultrafast, high-power 1.55 /spl mu/m side-illuminated photodetector with integrated spot size converter

40 Gbit/s photodetectors require high bandwidth at high power levels, as supplied by waveguide-integrated p-i-n diodes on InP. By monolithic integration of a spot size transformer a responsivity of 0.5 A/W is achieved and fiber alignment tolerances are increased by one order of magnitude.

MOVPE-based in situ etching of In(GaAs)P/InP using tertiarybutylchloride

Tertiarybutylchloride (TBC) was used as precursor for etching InP and InGaAsP layers in a MOVPE reactor. The effect of different process parameters on the etching rate and morphology was investigated. Similar results were obtained for the carrier gases hydrogen and nitrogen. TBC etching was successfully tested for underetching of mesa stripes, as required in BH-type lasers. Moreover, it proved to be an efficient method for in situ substrate cleaning.

Technology of InP-based 1.55-/spl mu/m ultrafast OEMMICs: 40-Gbit/s broad-band and 38/60-GHz narrow-band photoreceivers

For future long-haul communication systems operating at bitrates of 40 Gbit/s and for broad-band mobile access systems using 38- or 60-GHz carrier frequencies, ultrafast photoreceivers have to be provided. Therefore, an integration concept for InP-based optoelectronic microwave monolithic integrated circuits for the 1.55-/spl mu/m wavelength regime is demonstrated, which allows independent optimization of the constituting devices. Two different types of photodetectors (PDs), a waveguide-integrated PIN photodiode (PD) and a top-illuminated metal-semiconductor-metal PD, both having bandwidths of up to 70 GHz, have been developed. These are fabricated together with different amplifier designs employing high electron mobility transistors which exhibit transit frequencies of up to 90 GHz. The application to a 40-Gbit/s broadband photoreceiver for high-bit-rate time-division multiplexing systems is reported, as well as the application to 38- and 60-GHz narrow-band photoreceivers for use as optic/millimeterwave converters in mobile communication systems.

Ultrafast, high-power waveguide fed photodetector with integrated spot size converter

The monolithic integration of an ultrafast photodetector with an spot size transformer is presented. Using a shifting mask technique optimized taper ramp profiles are fabricated. The integrated devices exhibit a more than doubled responsivity (0.7 A/W) and about one magnitude higher misalignment tolerances compared to devices without spot size converters. The ultra large bandwith (f/sub 3dB/>50 GHz) and the excellent high power behaviour is unimpaired by the integration of the spot size converter.

Growth of InGaAsP/InP-laser structures monitored by using RAS techniques

Reflectance and reflectance anisotropy spectroscopy (RAS) was applied to monitor the MOVPE growth of InGaAsP/InP layers in situ. The basic relationship between the measured optical in situ data and n(Si)- and p(Zn)-doping concentrations of InP, InGaAs and InGaAsP were investigated. Among these materials, InP showed the lowest doping detection limit. Changes in the composition of InGaAsP could be resolved by RAS and reflectance measurements even in the range of a few atomic percent. Combining reflectance and RAS, characteristic fingerprints of all growth steps of a complete 1.3 μm MQW laser structure were generated.

Lasing characteristics of InGaAs/InGaAsP MQW structures grown by low-pressure MOVPE

Abstract InGaAs/InGaAsP MQW SC lasers for 1.55 μm emission wavelength with different numbers of quantum wells have been fabricated using low-pressure MOVPE. Photoluminescence and gain spectra and threshold current densities and the temperature behaviour T 0 of broad area lasers at varying cavity lengths have been investigated.

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

Surface quality of InP etched with tertiarybutylchloride in an MOVPE reactor

In situ etching of InP with tertiarybutylchloride under metalorganic vapor phase epitaxy conditions was investigated with respect to etching profiles, surface morphology, and lateral etching uniformity. Etching of mesa structures resulted in positively sloped sidewalls independent of crystal orientation and etching parameters. Depending on specific etching temperature regimes, excellent surface morphology could be achieved with the addition of PH 3 , or TBP, or even without the presence of any group(V) species. However, strong generation of etch pits was encountered with materials containing high dislocation densities. Preliminary measurements suggest the lateral etched rate uniformity to be very sensitive to the thermal conditions in the reactor owing to the kinetic nature of the etching process.

40 Gbit/s photoreceiver with DC-coupled output and operation without bias-T

The photonic-based telecommunication systems are continuously upgraded to a bit rate of 40 Gbit/s. The demand for faster transmission and the requirement of forward error correction (FEC) in data traffic makes it necessary to further extend the bit rate per channel. One of the key elements to fulfil these demands are high-speed photoreceivers in present and in future optical communication systems. Additional functionalities and cost effective packaging, obtained by a high degree of integration, as well as an increased efficiency and ease of use of the components are mandatory. The InP-based integrated photoreceiver concept with an additional integration of a spot size converter and a redesigned amplifier circuit was developed with these considerations in mind. This new generation of pinTWA Rx-OEICs comprise waveguide-integrated photodiodes with monolithically integrated taper and travelling wave amplifiers with a negative bias-configuration, avoiding an external bias network, and enables the cost effective packaging in a single-chip photoreceiver module with 47 GHz bandwidth.