In this paper, we demonstrate for the first time the far-field experimental results and the linewidth characteris-
tics for widely tunable surface-micromachined micro-electro-mechanical system (MEMS) vertical-cavity surface-
emitting lasers (VCSELs) operating at 1550 nm. The fundamental Gaussian mode emission is confirmed by
optimizing the radius of curvature of top distributed Bragg reflector (DBR) membrane and by choosing an ap-
propriate diameter of circular buried tunnel junctions (BTJs) so that only the fundamental Gaussian mode can
sustain. For these VCSELs, a mode-hop free continuous tuning over 100 nm has already been demonstrated,
which is achieved by electro-thermal tuning of the MEMS mirror. The fiber-coupled optical power of 2mW over
the entire tuning range has been reported. The singlemode laser emission has more than 40 dB of side-mode
suppression ratio (SMSR). The smallest linewidth achieved with these of MEMS tunable VCSELs is 98MHz
which is one order of magnitude higher than that of fixed-wavelength VCSELs.
We present surface micro-machined micro-electro mechanical-system (MEMS) tunable vertical-cavity surfaceemitting
lasers (VCSEL) with rectangular and triangular shaped quantum wells (QWs) emitting around 1:95 μm
predestined for broadband tunable diode laser absorption spectroscopy. The VCSELs show single-mode operation
and high side-mode suppression-ratio SMSR < 50 dB within the whole tuning range of 50nm and 35 nm, the
fibre-coupled optical power of 1:0mW and 1:76mW and the threshold current of 2:5mA and 2:0mA for the
rectangular and triangular shaped QWs respectively. The 3 dB modulation frequency of the MEMS is 110 Hz.
A mode hop free single mode tuning < 90nm at 40°C and 45nm at 70°C is demonstrated with a MEMS tunable VCSEL for the first time. The device shows a fiber-coupled output power of 2.9mW at 20°C and 0.5mW at 70°C. The side mode suppression ratio is larger than 40 dB over the entire tuning and temperature range of up to 70°C. The presented technology is cost effective and thus capable for mass production. It is applicable for tuneable VCSELs operating in different wavelength regimes, which are limited by the absorption of the DBR materials only.
We investigate experimentally resonant-tunnelling-diode (RTD) oscillators, which are based on RTDs with heavily
doped collector. We demonstrate that such RTD oscillators can work at frequencies, which are far beyond the
limitations imposed by resonant-state lifetime and relaxation time. Exploiting further such RTDs, we have
achieved the record operating frequency of 1.1 THz and show that substantially higher frequencies should be
also achievable with RTD oscillators. RTD oscillators are extremely compact (less than a square millimeter)
room-temperature sources of coherent cw THz radiation. Such sources should enable plenty of real-world THz
applications.
We present a micro electro-mechanical system (MEMS) tunable vertical-cavity surface-emitting laser (VCSEL) emitting
around 1.55 μm with single-mode output power of >2.5mW and high side-mode suppression-ratio (SMSR) of >50dB
over the entire tuning range of >50nm. The small-signal modulation technique (S21) has been used to study intrinsic and
parasitic influences on the modulation response of the device. Additionally, the static characteristics as well as electrical
and thermal design of the device are discussed with respect to its high-speed modulation behavior. The tunable laser
shows 3-dB direct modulation frequencies above 6.4 GHz.
We report the investigation of the state of polarization (SOP) of a tunable vertical-cavity surface-emitting laser
(VCSEL) operating near 850 nm with a mode-hop free single-mode tuning range of about 12 nm and an amplitude
modulation bandwidth of about 5 GHz. In addition, the effect of a sub-wavelength grating on the device and
its influence on the polarization stability and polarization switching has been investigated. The VCSEL with an
integrated sub-wavelength grating shows a stable SOP with a polarization mode suppression ratio (PMSR) more
than 35 dB during the tuning.
We present surface micro-machined tunable vertical-cavity surface-emitting lasers (VCSELs) operating around
1550nm with tuning ranges up to 100nm and side mode suppression ratios beyond 40 dB. The output power
reaches 3.5mW at 1555 nm. The electro-thermal and the electro-statical actuation of a micro electro-mechanical
system (MEMS) movable distributed Bragg reflector (DBR) membrane increases/decreases the cavity length
which shifts the resonant wavelength of the cavity to higher/lower values. The wavelength is modulated with
200 Hz/120 kHz. Both tuning mechanisms can be used simultaneously within the same device. The newly
developed surface micro-machining technology uses competitive dielectric materials for the MEMS, deposited
with low temperature plasma enhanced chemical vapor deposition (PECVD), which is cost effective and capable
for on wafer mass production.
Polarization mode dispersion is the limiting factor in todays large capacity photonic network systems since it
causes intersymbol interference especially at high data rates. When polarization multiplex is employed to increase
spectral efficiency, the distortions caused by polarization mode dispersion get even stronger due to the
additional polarization crosstalk. Employing coherent detection these mitigations can be fully compensated with
linear filters, since coherent detection delivers amplitude, phase and polarization information of the electrical
field. As a drawback we have to take into account a high complexity of the receiver, causing high overall cost.
At the other hand we have direct detection systems where the receiver complexity can be kept low. Furthermore
maximum likelihood sequence estimation detection has been successfully demonstrated for standard direct detection
systems. In a first step an advanced maximum likelihood sequence estimation detector, which is able to
work in an intensity modulated polarization multiplex direct detection system, is developed. The performance of
the detector is assessed by simulations and it is shown that it is capable to significantly reduce system outages.
The method then is compared with a least mean squares based equalizer which is employed to compensate for
signal distortions in an intensity modulated polarization multiplex coherent detection transmission system.
Widely tunable vertical cavity surface emitting lasers (VCSEL) are of high interest for optical communications,
gas spectroscopy and fiber-Bragg-grating measurements. In this paper we present tunable VCSEL operating at
wavelength around 850 nm and 1550 nm with tuning ranges up to 20 nm and 76 nm respectively. The first versions
of VCSEL operating at 1550 nm with 76 nm tuning range and an output power of 1.3mW were not designed for
high speed modulation, but for applications where only stable continious tuning is essential (e.g. gas sensing).
The next step was the design of non tunable VCSEL showing high speed modulation frequencies of 10 GHz with
side mode supression ratios beyond 50 dB. The latest version of these devices show record output powers of
6.7mW at 20 °C and 3mW at 80 °C. The emphasis of our present and future work lies on the combination of
both technologies. The tunable VCSEL operating in the 850 nm-region reaches a modulation
bandwidth of 5.5GHz with an output power of 0.8mW.
We present 1.55 μm short-cavity buried-tunnel-junction VCSELs (Vertical-Cavity Surface-Emitting Lasers) with single
mode output powers of 6.7 mW at 20°C and 3 mW at 80°C, respectively. Although the device had been predominantly
optimized for high-power applications and a proper heat management, we are also observing a 3dB-cut-off frequency of
more than 11 GHz and side mode suppression ratios (SMSRs) beyond 54 dB over the whole temperature range. The
tuning range of the devices can be increased from 7 nm based on gain tuning to several tens of nanometers when
replacing the top DBR by a micro-electro-mechanical system (MEMS) distributed Bragg reflector (DBR) composed of
semiconductor or dielectric material being thermally actuated for changing the cavity length. These devices are perfectly
suitable for telecommunication and gas sensing applications and represent outstanding devices for the so called tunable
diode laser absorption spectroscopy (TDLAS) technique.
The still increasing demand for data bandwidth in short-haul transmission as well as in long- haul transmission
implicates the development of optical high-speed communication systems that carry 40 Gbit/s and higher. This
step is limited mainly by the polarization mode dispersion (PMD) of the fiber infrastructure. Direct detection
transmission systems are state of the art. At this the square-law detection of the photo diode transforms linear
distortions into nonlinear effects, which makes linear equalization principles less effective. Coherent detection on
the other hand delivers amplitude, phase and polarization information of the field and thus enables advanced
PMD-compensation in the electrical domain. We realize PMD-compensation by means of least mean squares
based adaptive electronic equalizers. The drawback of adaptive equalization principles is the setting of the
adaption step-size. Small step-sizes lead to very accurate results, but are very time-consuming. By contrast
large step-sizes can accelerate the adaption process but lead to inaccurate equalizer settings. Accordingly, it
is desirable to resize the step-size during the adaption process. For these reasons different step-size control
algorithms are implemented, analyzed and adapted to the requirements of an optical PMD affected transmission
system. It shows that step-size control algorithms are able to accelerate the adaption-process significantly.
The design, technology and characteristics as well as sensing applications of micromachined long-wavelength
(~1.55μm) tunable vertical-cavity surface-emitting lasers are reported. The laser combines an active optical
component (so-called half-VCSEL) and an agile mechanical component (MEMS) in a hybrid assembly. Electrothermal
actuation expands the enclosed air-gap and continuously shifts the cavity resonance towards longer
wavelengths. A curved mirror membrane is deployed to solely excite the desired fundamental mode with high
output power and high sidemode suppression. The comparatively high stiffness of the MEMS lifts its mechanical
resonance frequency to values around 150 kHz as measured by laser Doppler vibrometry under electrostatic
actuation and - at the same time - reduces its susceptibility to Brownian motion. Laser linewidths as narrow
as 32MHz are demonstrated by using the self-heterodyning technique and the wavelength dependent linewidth
variation is presented for the first time. After successful absorption spectroscopy experiments under steady
laboratory conditions the tunable VCSEL is used for trace gas detection in a combustion process. Preliminary
experimental results are shown and practically encountered problems are discussed.
We present the characterization of silicon oxide (SiOx) and silicon nitride (SiNx) films deposited by inductively
coupled plasma chemical vapour deposition (ICP-CVD) at low temperature (< 100°C). A tunable optical Fabry-
Perot (FP) -filter operating at a wavelength around 1.5μm is realized. It is hybridly assembled with two dielectric
distributed Bragg reflectors (DBR). One of the DBR- mirrors is intentionally curved using the intrinsic stress
inside the films. Our aim is the development of a tunable surface micromachined VCSEL with a curved dielectric
mirror. Therefore ICP-CVD with a low deposition temperature is used for SiOx and SiNx films. As a first step
the realization of a tunable bulk- mircomachined optical FP- filter is presented. The refractive index, deposition
rate, stress and etching rate in buffered hydrofluoric acid (BHF) of thin dielectric films (<500 nm) in dependence
on deposition temperature and on gas flow ratio are investigated. The knowledge of the deposition characteristics of the dielectric films is used to realize DBRs with a given curvature that are applied to electrothermally actuated, optical tunable FP- filters. The presented filter has a free spectral range of 29 nm, an insertion loss of 10 dB and a full width half maximum of 0.16 nm.
We utilize the reflectivity of one-dimensional metal gratings with sub-wavelength slits to realize mirrors for THz
frequencies. Two of them are combined to a Fabry-Perot filter, which features the corresponding transmission
bands. By appropriate choice of dimensions, the extraordinary transmission resonance of the sub-wavelength
gratings can be superimposed with the Fabry-Perot peak. By varying the resonator length between the grating
mirrors, the overlap of both transmission peaks can be controlled. This enables the tuning of the filter bandwidth.
The theoretical analysis shows that continuous tuning of the filter bandwidth up to 30% is possible for a two
mirror stage. For the performance of comparative measurements, an all-fiber continuous-wave THz system is
used. The experimental results are in fairly well agreement with the theoretically predicted tuning properties.
Due to the growing demand of bandwidth in optical communication systems, the step towards 40 Gbit/s is inevitable. This step is limited mainly by the polarization mode dispersion of the fiber infrastructure. To extend the usability of the infrastructure it is necessary to employ PMD-compensation. The On/Off-keying modulation format in conjunction with direct detection is state of the art in high bitrate optical communication systems. But as a drawback, direct detection only provides an output signal which is proportional to the square of the absolute value of the electrical field and therefore transforms linear effects such as PMD into the nonlinear domain, which makes linear compensation schemes less effective. Coherent detection on the other hand delivers amplitude, phase and polarization information of the field and thus enables advanced PMD-compensation in the electrical domain. In our work, we employ optical coherent detection to receive two orthogonal components of the complex valued electrical field of an On/Off-keying modulated optical carrier. This single input multiple output system delivers us up to four output signals, i.e. real and imaginary part of the two detected polarization planes, which can be fed to feed forward equalizers or other electronic processing methods for an effective compensation of signal distortions caused by PMD. The required feed forward equalizer settings and their performance are presented.
As is well known, chromatic dispersion (CD) and nonlinear effect such as self-phase modulation (SPM),
cross-phase-modulation (XPM), and four-wave-mixing (FWM), as well as their impairments interaction
with each other are recognized as a limiting impairment for a high bit rates optical systems. With the advent
of the 40 Gb/s, it is necessary to study transmission performance, which clearly depends on the modulation
format and the system design.
A numerical comparison of non-return-to-zero (NRZ), return-to-zero (RZ) and differential phase shift
keying (DPSK) formats is made at a bit rate of 40 Gbit/s for single-channel and WDM systems with
different compensation method in attempt to find the optimum modulation format. The transmitter under
consideration used a 1.5 um DFB-laser externally modulated by a MZM modulator with modulation format
(NRZ, RZ, DPSK), 64 PRBS data. At the receiver end an optical filtering using gaussian, fabry-perot and
rectangular filter is used. Between the compensation method the symmetrical design leaves the best results
in comparison to pre- and post-compensation. The impact of SPM can be reduced considerably by the
symmetrical design. NRZ shows a best toleranz again chromatic dispersion and DPSK a best toleranz to
Nonlinearity.
Polarization mode dispersion (PMD) is one of the major limitations for optical transmission systems at 10 Gb/s and beyond. While first- or second-order PMD compensators (PMDC) can be driven with a feedback signal, more complex broadband PMDCs have to be set feed forward. An exact knowledge of the fiber's PMD characteristics - e.g. the PMD vector - is needed for the feed forward setting. Since PMD changes with time, real-time PMD measurement without data traffic interruption is necessary. Some recently published frequency- and time-domain methods meet these conditions. In this publication we are going to examine and compare different on-line measurement methods. Using numerical simulations, the performance of the measurement methods is assessed in terms of the accuracy of the PMD vector measurement and the qualification as feed forward control signal for setting a PMDC. The measurements exhibit an inherent inaccuracy if the signal is launched close to one of the principal states of polarization (PSP). Although these combinations of PSP and signal polarization result in inaccurate PMD vector measurements, the transmitted signal is not degraded by first order PMD. Consequently, the accuracy of the PMD vector measurement is a bad figure of merit for the performance of a system including a feed-forward set PMDC. Furthermore, due to the averaging over the signal bandwidth, the measured PMD vector is a better control variable for a PMDC than the analytically calculated PMD vector if second order PMD is considered.
The most common model used for PMD simulations visualizes the fiber as a concatenation of a large number of birefringent elements. This system's DGD has the same Maxwellian PDF for each frequency. By measurement of certain links it is shown that the PDF of the DGD is not equal for all of the frequency bands. This behavior could be traced back to the fact that fiber links consist of a certain number of stable buried sections, with nearly no PMD changes over weeks and months. These sections are connected by sections exposed to strong temperature variations, acting as polarization rotators. This new model of a fiber link is known as the hinge model. To characterize these hinges, the temperature dependent behavior of several DCM and patch cords commonly used in WDM systems have been investigated. Measurements showed that DCM are the most active hinges. They produce approximately a full rotation in Stokes space when heated 1°C. This rotation is both reproducible and reversible. An novel model of the analyzed DCM has been developed in Matlab, which is able to reproduce the described measured behavior in simulations. The frequency dependency of the DGD's PDF leads from overall systems outage probability to frequency selective outage probability. That means instead of having a system outage at a certain outage probability, outage probabilities are connected to a number of outage channels.
Tailored scaling allows the effectiveness of physical effects and mechanical stability to be enhanced. This is shown for micromachined 1.55μm vertical-resonator-based filters and VCSELs, capable of wide, continuous, and kink-free tuning by a single control parameter. Tuning is achieved by mechanically actuating one or several membranes in a vertical air-gap resonator including two highly reflective DBR mirrors. Electrostatically actuatable single-chip filters including InP/air-gap DBR's (3.5 periods) reveal a continuous tuning up to 14% of the absolute wavelength. Varying a reverse voltage (U=0 .. -3.2V) between the membranes (almost flat in the unactuated condition) a tuning range up to 142nm was obtained. Varying a reverse voltage (U=0 .. -28V) between the membranes (strained and curved in the unactuated condition) a tuning range up to 221nm was obtained. Optically pumped and continuously tunable 1.55μm VCSELs show 26nm spectral tuning range, 400μW maximum output power, and 57dBm SMSR. This two-chip VCSEL has a movable top mirror membrane, which is precisely designed to obtain a specific air-gap length and a tailored radius of curvature in order to efficiently support the fundamental optical mode of the plane-concave resonator. The curved top mirror DBR membrane consists of periodically alternating differently stressed silicon nitride and silicon dioxide multilayers. The lower InP-based part consists of the InP/GaInAsP bottom DBR and the GaInAsP active region.
This paper presents different approaches to enable high-speed
transmission of 10 Gbit/s and beyond on polarization mode
dispersion (PMD) limited fibers. An introduction to the phenomenon
of PMD and its impact on system performance is presented. An
overview of common optical PMD mitigation methods and their basic
concept is given, including the problem of multi-channel PMD
compensation schemes for WDM systems. Furthermore alternative
methods like polarization scrambling, forward error correction and
electrical mitigation are considered. Bit error rate (BER)
determined by error counting is used as quantification for PMD
induced outages and a comparison to eye opening penalty (EOP)
based performance evaluation is given. The performance of basic
PMD mitigation schemes is compared by using the EOP and the BER
based outage criterion.
In this paper, a novel two-chip-concept for an electrically pumped and micro-mechanically tunable vertical-cavity surface-emitting laser (VCSEL) operating in the 1.55 μm wavelength range is presented. One chip contains the active region with 5 quantum wells based on the material system AlGaInAs/InP and a buried tunnel junction (BTJ) to provide current confinement and waveguiding. A dielectric mirror forms the back reflector. The second chip consists of a curved mirror membrane that can be displaced by electro-thermal heating. The main advantage of this approach is that both parts can be optimized separately. Packaged laser devices show continuous-wave operation at room temperature with an output power of up to 200 μW and very good side mode suppression in the order of 45 dB. Single-mode operation was observed across a tuning range of more than 30 nm.
Wavelength Division Multiplexing has become the leading technology for optical transmission systems which operate at 1550 nm. One of the key components of such systems are tunable and wavelength selective receivers. In this paper we present a fibre-coupled two-chip receiver front end, which is highly wavelength selective and tunable over a wide wavelength range. The device is a bulk-micromachined Fabry-Perot pin-photodiode, which features a high finesse of more than 220 with a sufficient tuning range (> 40 nm) to cover wide wavelength region. The bandwidth (full-width half maximum) of the device is < 0.2 nm (25 GHz). The photocurrent crosstalk from an adjacent channel (100 GHz spaced apart) is below -30 dB. The wavelength tuning is achieved by a change in the resonator length, formed by the two chips. This is realized by current induced thermal heating on top of the membrane mirror suspensions, which deflects the membrane. The optical-electrical conversion takes place in the pin-photodiode. This integration reduces the need for any additional components. Fiber-coupling is achieved with a fiber-coupled lens that tailors the Gaussian beam to match with the Fabry-Perot cavity. The alignment process of the two-chip structure, forming the wavelength selective cavity, has been simplified to the point where a simple place-and-fix strategy can be applied.
Tunable vertical cavity surface emitting lasers (VCSELs) are very attractive candidates for employment in various areas of interest, like optical communications or gas sensing. During the last decade these types of components have been demonstrated. In this paper we present a micromechanically realization of an optically pumped 1.55 μm tunable VCSEL and its characteristics. The investigated device comprises two chips. The first chip, a half-cavity VCSEL chip, contains the bottom Bragg-mirror and the active layers. The second chip is a micromechanically manufactured Bragg-mirror membrane chip. After aligning, both chips form together the VCSEL cavity. Wavelength tuning is achieved by thermal actuation of the membrane mirror due to current flow and the subsequent deflection of the mirror membrane resulting in a change of the resonance wavelength. Such a micromachined two-chip VCSEL device is investigated and discussed. In particular, properties like the side mode suppression ratio, relative intensity noise and polarization during actuation and their dependence on the properties of the micromachined mirror-membrane are analyzed. Remarkable results are e.g. the side mode suppression ratio dependence on the pump spot size, the dependence of the relative intensity noise of the VCSEL on the pump laser noise, and stable polarization due to the membrane design.
Chromatic dispersion and polarization mode dispersion (PMD) are the most relevant disturbances in optical high speed transmission systems. The influence of chromatic dispersion can be overcome by different methods such as dispersion compensating fibers or fiber gratings. Because of its stochastic behavior the struggle against
PMD is much more troublesome and essential for bit rates above 10 Gbit/s. The paper describes the influence of polarization mode dispersion derived from basic principles of transmission. It gives some physical understanding and simple derivation of the characteristic equations of PMD. One distinguishes between first and second order PMD. An optical fiber link showing first order PMD only can be modelled by a waveguide with time varying birefringence. If the birefringence additionally is frequency dependent the fiber will show higher order polarization mode dispersion. PMD compensators can be divided in a similar manner: compensators considering first order PMD only and compensators including PMD of higher order. Compensators operating in the optical domain or in the electrical
domain have been proposed.
Wavelength Division Multiplexing has become a leading technology for long haul transmission systems which operate at 1550 nm wavelength. One of the key components of such systems are tunable filters. Beside low insertion loss, polarisation insensitivity and large tuning range there is a strong demand for cost effectiveness and reliability. Two-chip micromachined filters are very promising candidates to fulfil these demands. In this paper we present and discuss a tunable optical filter structure which uses a simple bulk-micromachining process based on low-cost dielectric Bragg mirrors. The tuning is achieved by current induced thermal heating of the membrane suspensions. Common micromachined tunable optical filters either employ semiconductor Bragg mirrors with current induced heating or dielectric membrane mirrors with electrostatic actuation. The new concept combines the advantages of both types, the low-cost dielectric material and the simple actuation principle by current flow to create a best-of-breed two-chip solution. The alignment process of the two-chip cavity has been simplified to the point where a simple place-and-fix strategy can be applied. By matching the exciting Gaussian input beam to the stable half-symmetric cavity a fiber coupled and packaged tunable optical filter has been realized based on this concept. These micromachined tunable membranes are in general applicable to a wide variety of tunable components for wavelength division multiplexing systems, such as tunable optical filters, receivers and vertical cavity surface emitting lasers (VCSEL).
Wavelength Division Multiplexing has become a leading technology for long haul transmission systems which operate at 1550 nm wavelength. One of the key components of such systems are tunable filters. Beside low insertion loss, polarization insensitivity and large tuning range there is a strong demand for cost effectiveness and reliability. Two-chip micromachined filters are very promising candidates to fulfill these demands. Two Bragg mirrors are deposited on distinct chips. One of them is engineered as actuable membrane. The Fabry- Perot cavity is created by proper adjustment of the two chips one against the other. Modifying the cavity length by thermal induced heating of the membrane mirror or by applying an electrostatic force provides tunability of the transmission function. Tuning stability and insertion loss can be considerably improved if a stable half symmetric cavity containing a bend membrane instead of a flat one is used. This also helps to overcome some severe fabrication problems. On the other hand the half symmetric cavity is more sensitive to mismatch between filter geometry and phase fronts of the existing Gaussian beam. This aspect and the tolerances which can be accepted are discussed in this paper in detail.
A micromechanically wavelength-tunable optical filter with an integrated pin-photodetector for the wavelength band around 1.55 micrometer is demonstrated. The micromechanical modification of the resonator length realized by either thermal or electrostatic actuation of micromachined Bragg reflectors is used as tuning principle. The maximum tuning of the filter can be determined by its free spectral range (FSR) in the order of 40 nm, according to a resonator length around 30 micrometer. The required micromechanical displacement of the movable Bragg mirror of 800 nm is observed for an actuation voltage of 32 V utilizing capacitive actuators, while a heating power of 1.3 mW is required for electrothermally actuated membranes. Epitaxial (InAlGaAs/InAlAs) as well as dielectric (SiO2/Si3N4) material compositions are used for the Bragg reflectors to meet the mechanical and optical demands of the filter. The experimental full width at half maximum (FWHM) of the tunable wavelength division multiplexing (WDM) filter is 0.24 nm corresponding to a finesse of F equals 180. The insertion loss at resonance wavelength is 2.8 dB, whereas the contrast between maximum and minimum transmission exceeds 40 dB. The integration of an InGaAs/InP photodiode and a bulk- micromachined Bragg mirror allows the realization of a wavelength-selective pin photodetector. We report on bulk- micromachined thermally actuated highly selective photodetectors with a maximum tuning range of 35 nm, a FWHM around 0.4 nm and a tuning sensitivity of 20 nm mW-1. The technology discussed in this paper will be compatible to opto-electronic integrated circuit (OEIC) fabrication processing based on the InP-material system and therefore will enable the realization of receiver front ends with higher functionality for future dynamic WDM systems.
We have fabricated InGaAs/InP PIN diodes with a coplanar waveguide design. The diodes have been integrated in a two- chip wavelength-selective Fabry-Perot filter for the use as wavelength-selective PIN receivers for dense wavelength division multiplex systems.
Rolf Riemenschneider, Joachim Peerlings, Joachim Pfeiffer, A. Dehe, Andreas Vogt, Peter Meissner, Hans Hartnagel, N. Chitica, Juergen Daleiden-, Klaus Streubel, Harald Kuenzel, W. Goertz
Monolithically-integrated wavelength-selective receivers are needed for dense wavelength-division multiplex transmission in the 1.55 micrometers wavelength regime. We present a novel concept for tunable optical Fabry-Perot filters with long resonant cavities of about 30 micrometers . III-V semiconductor technology compatible to PIN detector integration is applied to fabricate bulk-micromachined movable membrane Bragg mirrors. The initial membrane curvature as well as the actuation-induced bending are analyzed using a white light interferometer. Continuous filter tuning achieved by thermal or electrostatical actuation is analyzed in the optical as well as in the mechanical regime. Opto-mechanical constraints of the realized filters are discussed in view of novel epitaxial demands and optimum design for micro-opto- electro-mechanical receiver systems.
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