Oct 01, 2002 a optical transmitter for digitally modulated radio frequency subcarriers comprising. Characterization of an electroabsorption modulator design. The output is a result of interference, ranging from. The relations between transfer functions and other system descriptions of dynamics is also discussed. Jp3880868b2 electroabsorption modulated laser with high. Modeling of machzehnder and electroabsorption modulator. Modulation transfer function mtf the contrast in an image can be characterized by the modulation m smax. Index termselectroabsorption modulator, optical loss, photo current, saturation. The interferometer has been used, among other things, to measure phase shifts between the two beams caused by a sample.
Onorbit modulation transfer function mtf measurements for ikonos and quickbird civil commercial imagery evaluation workshop 3152006 dennis helder, jason choi, and cody anderson. Osa high speed gesi electroabsorption modulator at 1550. Optically controlled electroabsorption modulators for unconstrained wavelength conversion v. An alloptical linearization scheme in a serially cascaded eam using different derivative signs of the transfer function of an eam is. When optical designers attempt to compare the performance of optical systems, a commonly used measure is the modulation transfer function mtf. The saturation characteristics of the dc transfer curve give rise to the superlinear, linear, and sublinear properties of output signal levels against the input signal levels. Lecture notes 9 spatial resolution stanford university. Simulation of traveling wave electroabsorption modulators for.
The nonlinear transfer functions result from the saturation of the ea. How deltasigma adcs work, part 1 analog techniques have dominated signal processing for. Characterization of an electroabsorption modulator. The use of eams for doublet pulse generation has not been reported due to the difficulty of producing a ushaped electricaltooptical eo transfer function. Here we demonstrate an electroabsorption modulator based on an indium tin oxide layer, whose dynamic range is used as nonlinear activation function of a photonic neuron. Optical signal processing using electroabsorption modulators. The input waveguide is split up into two waveguide interferometer arms. Whatever density of output quantization noise is lower, snr would be higher. The modulator has a broad operating wavelength range of 35 nm and a 3 db bandwidth of 40. An activation function is a nonlinear function that is applied to the weighted sum of the inputs of a neuron fig. The transfer function of an amplitude modulator between crossed polarizers is a sin2 function. Electroabsorption modulators used for alloptical signal processing and labelling. Now that the components of the modulation transfer function mtf, resolution and contrast modulation, are defined, consider mtf itself.
Ultraviolet electroabsorption modulators based on bulk gan. Heterodyne technique for measuring the amplitude and phase transfer functions of an optical modulator francis p. The nonlinearityof the activation function allows the network to convergeintode. The bulk modulators provide dramatically improved performance over the devices of ref. Nonlinear properties of travelingwave electroabsorption modulator jongin shim, member, ieee, bin liu, joachim piprek, senior member, ieee, and john e. Index termschirp, electroabsorption, modulation, optical in terferometry. It is a quadrature modulator that is able to operate with an output frequency range of 7002700 mhz.
Javier romerovivas, aidan meehan and lukasz krzczanowicz optical communications research group, dept. Polarization dependence of the intensity modulation transfer function of an optical system with pmd and pdl avishay eyal, member, ieee, david kuperman, oscar dimenstein, and moshe tur, fellow, ieee abstract theintensitymodulation transferfunction ofa linear optical system is described usinga timedependent mullerlikematrix. A low power 2x28 gbs electroabsorption modulator driver array with onchip duobinary encoding renato vaernewyck, xin yin, jochen verbrugghe, guy torfs, xingzhi qiu, efstratios kehayas, nonmembers, and johan bauwelincka, member summary an integrated 2x28 gbs dualchannel duobinary driver ic is presented. In order to understand the significance of mtf, consider some general principles and practical examples for. High speed electroabsorption modulator in the generic photonic integration platform m.
In both types of devices, the absorption edge at room temperature is dominated by excitonic effects and can be strongly modi. Figure 3 shows the optical s21 amplitude transfer response as a function of optical input modulation frequency. Dang thanh bui 1, chi thanh nguyen 2, isabelle ledouxrak 2, joseph zyss 2 and bernard journet 1. Generating digital coefficients from the modulator. Novel bias control of electroabsorption waveguide modulator. Sp2 high speed packaged electroabsorption modulators for. Heterodyne technique for measuring the amplitude and. Electroabsorption modulators used for alloptical signal. Oct 04, 20 for the love of physics walter lewin may 16, 2011 duration. Instrumentation system for determination and compensation. In physics, the machzehnder interferometer is a device used to determine the relative phase shift variations between two collimated beams derived by splitting light from a single source. The incoming light is split into two branches, different phase shifts applies to each path, and then recombined. A simplified optoelectronic 3r regenerator without electrical signal processing is demonstrated by utilizing the nonlinear electrooptical transfer function of an electroabsorption modulator.
Electroabsorption modulators based on bulk gan films and gan. It is the contrast at a given spatial frequency relative to low frequencies. Neuromorphic photonics with electroabsorption modulators. High speed electroabsorption modulator in the generic. Packaging of high speed electroabsorption modulators involves two primary considerations, the coupling of light into and out of the modulator, and the transfer of the rf drive signal to the modulator. A technique is presented for measuring the optical phase transfer function of optoelectronic devices for stimulus frequencies from 100 mhz up to the modulation bandwidth of the device. Bowers, fellow, ieee abstractwe report the nonlinear properties of travelingwave electroabsorption modulators experimentally and theoretically. The large signal model for electroabsorption modulators is studied and. It is shown in the study that the creation of a ushaped eo transfer function from. Electroabsorption modulators based on bulk gan films and.
Electroabsorption modulators used for alloptical signal processing and labelling xu, lin publication date. Travelingwave electroabsorption modulators by shengzhong zhang the transmission bit rates in backbone telecommunication optical fibers are increasing rapidly, motivated by the explosive growth of internet traffic. Loop stability analysis of voltage mode buck regulator with different output capacitor types continuous and discontinuous modes daniel meeks. Instrumentation system for determination and compensation of. The weighting mechanism relies on microring resonator banks as proposed by tait et al. Modulation transfer function mtf magnitude of the complex otf phase transfer function ptf phase of the complex otf 1. Location of loop filters zeros and poles in first and second order of sigmadelta modulator has been fixed.
A machzehnder modulator is used for controlling the amplitude of an optical wave. Index termsanalog systems, electroabsorption, intermodulation distortion, modulation transfer functions, modulators, optical links. If a voltage is applied across one of the arms, a phase shift is induced for the wave passing through that arm. Modulation transfer function radiology reference article. The activation function was replaced with a custom designed nonlinear transfer function resulting from our ab initio ito based electroabsorption modulator model.
Modulator transfer function how is modulator transfer. Optically controlled electroabsorption modulators for. An electroabsorption modulator eam modulates the amplitude of light thanks to the change in the absorption coefficient of a semiconductor material with an applied external electric field. The phase as a functions of the bias voltage characterizes completely the chirpproperties of the modulator when the time dependence of the voltage is known. The most common external modulator is a machzehnder mz device constructed on a lithium niobate linbo 3 substrate. A transmitter for an optical communication system, the transmitter is a a laser that produces light at the output. A low power 2x28 gbs electroabsorption modulator driver. Two phase modulators can be placed in parallel using an interferometric structure. An electroabsorption modulator eam is designed to optimize dynamic range performance over 20 ghz bandwidth. Nonlinear properties of travelingwave electroabsorption. Highopticalpower operation of the electroabsorption. Modeling of machzehnder and electroabsorption modulator pulse generators and extraction of the chirp factor michael j. Optical transfer function otf modulation transfer function. Index termschirp, electroabsorption, modulation, optical in.
Linear optical modulation in a serially cascaded electroabsorption modulator linear optical modulation in a serially cascaded electroabsorption modulator sohn, sung. Its principle of operation is based on the franzkeldysh effect, i. In this work, we extend this concept further to realize a. We report the nonlinear properties of travelingwave electroabsorption modulators experimentally and theoretically. Modulators for nonlinear activation to set the context for the discussion of electrooptic modulators for nns, in this work we are. Published 8 november 2011 2011 iop publishing ltd measurement science and technology, volume 22, number 12. In the time domain, the 1bit adc digitizes the signal to a coarse, 1bit output code. Electroabsorption modulator nmechanisms franzkeldysh effect nobserved in conventional bulk semiconductors quantumconfined stark effect qcse nquantum well structures nboth of these electroabsorption effects are. Bowers electrical engineering department, university of california, santa barbara, ca 93106 abstract electroabsorption modulators eams based on the quantum con.
Dynamic range improvement of electroabsorption modulator by. Simulation of traveling wave electro absorption modulators. The mtf of a lens, as the name implies, is a measurement of its ability to transfer contrast at a particular resolution from the object to the image. High speed packaged electroabsorption modulators for optical communications aaron e. Onorbit modulation transfer function mtf measurements. As the channel bit rate distance product increases, external modulation of the laser light. We say the system provides a signal transfer function stf equal to z1 and a noise transfer function ntf equal to 1z1. Pdf heterodyne technique for measuring the amplitude and. High speed packaged electroabsorption modulators are. Dynamic range improvement of electroabsorption modulator by optical amplification dynamic range improvement of electroabsorption modulator by optical amplification sohn, sung. Instrumentation system for determination and compensation of electrooptic modulator transfer function drift.
An electroabsorption modulator eam is a semiconductor device which can be used for modulating the intensity of a laser beam via an electric voltage. Mtf is used for components as simple as a spherical singlet lens to those as complex as a multielement telecentric imaging lens assembly. The transfer function to each output is very nearly sinusoidal, as illustrated in figure 4. On the radiogram, objects having different sizes and opaci. Generating digital coefficients from the modulator transfer function once you have measured or modeled the modulator transfer function, you can have the venable system software generate the coefficients for the target processor to define the compensation for your desired loop. Heterodyne technique for measuring the amplitude and phase.
Eams have excellent properties such as their small size, large bandwidth, low driving voltage, high extinction ratio, and potential for monolithic integration with other semiconductor components. Polarization dependence of the intensity modulation. The nonlinear activation mechanism is based on a photodiode, which integrates the weighed products, and whose photovoltage drives the elecroabsorption modulator. Most electroabsorption modulators are made in the form of a waveguide with electrodes for applying an electric field in a direction perpendicular to the modulated light beam.
To determine the output noise spectrum, we replace in 1z1 z. The single stripe waveguide enables an extremely compact and integrated package to be fabricated with single mode fiber pigtails. The dynamic behavior of the transmission curves for a wide range of the input radiofrequency signal. The small signal gain of the link is related to the first derivative of the modulators transfer function. An electroabsorption modulator or electroabsorption modulator is a semiconductor device which can be used for controlling modulating the intensity of a laser beam via. Hvam abstract in this letter, we propose a technique based on heterodyne detection for accurately and simultaneously measuring the amplitude and phase transfer functions of an optical. A new optimization of noise transfer function of sigma. Electroabsorption modulator performance predicted from band. Modulation transfer function the resolution and performance of an optical microscope can be characterized by a quantity known as the modulation transfer function mtf, which is a measurement of the microscopes ability to transfer contrast from the specimen to the. As an electrooptic device, characterizing an electroabsorption modulator requires both electrical and optical simulations. Balanced electroabsorption modulator for highlinearity. But in high order loop filter, by changing location of zeros and poles, density of output quantization noise will be changed. Simplified optoelectronic 3r regenerator using nonlinear. Electroabsorption modulator performance predicted from.
The manner in which these issues are addressed is shown in figure 7, where a view of the modulator package with the top removed is shown. Electroabsorption modulator performance predicted from bandedge absorption spectra of bulk, quantumwell, and quantumwellintermixed ingaasp structures gordon b. Coldren b a apogee photonics, 6580 snow drift road, suit 100, allentown, pa. Heterodyne technique for measuring the amplitude and phase transfer functions of an optical modulator article pdf available in ieee photonics technology letters 145. Electroabsorption modulators eams have been instrumental in achieving. The demonstrated device has a compact active region of 1. Linear optical modulation in serially cascaded electroabsorption modulator. A3 general block diagram of a buck converter with dcm modulator and filter transfer functions. Such an architecture is amenable to scalability to two dimensions, allowing the possibility of creating a multichannel wavelengthconverting crossbar switch.
It features a modulation bandwidth from dc to 160 mhz and a noise floor of. Electronic and computer engineering, university of limerick, limerick, ireland. The transfer function s shape permits suppression of higher order intermodulation products, yielding a. Osa ultrawideband doublet pulse generation based on a. When used as a linear transmitter for cable television distribution, the predictable symmetric curvature of the transfer function which causes large oddorder distortion products is compensated for by predistortion in the driver circuit. Sp2 high speed packaged electroabsorption modulators. Electroabsorption modulator integrated distributed feedback. Rp photonics encyclopedia electroabsorption modulators. Leijtens 1 1 cobra research institute, eindhoven university of technology, p. The modulation transfer function mtf is the spatial frequency response of an imaging system or a component. In this work, we extend this concept further to realize a simplified optoelectronic 3r regenerator. Slope efficiency and dynamic range of travelingwave. Electroabsorption, modulator, optical processing, ultrafast dynamics.
The paper presents a new device for analog optical links, the balanced electroabsorption modulator, to allow the simultaneous cancellation of laser relative intensity noise, all evenorder distortions, and third order intermodulation. The transfer functions shape permits suppression of higher order intermodulation products, yielding a spurfree dynamic range exceeding that of. Jun 05, 2000 dynamic range improvement of electroabsorption modulator by optical amplification dynamic range improvement of electroabsorption modulator by optical amplification sohn, sung. Since the transfer function of semiconductor optical amplifier soa is inverse to that of eam, the intermodulation distortion of eam can be reduced by using soa that connect with eam in series. Dynamic range improvement of electroabsorption modulator. Itobased electroabsorption modulator for photonic neural. In conclusion, our results show that itobased electroabsorption modulators offer a significantly higher modulation dynamic range and efficiency with respect to similar siliconbased devices and hence are suitable for implementing the nonlinear activation functions in. Pdf impact of electroabsorption modulator integrated laser on. It is reiterated that a 2r regenerator can not reduce the. So it is possible to compensate completely the effects of the modulator transfer function drift for more than 8.
Optical transfer function otf modulation transfer function mtf the optical transfer function otf is a complexvalued function describing the response of an imaging system as a function of spatial frequency. It is shown that the eml transfer function the ofdm symbols can be constructed within or modulation response is dependent on temperature. Bond, gleb shtengel, prashant singh, yuliya akulova, and c. Balanced electroabsorption modulator for highlinearity, low. Introduction to modulation transfer function edmund optics. Analysis of multiquantum well electroabsorption modulators. An alternative photonicgeneration scheme of ultrawideband uwb doublet pulses based on a semiconductor electroabsorption modulator eam is proposed. Nonlinearity of electroabsorption modulator eam resulting from its near exponential transfer function decreases snr in analog optical transmission. In an external modulator, thetransmission is controlledby theapplied bias. You can achieve linear amplitude modulation with small modulation voltages by biasing the modulator at the 50% transmission point, either with a quarterwave plate or by applying a dc voltage to the modulator. Although monolithic electroabsorption modulated lasers eml have been successfully demonstrated for highperformance digital applications 6, the higher. Analysis of multiquantum well electroabsorption modulators joachim piprek, yijenchiu, and john e.
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