High-power high-speed photodetectors-design, analysis, and experimental demonstration

Lin, L.Y.; Wu, Ming C.; Itoh, T.; Vang, T.; Muller, Richard E.; Sivco, Deborah L.; Cho, A.Y.

doi:10.1109/22.618430

Cited by 141 publications

(58 citation statements)

References 24 publications

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“…This definition of compression is used here and is appropriate for quadrature-biased externally modulated links or other systems where predominantly high average currents are encountered. Alternative definitions of compression for pulsed [18] or large-signal [22] CW conditions are more appropriate for those particular applications and will not be considered here. Direct comparisons betweenmeasurements and measurements based on these alternative definitions should be avoided as pulsed compression measurements tend to result in much higher compression currents and are dependent on pulse width [23] while large-signal compression measurements typically lead to lower compression currents [22] due to the higher peak currents.…”

Section: General Considerationsmentioning

confidence: 99%

“…A two-laser heterodyne system [20] has been used to characterize PD nonlinearities [3], [20], [21] as well as the large-signal saturation behavior [22], and pulsed systems [17], [18], [23] are helpful in studying the transient behavior. Small-signal measurement systems have also been used to measure certain characteristics [6], [7], [11], [14], [22]- [24] of high-current PD's.…”

Section: General Considerationsmentioning

confidence: 99%

“…This point is particularly important in optically steered phased array antennas since any increase in photodetector output signal level reduces the necessary phase-and amplitude-matched electronic gain at each antenna element. In an effort to increase the output photocurrent, a number of groups have been studying surface-illuminated [6]- [11], metal-semiconductor-metal [12], [13], waveguide [14], [15], traveling-wave [16], [17], and photodetector arrays [18], [19]. The ability to increase photocurrent depends on two primary factors: 1) space-charge limitations which are influenced by physical dimensions, structure type, illumination conditions, maximum electric field, etc.…”

Section: Introductionmentioning

confidence: 99%

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Design considerations for high-current photodetectors

Williams

Esman

1999

J. Lightwave Technol.

179

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Abstract-This paper outlines the design considerations for gigahertz-bandwidth, high-current p-i-n photodiodes utilizing InGaAs absorbers. The factors being investigated are photodetector intrinsic region length, intrinsic region doping density, temperature effects, illumination spot size, illumination wavelength, frequency, and illumination direction. Space-charge calculations are used to determine optimal device geometry and conditions which maximize saturation photocurrent. A thermal model is developed to study the effects of temperature on high-current photodetector performance. The thermal and space-charge model results are combined to emphasize the importance of thin intrinsic region lengths to obtain high current. Finally, a comparison between surface-illuminated p-i-n structures and waveguide structures is made to differentiate between the problems associated with achieving high current in each structure and to outline techniques to achieve maximum performance.

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Section: General Considerationsmentioning

confidence: 99%

Section: General Considerationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Design considerations for high-current photodetectors

Williams

Esman

1999

J. Lightwave Technol.

179

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“…The terahertz power can be confined on-chip or radiated for quasi-optical propagation and collection by a receiver. In addressing a number of concerns related to traveling-wave photodetectors, I draw on extensive work done on traveling-wave photodetectors designed for lower frequency operation [63,64,65,66,67,68,69].…”

Section: Terahertz Photomixersmentioning

confidence: 99%

Distributed photomixers

Duerr

McIntosh

Verghese³

2000

Conference on Lasers and Electro-Optics (CLEO 2000). Technical Digest. Postconference Edition. TOPS Vol.39 (IEEE Cat. No.00CH37

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Although the terahertz domain has been explored scientifically, components, especially sources, are needed to enable further exploration of the frequency range. A photomixer generates coherent THz radiation through optical heterodyne down-conversion. A terahertzfrequency beat signal on an optical carrier illuminates an ultrafast photoconductor, modulating the conductance. The time-varying conductance together with a constant voltage bias generates time-varying current at the beat frequency. Low-temperature-grown gallium arsenide (LTG-GaAs) is the photoconductive material of choice, because its short carrier lifetime allows the conductance to be efficiently modulated at THz frequencies.The distributed photomixer described in this thesis is a new style of LTG-GaAs photomixer which uses an optical waveguide to couple the beat signal to an active area which is large relative to the terahertz wavelength. This large, traveling-wave mode active area distributes the heat load from absorbed optical power and ohmic heating from photocurrent and avoids the ¡ £ ¢ rolloff associated with a lumped-element photomixer's intrinsic capacitance and the load resistance. The distributed photomixer structure consists of coplanar strips (CPS) fabricated on top of a dielectric strip-loaded waveguide that guides the optical beat. The conductance of a thin layer of LTG-GaAs between the CPS and optical guide is modulated by the weakly coupled optical signal. The THz conductance wave between the dc-biased CPS creates a THz electromagnetic wave which propagates along the CPS. To velocity match the THz and optical waves, the CPS are periodically loaded with thin electrodes that add a small shunt capacitance to the line. The CPS are terminated in a planar antenna that radiates the THz wave.This thesis describes the design, fabrication, and testing of waveguide-coupled distributed photomixers. The photomixers demonstrated in this thesis operated in travelingwave mode and produced 100 nW of power at 0.3 THz and the power output rolled off at 6 dB/octave until 1.4 THz. A model which qualitatively and quantitatively predicts the device performance as a function of frequency, illumination and voltage bias is developed. A general design methodology, detailed discussion of fabrication steps and possible methods to increase output power are also presented.

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“…Several approaches have been proposed to increase the maximum linear photocurrent of high-speed PDs, including wave-guide PDs with low confinement factors [4]- [6], traveling-wave photodetectors [7], [8] phototransistors [9], uni-traveling-carrier photodiode [10], and velocity-matched distributed photodetectors (VMDP) [11]- [13], and parallel fed VMDP [14]. Using the VMDP with metal-semiconductor-metal (MSM) PDs, we have previously achieved a saturation photocurrent of 33 mA at 1.55-m wavelength [15].…”

mentioning

confidence: 99%

Velocity-matched distributed photodetectors and balanced photodetectors with p-i-n photodiodes

Islam

Murthy

Itoh

et al. 2001

IEEE Trans. Microwave Theory Techn.

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Abstract-We report on the first demonstration of velocity-matched distributed photodetectors and balanced photodetectors with p-i-n photodetectors. Record-high linear dc photocurrent of 45 mA has been achieved without suffering from thermal damage, thanks to the superior power handling capability of p-i-n photodiodes. A novel fiber alignment technique has been developed to achieve high linear photocurrent. More than 37 dB of common-mode-rejection ratio and 45-dB suppression of laser relative intensity noise over a broad frequency range have been achieved using the distributed balanced photodetectors in an RF fiber-optic link. The frequency response is flat from 1 to 35 GHz.

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High-power high-speed photodetectors-design, analysis, and experimental demonstration

Cited by 141 publications

References 24 publications

Design considerations for high-current photodetectors

Design considerations for high-current photodetectors

Distributed photomixers

Velocity-matched distributed photodetectors and balanced photodetectors with p-i-n photodiodes

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