Linearity improvement in photodetectors by using index-matching layer extensions

Murthy, S.; Jung, Thomas; Wu, Ming C.; Wang, Z.; Hsin, Wei

doi:10.1109/leos.2002.1159360

Cited by 3 publications

(4 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Index matching layers (Figure 3.11) have been proposed as a means to increase the responsivity and reduce the length of waveguide coupled lumped element photodetectors [29]. By varying the matching layer extension in front of the photodiode, the absorption profile can be tailored to improve the linearity of the device without sacrificing bandwidth [30]. …”

Section: Parallel Optical Feed Photodetectorsmentioning

confidence: 99%

See 1 more Smart Citation

High‐Power Distributed Photodetectors for RF Photonic Applications

Iezekiel

2009

Microwave Photonics

View full text Add to dashboard Cite

Photodetector linearity is of paramount importance in external intensity modulated direct detection (IMDD) analogue fibre-optic links. This realization has created a demand for high bandwidth, high saturation current photodetectors. Additionally, high current photodetectors have the potential to simplify receiver designs by eliminating the need for impedance matched electronic amplifiers. Applications that can benefit from high-performance photodetectors include antenna remoting, fibre-radio and terahertz signal generation by photomixing.The system level benefits of high current photodetectors may be seen by plotting the link RF gain (G RF ), noise figure (NF), and spurious free dynamic range (SFDR) versus photocurrent for a hypothetical external IMDD link. The curves in Figure 3.1 clearly demonstrate the benefits of high current photodetectors. As the photocurrent increases so does the link performance until laser RIN dominates the noise floor. Link performance may be further improved by utilizing balanced detection, in which case laser RIN is suppressed, the shot-noise limited regime is extended, and with increasing photocurrent, G RF , NF and SFDR improve dramatically.Space charge effects and thermal runaway are the primary factors limiting photodetector high power operation [1]. Large photocurrent density in the absorption regions can screen the applied electric field leading to a lowering of the photogenerated carrier velocity and, ultimately, the complete collapse of the applied electric field [2]. Consequently, RF photoresponse decreases and nonlinearities generated by the photodetector start to degrade the system dynamic range. Microwave Photonics: Devices and Applications Edited by Stavros Iezekiel

show abstract

Section: Parallel Optical Feed Photodetectorsmentioning

confidence: 99%

“…Detectors A and B had identical RC limited bandwidths of 30 GHz, but detector B exhibited nearly an order of magnitude improvement in RF response at 20 GHz[30].…”

mentioning

confidence: 99%

High‐Power Distributed Photodetectors for RF Photonic Applications

Iezekiel

2009

Microwave Photonics

View full text Add to dashboard Cite

show abstract

“…A 0.4-m-thick InGaAsP ( m) matching layer is inserted between the passive waveguide and the absorption region to enhance the optical coupling. The extension of the matching layer beyond the diode can be optimized for high responsivity [25] or for high linearity [26]. The lengths of the diodes in our photodetector are 8, 10, and 20 m, respectively.…”

Section: B Epitaxial Layer Designmentioning

confidence: 99%

Backward-wave cancellation in distributed traveling-wave photodetectors

Murthy

Kim

Jung

et al. 2003

J. Lightwave Technol.

Self Cite

View full text Add to dashboard Cite

This paper describes the design, fabrication, and measurement of backward-wave-cancelled distributed traveling-wave photodetectors. One of the fundamental issues in traveling-wave photodetectors is the generation of backward-waves, which reduces bandwidth or, in the case of matched input termination, reduces their radio-frequency (RF) efficiencies by up to 6 dB. We report a traveling-wave photodetector with multisection coplanar strip transmission lines. The reflections at the discontinuities of the transmission line cancel the backward propagating waves exactly. The bandwidth reduction due to backward-waves is eliminated without sacrificing the RF efficiency. We have demonstrated a broadband backward-wave-cancelled traveling-wave photodetector with three discrete photodiodes. The photodetector is realized in InGaAs/InGaAsP/InP material systems and operates at 1.55 m. A 3-dB bandwidth of 38 GHz and a linear RF output of 1 dBm at 40 GHz have been achieved. The experimental results agree very well with the theoretical calculations. Index Terms-Backward-wave cancellation, coplanar transmission line, distributed photodetectors, high-power photodetectors, microwave photonics, traveling-wave photodetectors, velocity matched distributed photodetectors. I. INTRODUCTION T RAVELING-WAVE photodetectors (TWPDs) have attracted much attention recently [1]-[12]. The speed of conventional lumped element photodetectors is limited by RC time and carrier transit time. By embedding the photodetector in a microwave transmission line, the capacitance of the photodiode becomes part of the distributed capacitance of the transmission line, and the RC time associated with the line impedance and the diode capacitance is eliminated. This enables us to build photodetectors with higher speed, or, perhaps more importantly, high-speed photodetectors with large absorption volume for high power operation. There are two main applications of TWPDs: the first is generation of widely tunable millimeter and submillimeter waves or even Manuscript received

show abstract

“…To obtain a high output saturation current, several photodetector technologies based on properly designed edge-coupled structures have been demonstrated to enhance power-bandwidth products. By reducing the optical modal absorption constant [11] or by achieving uniform photoabsorption [12] in edge-coupled structures with long device-absorption lengths, the output saturation current can be improved in a waveguide photodetector (WGPD) or traveling-wave photodetector (TWPD) [11], [13]. To avoid serious electrical bandwidth degradation in these devices having large areas (length), superior microwave-guiding electrode structures are necessary.…”

mentioning

confidence: 99%

Design and Analysis of Separate-Absorption-Transport-Charge-Multiplication Traveling-Wave Avalanche Photodetectors

Shi

Liu

2004

J. Lightwave Technol.

View full text Add to dashboard Cite

This paper proposes a novel type of avalanche photodiode-the separate-absorption-transport-charge-multiplication (SATCM) avalanche photodiode (APD). The novel design of photoabsorption and multiplication layers of APDs can avoid the photoabsorption layer breakdown and hole-transport problems, exhibit low operation voltage, and achieve ultra-high-gain bandwidth product performances. To achieve low excess noise and ultra-high-speed performance in the fiber communication regime (1.3 1.55 m), the simulated APD is Si-based with an SiGe-Si superlattice (SL) as the photoabsorption layer and traveling-wave geometric structures. The frequency response is simulated by means of a photo-distributed current model, which includes all the bandwidth-limiting factors, such as the dispersion of microwave propagation loss, velocity mismatch, boundary reflection, and multiplication/transport of photogenerated carriers. By properly choosing the thicknesses of the transport and multiplication layers, microwave propagation effects in the traveling-wave structure can be minimized without increasing the operation voltage significantly. A near 30-Gb/s electrical bandwidth and 10 avalanche gain can be achieved simultaneously, even with a long device absorption length (150 m) and low operation voltage ( 12 V). In addition, the ultrahigh output saturation power bandwidth product of this simulated TWAPD structure can also be expected due to the large photoabsorption volume and superior microwave-guiding structure. Index Terms-Avalanche photodetector, avalanche photodiode (APD), high gain-bandwidth-product avalanche photodetector, high-saturation-power photodetector, Si-SiGe-based photodetector, Si-SiGe-based superlattice (SL), traveling-wave photodetector, ultra-high-speed photodetector. I. INTRODUCTIONT HE rapid growth in Internet traffic has created an urgent need to increase the channel bandwidth capacity of fiber-optic communication systems. As a key component in these transmission systems, ultra-high-speed photodetectors are able to not only increase the transmission capability in a single channel, but also reduce the required number of channels and complexity of management in a wavelength-division-multiplexing (WDM) fiber communication system [1]. There

show abstract

Linearity improvement in photodetectors by using index-matching layer extensions

Cited by 3 publications

References 6 publications

High‐Power Distributed Photodetectors for RF Photonic Applications

High‐Power Distributed Photodetectors for RF Photonic Applications

Backward-wave cancellation in distributed traveling-wave photodetectors

Design and Analysis of Separate-Absorption-Transport-Charge-Multiplication Traveling-Wave Avalanche Photodetectors

Contact Info

Product

Resources

About