Interband GaSb-based laser diodes for spectral regions of 2.3-2.4 µm and 3-3.1 µm with improved room-temperature performance
Author(s):
Gregory Belenky;
Dimitri Donetski;
Leon Shterengas;
Takashi Hosoda;
Jianfeng Chen;
Gela Kipshidze;
Michail Kisin;
David Westerfeld
Show Abstract
The paper describes the heterostructures and device output parameters of Type-I quantum-well (QW) laser diodes with
InGaAsSb active regions designed for room-temperature operation near 2.3 μm and 3.1 μm. For both designs decrease of
the threshold current density and increase of the room-temperature output power have been achieved with increase of the
QW depth for holes. For the 2.3 μm laser diodes, confinement of holes in the QW embedded into the AlGaAsSb
waveguide was improved with increase of the hole energy level with compressive strain. Arrays of 1-mm-long 100-μmwide
laser diode emitters with a fill-factor of 30 % have been fabricated. A quasi-CW (30 μs, 300 Hz) output power of
16.7 W from a 4-mm-wide array has been obtained with conductive cooling. For the laser diodes designed for roomtemperature
operation above 3 μm, the hole confinement was improved by lowering the valence band energy in the
waveguide. Two approached were implemented: one with increase of the Al composition, and another with utilization of
quinternary InAlGaAsSb waveguide with increased As composition compared to the conventional AlGaAsSb
waveguide. With the quinternary waveguide approach, a room-temperature CW output power in excess of 130 mW and
a threshold current as low as 0.6 A have been obtained at λ = 3 μm from 2-mm-long 100-μm-wide emitters.
Type-II superlattices and quantum cascade lasers for MWIR and LWIR free-space communications
Author(s):
Andrew Hood;
Allan Evans;
Manijeh Razeghi
Show Abstract
Free-space optical communications has recently been touted as a solution to the "last mile" bottleneck of
high-speed data networks providing highly secure, short to long range, and high-bandwidth connections. However,
commercial near infrared systems experience atmospheric scattering losses and scintillation effects which can adversely
affect a link's operating budget. By moving the operating wavelength into the mid- or long-wavelength infrared
enhanced link uptimes and increased operating range can be achieved due to less susceptibility to atmospheric affects.
The combination of room-temperature, continuous-wave, high-power quantum cascade lasers and high operating
temperature type-II superlattice photodetectors offers the benefits of mid- and long-wavelength infrared systems as well
as practical operating conditions for next generation free-space communications systems.
Recent advances in long wavelength quantum dot based lasers
Author(s):
A. Ramdane;
A. Martinez;
S. Azouigui;
D.-Y. Cong;
K. Merghem;
A. Akrout;
C. Gosset;
G. Moreau;
F. Lelarge;
B. Dagens;
J.-G. Provost;
A. Accard;
O. Le Gouezigou;
I. Krestnikov;
A. Kovsh;
M. Fischer
Show Abstract
This paper presents recent progress in the field of semiconductor lasers based on self-assembled quantum dots grown
either on GaAs or InP substrates.
Quantum dot (QD) based lasers are attracting a lot of interest owing to their remarkable optoelectronic properties that
result from the three dimensional carrier confinement. They are indeed expected to exhibit much improved performance
than that of quantum well devices. Extremely low threshold currents as well as high temperature stability have readily
been demonstrated in the InAs/GaAs material system.
The unique properties of quantum dot based active layers such as broad optical gain spectrum, high saturation output
power, ultrafast gain dynamics and low loss are also very attractive for the realization of mode-locked lasers.
Recent results in the field of directly modulated InAs/GaAs lasers emitting in the 1.3 μm window are discussed. We
report in particular on temperature independent linewidth enhancement factor (or Henry factor αH) up to 85°C. This is a
key parameter which determines many laser dynamic properties. Optical feedback insensitive operation of specifically
band-gap engineered devices, compatible with high bit rate isolator-less transmission is also reported at 1.55 μm.
Monolithic mode locked lasers based on InAs/InP quantum dashes have been investigated for 1.55 μm applications. Subpicosecond
pulse generation at very high repetition rates (> 100 GHz) is reported for self-pulsating one-section Fabry
Perot devices. Specific applications based on these compact pulse generators including high bit rate clock recovery are
discussed.
Controlled emission of polarized infrared light by a nanocavity equipped optical source
Author(s):
K. Ikeda;
H. T. Miyazaki;
T. Kasaya;
K. Yamamoto;
Y. Inoue;
K. Fujimura;
T. Kanakugi;
M. Okada;
K. Hatade
Show Abstract
This paper presents the development of a nanofabricated mid-infrared optical source, thermally emitting linearly
polarized light. The optical source in the current study is a heated series of one-dimensional metal-insulator-metal
cavities with a closed end on a Au surface. This closed cavity exhibits the so-called organ pipe resonance resulting in
specific frequencies being selectively emitted from the blackbody heat source. This characteristic results in the control of
the thermal radiation, thereby emitting a narrow infrared spectrum at a specific wavelength of 2.5-5.35 micro-meters.
The wavelength is specified by a theoretical model and 100nm wide, 1000nm deep dimensions of the cavity were
accurately manufactured. The maximum emittance reaches 0.90, and the peak width Δλ/λ is as narrow as 0.13-0.23. As
a demonstration, the Cyclohexane concentration in Benzene is determined with a simple optical system. This simple
emitter is expected to play a key role in the infrared sensing technologies for analyzing our environment.
Electrically pumped photonic crystal distributed feedback quantum cascade lasers
Author(s):
Y. Bai;
P. Sung;
S. R. Darvish;
W. Zhang;
A. Evans;
S. Slivken;
M. Razeghi
Show Abstract
We demonstrate electrically pumped, room temperature, single mode operation of photonic crystal distributed feedback
(PCDFB) quantum cascade lasers emitting at λ ~ 4.75 μm. Ridge waveguides of 50 μm and 100 μm width were
fabricated with both PCDFB and Fabry-Perot feedback mechanisms. The Fabry-Perot device has a broad emitting
spectrum and a broad far-field character. The PCDFB devices have primarily a single spectral mode and a diffraction
limited far field characteristic with a full angular width at half-maximum of 4.8 degrees and 2.4 degrees for the 50 μm
and 100 μm ridge widths, respectively.
Overview of quantum cascade laser research at the Center for Quantum Devices
Author(s):
S. Slivken;
A. Evans;
J. Nguyen;
Y. Bai;
P. Sung;
S. R. Darvish;
W. Zhang;
M. Razeghi
Show Abstract
Over the past several years, our group has endeavored to develop high power quantum cascade
lasers for a variety of remote and high sensitivity infrared applications. The systematic
optimization of laser performance has allowed for demonstration of high power, continuous-wave
quantum cascade lasers operating above room temperature. In the past year alone, the efficiency
and power of our short wavelength lasers (λ~4.8 μm) has doubled. In continuous wave at room
temperature, we have now separately demonstrated ~10% wallplug efficiency and ~700 mW of
output power. Up to now, we have been able to show that room temperature continuous wave
operation with >100 mW output power in the 3.8< λ<11.5 μm wavelength range is possible.
Toward regulated photon generations from semiconductor quantum dots and their applications
Author(s):
I. Suemune;
H. Kumano;
Y. Hayashi;
K. Tanaka;
T. Akazaki;
M. Jo;
Y. Idutsu
Show Abstract
Quantum information processing and quantum cryptography are expected to realize highly secure future information
networks. How to control photon qubits will be one of the major issues for this direction, but the technologies related to
generations and detections of individual photons are still being developed. Semiconductor quantum dots (QDs) have
been expected to play major role for on-demand generations of single photons as well as entangled photon pairs. In this
talk, photon generation processes from a single QD will be studied for the control of the quantum states of generated
photons. Generation of entangled photon pairs from QDs based on biexciton-exciton cascade recombination processes is
presently in a difficult situation due to exciton states energy splitting related to growth-related issues. An approach to
open new paradigm will be discussed with preliminary results.
Mid-infrared vertical-cavity surface-emitting lasers based on lead salt/BaF2 Bragg mirrors
Author(s):
Martin Eibelhuber;
Thomas Schwarzl;
Andreas Winter;
Harald Pascher;
Wolfgang Heiss;
Gunther Springholz
Show Abstract
We demonstrate mid-infrared continuous-wave vertical-cavity surface-emitting lasers based on Bragg mirrors using
IV-VI semiconductors and BaF2. This material combination exhibits a high ratio between the refractive indices of up to
3.5, leading to a broad mirror stop band with a relative width of 75 %. Thus, mirror reflectivities higher than 99.7 % are
gained for only three layer pairs. Optical excitation of microcavity laser structures with a PbSe active region results in
stimulated emission at various cavity modes between 7.3 μm and 5.9 μm at temperatures between 54 K and 135 K. Laser
emission is evidenced by a strong line width narrowing with respect to the line width of the cavity mode and a clear laser
threshold at a pump power of 130 mW at 95 K. Furthermore, we study a similar microcavity but without an active
region. The resonance of such an empty microcavity has a narrow line width of 5.2 nm corresponding to a very high
finesse of 750, in good agreement to transfer matrix simulations and to the expected mirror reflectivities.
Type II strained layer superlattice: a potential infrared sensor material for space
Author(s):
L. Zheng;
M. Z. Tidrow;
A. Novello;
H. Weichel;
S. Vohra
Show Abstract
The Missile Defense Agency's Advanced Technology Office is developing advanced passive electro-optical and infrared
sensors for future space-based seekers by exploring new infrared detector materials. A Type II strained layer
superlattice, one of the materials under development, has shown great potential for space applications. Theoretical
results indicate that strained layer superlattice has the promise to be superior to current infrared sensor materials, such as
HgCdTe, quantum well infrared photodetectors, and Si:As. Strained layer superlattice-based infrared detector materials
combine the advantages of HgCdTe and quantum well infrared photodetectors. The bandgap of strained layer
superlattice can be tuned for strong broadband absorption throughout the short-, mid-, long-, and very long wavelength
infrared bands. The electronic band structure can be engineered to suppress Auger recombination noise and reduce the
tunneling current. The device structures can be easily stacked for multicolor focal plane arrays. The III-V semiconductor
fabrication offers the potential of producing low-defect-density, large-format focal plane arrays with high uniformity and
high operability. A current program goal is to extend wavelengths to longer than 14 μm for space applications. This
paper discusses the advantages of strained layer superlattice materials and describes efforts to improve the material
quality, device design, and device processing.
Novel routes in heteroepitaxy and selective area growth for nanophotonics
Author(s):
Sebastian Lourdudoss;
Fredrik Olsson;
Yanting Sun
Show Abstract
Integration of active photonic components on silicon and silicon on insulator (SOI) would be versatile for nanophotonics
since CMOS compatible processes are available for fabricating passive devices on Si/SOI. Selective area growth of III-V
semiconductors is also attractive for realising periodic structures for nanophotonics. Here we report on the recent results
of high quality InP on Si and InP on SOI achieved by means of nanopatterning. MQW structures have been realised on
InP/Si and InP/SOI. We would elaborate routes for monolithic integration of active and passive devices for
nanophotonics.
Type II InSb/InAs quantum dot structures grown by molecular beam epitaxy using Sb2 and As2 fluxes
Author(s):
P. J. Carrington;
V. A. Solov'ev;
Q. Zhuang;
S. V. Ivanov;
A. Krier
Show Abstract
We report the molecular beam epitaxial growth of InSb quantum dots (QD) inserted as sub-monolayers in an InAs matrix
and grown using Sb2 and As2 fluxes. These InSb QD nanostructures exhibit intense mid-infrared photoluminescence up
to room temperature. The nominal thickness of the sub-monolayer insertions can be controlled by the growth
temperature (TGr = 450-320 °C) which gives rise to the variation of the emission wavelength within the 3.6-4.0 μm range
at room temperature. Light emitting diodes where fabricated using ten InSb QD sheets and were found to exhibit bright
electroluminescence with a single peak at 3.8 μm at room temperature. A comparative analysis of the optical properties
of the structures grown using (Sb2,As2) and (Sb4,As4) is also presented.
Advantages of quantum cascade detectors
Author(s):
A. Gomez;
M. Carras;
A. Nedelcu;
E. Costard;
X. Marcadet;
V. Berger
Show Abstract
Quantum cascade detectors (QCDs) have been introduced recently as a photovoltaic candidate to infrared
detection. Since QCDs work with no applied bias, longer integration time and different read-out circuits can
be used. Depending on the application, QCDs could be preferred to QWIPs. The systematic comparison
between QCDs and QWIPs is difficult due to the large number of parameters in a thermal imager for a given
application. Here we propose a first comparison between these two devices, starting with several examples,
based on specific cases. In particular, it is shown that QCDs in the 8-12 µm band are an interesting alternative
to QWIPs if higher operating temperature is required.
Proposal for (110) InAs/GaSb superlattices for infrared detection
Author(s):
F. Szmulowicz;
H. J. Haugan;
G. J. Brown
Show Abstract
This paper discusses the potential attributes of (110)-grown InAs/GaSb superlattices for infrared detection
applications. In comparison to (001)-grown structures, (110) SLs will be thinner, have higher mobilities, diffusion
lengths, quantum efficiencies, and gains. Unless growth issues arise, they should also have higher minority carrier
lifetimes, higher responsivities, lower noise, and higher detectivities. The first 8x8 envelope-function approximation
calculation for a (110)-oriented structure shows the bands to be slightly anisotropic and the oscillator strengths to be
polarization dependent. Layer widths for specific absorption thresholds were calculated.
High-performance focal plane array based on type-II InAs/GaSb superlattice heterostructures
Author(s):
Pierre-Yves Delaunay;
Manijeh Razeghi
Show Abstract
Recent progress in growth techniques, structure design and processing has lifted the performances
of Type-II InAs/GaSb superlattice photodetectors. A double heterostructure design, based on a low band
gap (11 μm) active region and high band gap (5 μm) superlattice contacts, reduced the sensitivity of the
superlattice to surface effects. The heterodiodes with an 11 µm cutoff, passivated with SiO2, presented
similar performances to unpassivated devices and a one order of magnitude increase of the resistivity of the
sidewalls, even after flip-chip bonding and underfill. Thanks to this new design and to the inversion of the
polarity of the devices, a high performance focal plane array with an 11 μm cutoff was demonstrated. The
noise equivalent temperature difference was measured as 26 mK and 19 mK for operating temperatures of
81 K and 67 K. At an integration time of 0.08 ms, the FPA presented a quantum efficiency superior to 50%.
III-nitride photon counting avalanche photodiodes
Author(s):
Ryan McClintock;
Jose Luis Pau;
Kathryn Minder;
Can Bayram;
Manijeh Razeghi
Show Abstract
In order for solar and visible blind III-nitride based photodetectors to effectively compete with the detective
performance of PMT there is a need to develop photodetectors that take advantage of low noise avalanche gain.
Furthermore, in certain applications, it is desirable to obtain UV photon counting performance. In this paper, we
review the characteristics of III-nitride visible-blind avalanche photodetectors (APDs), and present the state-of-the-art
results on photon counting based on the Geiger mode operation of GaN APDs. The devices are fabricated on
transparent AlN templates specifically for back-illumination in order to enhance hole-initiated multiplication. The
spectral response and Geiger-mode photon counting performance are analyzed under low photon fluxes, with single
photon detection capabilities being demonstrated in smaller devices. Other major technical issues associated with the
realization of high-quality visible-blind APDs and Geiger mode APDs are also discussed in detail and solutions to the
major problems are described where available. Finally, future prospects for improving upon the performance of these
devices are outlined.
Broadband photoresponse from InAs quantum dots embedded in a graded well for visible to mid-infrared detection
Author(s):
Brandon S. Passmore;
Jiang Wu;
Eric A. DeCuir Jr.;
Omar Manasreh;
P. M. Lytvyn;
Euclydes Marega Jr.;
Vasyl P. Kunets;
Gregory J. Salamo
Show Abstract
Interband and intersubband transitions in self-assembled InAs quantum dots embedded in an InGaAs graded
well have been investigated for their use in visible to mid-infrared (0.4 - 20 μm) detection applications. The materials
were grown by molecular beam epitaxy and characterized using atomic force microscopy and photoluminescence.
Devices were fabricated from the multiple quantum dot structures in order to measure the normal incident photoresponse
at 77 and 300 K. In addition, the dark current was measured in the temperature range of 77 - 300 K for the devices. A
dual broadband photoresponse from the interband and intersubband transitions was measured to be 0.5 to 1.0 μm and 2.0
to 14.0 μm, respectively.
Interface roughness estimate from carrier transport in InAs/GaSb superlattices
Author(s):
F. Szmulowicz;
S. Elhamri;
H. J. Haugan;
G. J. Brown;
W. C. Mitchel
Show Abstract
The performance of infrared focal plane arrays and quantum cascade lasers manufactured from InAs/GaSb type-
II superlattices (SLs) depends on the mobility of carriers along the growth axis. In turn, the longitudinal mobility
depends on the quality of SL interfaces. In-plane transport is a sensitive measure of interface quality and the degree of
interface roughness scattering (IRS). In this paper, we demonstrate the IRS-limited transport regime in InAs/GaSb SL
samples grown for this study. We find that the in-plane mobility
μ as a function of InAs layer width L behaves as
μ ∝ L5 , which closely follows the classic sixth power dependence expected from theory. Fits to the mobility data
indicate that, for one monolayer surface roughness, the roughness correlation length is about 35 Å.
Progress in MOVPE-growth of InGaN and InN
Author(s):
Takashi Matsuoka
Show Abstract
Nitride-semiconductor light-emitting-devices such as blue, green, and white LEDs, and 400nm-wavlength LDs have
been commercially available since 1993. The active layers in all these devices consist of InGaN, which composition is
designed for the wavelength of the emitted light. In this paper, the current status of MOVPE growth in GaN to InN,
including InGaN is reviewed. The GaN growth mechanism of two-step growth on a sapphire substrate, polarity-
controlled GaN growth, and the possibility in In-rich InGaN growth are described. The InN research as an ultimate
material of InGaN is also introduced. The future perspective of InN in device application is also mentioned.
Design approaches for digitally dominated active pixel sensors: leveraging Moore's Law scaling in focal plane readout design
Author(s):
Brian Tyrrell;
Robert Berger;
Curtis Colonero;
Joseph Costa;
Michael Kelly;
Eric Ringdahl;
Kenneth Schultz;
James Wey
Show Abstract
Although CMOS technology scaling has provided tremendous power and circuit density benefits for innumerable
applications, focal plane array (FPA) readouts have largely been left behind due to dynamic range and signal-to-noise
considerations. However, if an appropriate pixel front end can be constructed to interface with a mostly digital pixel, it
is possible to develop sensor architectures for which performance scales favorably with advancing technology nodes.
Although the front-end design must be optimized to interface with a particular detector, the dominant back end
architecture provides considerable potential for design reuse.
In this work, digitally dominated long wave infrared (LWIR) active pixel sensors with cutoff wavelengths
between 9 and 14.5 μm are demonstrated. Two ROIC designs are discussed, each fabricated in a 90-nm digital CMOS
process and implementing a 256 x 256 pixel array on a 30-μm pitch. In one of the implemented designs, the feasibility
of implementing a 15-μm pixel pitch FPA with a 500 million electron effective well depth, less than 0.5% non-linearity
in the target range and a measured NEdT of less than 50 mK at f/4 and 60 K is demonstrated. Simple on-FPA signal
processing allows for a much reduced readout bandwidth requirement with these architectures.
To demonstrate the potential for commonality that is offered by a digitally dominated architecture, this LWIR
sensor design is compared and contrasted with other digital focal plane architectures. Opportunities and challenges for
application of this approach to various detector technologies, optical wavelength ranges and systems are discussed.
Design and modeling of nanophotonic beam structures as optical NEMS sensors
Author(s):
Chengkuo Lee;
Jayaraj Thillaigovindan;
Aibin Yu;
Rohit Radhakrishnan;
Chii-Chang Chen;
Ya-Ting Chao;
John H. Lau
Show Abstract
Silicon photonic crystal (PhC) waveguide based resonator is designed by introducing a micro-cavity within the line
defect so as to form the resonant band gap structure for PhC. Free-standing silicon beam comprising this nanophotonic
resonator structure is investigated. The output resonant wavelength is sensitive to the shape of air holes and defect length
of the micro-cavity. The resonant wavelength shift in the output spectrum is a function of force loading at the center of a
suspended beam with PhC waveguide resonator. The sensing capability of this new nanomechanical sensor is derived as
that vertical deformation is about 20nm at center and the smallest strain is 0.005% for defect length.
A quantum cascade laser based room temperature spectrometer for sensitive detection of ammonia and ethylene
Author(s):
J. Manne;
W. Jäger;
J. Tulip
Show Abstract
We investigated the use of a pulsed, distributed feedback (DFB) quantum cascade (QC) laser centered at 970 cm-1 in
combination with an astigmatic Herriot cell with 150 m path length for the detection of ammonia and ethylene. This
spectrometer utilizes the intra-pulse method, where a linear frequency down-chirp, that is induced when a top-hat current
pulse is applied to the laser, is used for sweeping across the absorption line. This provides a real time display of the
spectral fingerprint of molecular gases, which can be a few wave numbers wide. A 200 ns long pulse was used for these
measurements which resulted in a spectral window of ~1.74 cm-1. A room temperature mercury-cadmium-telluride
detector was used, resulting in a completely cryogen free spectrometer. We demonstrated detection limits of ~3 ppb for
ammonia and ~5 ppb for ethylene with less than 10 s averaging time.
Sub-diffraction optical imaging by high-spatial-resolution photodetectors and Fourier signal processing
Author(s):
Milad Hashemi;
Michael Hegg;
Babak A. Parviz;
Lih Y. Lin
Show Abstract
With the advance of nano-lithography and nano-fabrication, individual sizes of electronic,
photonic, and mechanical components, as well as their integration densities, have progressed
steadily towards the sub-100 nm regime. Therefore, being able to image such feature sizes
becomes imperative. Many conventional high-resolution imaging tools such as SEM, STM,
AFM, and NSOM either require operation under high vacuum or slow scanning across the
sample. A far-field optical imaging instrument would thus be highly desirable. Optical imaging,
however, is subject to the diffraction limit, which limits the size of the smallest resolvable
feature to be ~ λ/2, where λ is the wavelength of the imaging light. Recently, negative-index materials and super lens have been proposed to overcome this limit and
achieve high-resolution optical imaging [1-4]. In this paper, we propose a different approach to
achieve sub-diffraction optical imaging with far-field microscopy. The technology builds on a
high-spatial resolution quantum-dot (QD) photodetector with high sensitivity that we have
demonstrated [5]. The photodetector consists of several nanocrystal QDs between a pair of
electrodes with 50-nm width spaced ~ 25 nm apart. An optically effective area of 13515 nm2 was
determined by modeling the electric field distribution in-between and around the electrodes using
FEMLab. High-sensitivity photodetection has been demonstrated by measuring the tunneling
photocurrent through the QDs, with a detection limit of 62 pW of the input optical power. The
proposed sub-diffraction optical imaging system consists of an array of such photodetectors. We
performed theoretical simulations assuming a two slit source and then pixilated the far-field
diffraction pattern to simulate the photodetector array. A Fourier transform of the detector signal
is then performed to determine how much of the original aperture information remains. Using a
wavelength of 500 nm and a screen distance of 10 cm, we found that, as expected, the quality of
the resultant image generally degraded with larger pixilation size. With 50-nm one-dimensional
spatial resolution at the detection plane, it appears that the original slit image with 100-nm width
and 300-nm spacing can still be restored.
Multiplexed photon-counting detectors
Author(s):
Sergey V. Polyakov;
V. Schettini;
I. P. Degiovanni;
G. Brida;
Alan Migdall
Show Abstract
We discuss a scheme for a photon-counting detection system that overcomes the difficulties of photon-counting at
extremely high rates. Our method uses an array of N detectors and a 1-by-N optical switch with a control circuit to direct
input light to live detectors. Detector deadtime is significantly reduced by an active routing of single photons to the
detector that has had the most time to recover from its last firing. In addition to deadtime reduction, our scheme reduces
afterpulsing and background counts (such as dark counts). We present experimental results showing the advantageous
performance of our system as compared to passive multi-detector detection systems. We conclude that intelligent active
management of a group of N photon-counting detectors yields the highest photon counting rates, an important
technological challenge for fast developing quantum metrology and quantum key distribution applications. Also, we
report our experimental progress in developing an integrated device based on this scheme.
High efficiency 1.55 µm Geiger-mode single photon counting avalanche photodiodes operating near 0oC
Author(s):
Ping Yuan;
Joseph Boisvert;
Rengarajan Sudharsanan;
Takahiro Isshiki;
Paul McDonald;
Michael Salisbury;
Mingguo Liu;
Joe C. Campbell
Show Abstract
Recent developments in three-dimension imaging, quantum cryptography, and time-resolved spectroscopy
have stimulated interest in single-photon counting avalanche photodiodes (APD) operating in the short wavelength
infrared region. For visible and near infrared wavelengths, Silicon Geiger-mode APDs have demonstrated excellent
photon detection efficiency (PDE) and low dark current rate (DCR)1. Recently, MIT Lincoln Laboratories, Boeing
Spectrolab, and Boeing SVS have demonstrated Geiger-mode (GM) APD focal plane arrays (FPA) operating at 1.06
μm. However for longer wavelength sensitivity around 1.55 μm, GM-APDs have to be cooled to 180~240 K to
achieve a usable DCR. Power consumption, package weight and size and APD PDE all suffer with this cooling
requirement.
In this paper we report the development of an InP/InGaAs GM-APD structure with high PDE and low DCR
at 273K. The photon collection efficiency was optimized with a single step-graded quaternary layer and a 3.5 μm
InGaAs absorption layer, which provides a broadband coverage from 0.95 μm to 1.62 μm. The InP multiplication
layer and the charge layer are carefully tailored to minimize the DCR and maximize the PDE. Despite having a low
bandgap absorber layer InGaAs, these APDs demonstrated excellent dark current, optical responsivity, and superior
DCR and PDE at 1.55 μm. The DCR and PDE were evaluated on 25 μm diameter APDs at 273 K. DCRs as low as
20 kHz have been measured at a 2 V overbias, while PDEs at 1.55 μm exceed 30% at 2 V overbias.
Time-of-flight sensing using time-correlated single-photon counting
Author(s):
Gerald S. Buller;
Aongus McCarthy;
Robert J. Collins;
Philip A. Hiskett;
Veronica Fernandez;
Sergio Hernandez-Marin;
Andrew M. Wallace
Show Abstract
Time-correlated single-photon counting techniques using individual optimized detectors have been applied to
time-of-flight ranging and depth imaging. This paper describes recent progress in photon-counting systems
performing surface mapping of non-cooperative targets. This includes systems designed for short ranges of the
order of 1-50 meters, and longer ranges of up to ten kilometers. The technique has also been applied to distributed
surfaces. We describe the measurement approach, techniques used for scanning, as well as the signal analysis
methodology and algorithm selection.
The technique is fundamentally flexible: the trade-off between the integrated number of counts (or acquisition
time) against range repeatability or depth resolution allows its application in a number of diverse fields. The
inherent time gating of the technique, allied to the spatial filtering provided by small active area single-photon
detectors, can lead to operation under high ambient light conditions even with low average optical power pulsed
sources.
We have demonstrated three-dimensional imaging of meter-dimensioned objects where reverse engineering
methods using cooperative targets cannot be routinely employed: e.g. delicate objects, or objects with more than
one reflective surface. Using more advanced signal processing algorithms, we have been able to improve the system
performance significantly, as measured by the depth resolution at short and long ranges. Furthermore, the
application of these methodologies has allowed us to characterize the positions and amplitudes of multiple returns.
Hence, the approach can be used for characterization of distributed non-cooperative targets at kilometer ranges,
even in environments where low-light level and and/or eye-safe operation is necessary.
The technique has also been applied in conjunction with a rapid scanning approach, to acquire three-dimensional
information of a target scene with frame times of approximately 1 second.
Large-area low-jitter silicon single photon avalanche diodes
Author(s):
Massimo Ghioni;
Angelo Gulinatti;
Ivan Rech;
Piera Maccagnani;
Sergio Cova
Show Abstract
Single photon counting (SPC) and time correlated single photon counting (TCSPC) techniques have been developed in
the past four decades relying on photomultiplier tubes (PMT), but interesting alternatives are nowadays provided by
solid-state single photon detectors. In particular, silicon Single Photon Avalanche Diodes (SPAD) fabricated in planar
technology join the typical advantages of microelectronic devices (small size, ruggedness, low operating voltage and low
power dissipation, etc.) with remarkable basic performance, such as high photon detection efficiency over a broad
spectral range up to 1 μm wavelength, low dark count rate and photon timing jitter of a few tens of picoseconds. In
recent years detector modules employing planar SPAD devices with diameter up to 50 µm have become commercially
available. SPADs with larger active areas would greatly simplify the design of optical coupling systems, thus making
these devices more competitive in a broader range of applications. By exploiting an improved SPAD technology, we
have fabricated planar devices with diameter of 200 μm having low dark count rate (1500 c/s typical @ -25 °C). A
photon timing jitter of 35 ps FWHM is obtained at room temperature by using a special pulse pick-up network for
processing the avalanche current. The state-of-the-art of large-area SPADs will be reviewed and prospects of further
progress will be discussed pointing out the challenging issues that must be faced in the design and technology of SPAD
devices and associated quenching and timing circuits.
Single photon avalanche photodiodes for near-infrared photon counting
Author(s):
Mark A. Itzler;
Xudong Jiang;
Rafael Ben-Michael;
Bruce Nyman;
Krystyna Slomkowski
Show Abstract
InP-based single photon avalanche diodes (SPADs) have proven to be the most practical solution currently available
for many applications requiring high-performance photon counting at near-infrared wavelengths between 1.0 and 1.6
µm. We describe recent progress in the design, characterization, and modeling of InP-based SPADs, particularly with
respect to the dark count rate vs. photon detection efficiency metric of devices optimized for use at both 1.55 μm and
1.06 μm. In this context, we report for the first time dark count probabilities as low as 7 x 10-7 ns-1 for fiber-coupled
1.55 μm SPADs operated at 20% detection efficiency and 215 K. Additionally, because of the critical role played by
afterpulsing in limiting photon counting rates, we describe recent characterization of the dependence of afterpulsing
effects on SPAD operating conditions such as photon detection efficiency, repetition rate, and bias gate length.
A novel quenching circuit to reduce afterpulsing of single photon avalanche diodes
Author(s):
Mingguo Liu;
Chong Hu;
Joe C. Campbell;
Zhong Pan;
Mark M. Tashima
Show Abstract
In this paper, we report a new quenching circuit for single photon avalanche diodes, passive-quenching-with-activereset.
This circuit uses a large resistor to passively quench the avalanche current and a transistor to actively reset the
diode to the operating voltage after a specified hold-off time. Afterpulsing is reduced by minimizing the total charge
flow during avalanche, which can be achieved by minimizing the stray capacitance in the circuit. The simulation of the
circuit using PSpice showed that the circuit is operating correctly. The operation of the circuit was demonstrated using
discrete components. A quenching time of ~2ns and a dynamic range of ~100dB have been achieved. The performance
can be further improved by integrating the transistor with the photodiode to reduce the stray capacitance.