Partition Noise Research Articles

Improved time-resolved simulation of amplitude and phase fluctuations in semiconductor laser light

We present an algorithm designed to produce improved simulations of amplitude and phase fluctuations present in the light output of semiconductor lasers. The algorithm is based on the physical principle of operation of semiconductor lasers, and takes fully into account the correlation between amplitude and phase fluctuations, as well as partition noise at the laser output. The simulated results are shown to agree very well with theoretical, frequency-domain noise descriptions.

A Simple and Color-Free WDM-Passive Optical Network Using Spectrum-Sliced Fabry–PÉrot Laser Diodes

We propose and demonstrate a simple and color-free wavelength-division-multiplexing passive optical network (WDM-PON) using spectrum-sliced Fabry-Perot laser diodes (F-P LDs). Due to its low front facet reflectivity (~0.1%), the F-P LD shows a broadband lasing spectrum and reduced mode partition noise. By utilizing multiple peaks that are separated by the free-spectral range of the cyclic arrayed waveguide gratings, the 16-channel WDM-PON is successfully demonstrated at 155 Mb/s.

Effects of Fermi Liquid Interactions on the Shot Noise of anSU(N)Kondo Quantum Dot

We study shot noise in the current of quantum dots whose low-energy behavior corresponds to an SU(N) Kondo model, focusing on the case N=4 relevant to carbon nanotube dots. For general N, two-particle Fermi-liquid interactions have two distinct effects: they can enhance the noise via backscattering processes with an N-dependent effective charge, and can also modify the coherent partition noise already present without interactions. For N=4, in contrast with the SU(2) case, interactions enhance shot noise solely through an enhancement of partition noise. This leads to a nontrivial prediction for experiment.

An Electronic Dispersion Compensator (EDC) With an Analog Eye-Opening Monitor (EOM) for 1.25-Gb/s Gigabit Passive Optical Network (GPON) Upstream Links

Today, network systems require higher bandwidth for applications such as fiber-to-the-home communications. Gigabit passive optical network (GPON) links using a Fabry-Perot laser are attractive solutions for this high-speed network. However, due to the mode partition noise and fiber dispersion, GPON systems suffer from inter-symbol interference (ISI). In this paper, we present an electronic dispersion compensator (EDC) that will improve a 1.25-Gb/s experimental GPON link. The experimental GPON link is simulated and measured with impairment assessment. An analog eye-opening monitor, which captures the quality of the EDC output signal using the tunable delay and the integrator is proposed. The proposed EDC successfully compensates ISI for a given link with a 1.25-Gb/s signal. All circuits are fabricated using a 0.18mum- CMOS process.

A WDM-PON Employing Fabry–PÉrot Laser Diodes Without a Seed Light Injection

We propose and demonstrate a wavelength-division-multiplexed passive optical network by employing double-contact Fabry-Perot laser diodes (F-P LDs) without a seed light injection. To avoid the high mode partition noise at low frequency, we use a binary phase-shift keying as a modulation format at a low relative intensity noise window. An error-free transmission is achieved by compensating a lasing envelope shift due to temperature variation with the double-contact F-P LD.

Sex differences in plasma corticosterone release in undisturbed chickens ( Gallus gallus) in response to arginine vasotocin and corticotropin releasing hormone

In birds, two neuropeptides, corticotropin releasing hormone (CRH) and arginine vasotocin (AVT), are major regulators of the hypothalamo-pituitary-adrenal axis (HPA) during the stress response. In birds, however, the relative efficacy of CRH and AVT to stimulate the HPA axis in males and females remains unknown. The purpose of this study was to determine the time course of CORT release following central CRH and AVT administration to male and female chickens. Chickens were fitted with a stainless steel cannula surgically implanted in the lateral ventricle and a catheter chronically inserted in the jugular vein. Birds were housed individually in cages behind a one-way glass partition and unnecessary noise was avoided during the sampling period. Each bird received a single 5.0 μl intracerebroventricular (ICV) injection of either saline (SAL), AVT (10 and 100 pmol), or CRH (10 and 100 pmol). Blood was sampled remotely every 15 min for 2 h and plasma CORT was determined by radioimmunoassay. There was a significant increase in plasma CORT concentration in males injected with 100 pmol AVT beginning at 15 min post-injection through 2 h compared with SAL injected birds. In males, injection of 100 pmol CRH was significantly more effective in releasing CORT compared to an equal molar concentration of AVT or SAL. In females, ICV injection of 100 pmol AVT induced moderate increase in CORT levels. In contrast, 100 pmol CRH significantly increased plasma CORT compared to SAL injected controls but the CORT response was nearly 50% less than that obtained in males.

Bidirectional SCM Transmission Using a Noise-Suppressed Fabry–Pérot Laser Diode and a Reflective Semiconductor Optical Amplifier in a WDM/SCM-PON Link

We have proposed and experimentally demonstrated a bidirectional hybrid wavelength-division-multiplexed/subcarrier-multiplexed (SCM)-passive optical network based on a noise-suppressed Fabry-Peacuterot laser diode (FP-LD) and a reflective semiconductor optical amplifier (RSOA). For downlink data transmission, an FP-LD with multiple wavelength characteristics was used, and the mode partition noise of the FP-LD was reduced using a gain-saturated SOA with high-pass filter characteristics. For uplink data transmission, the downlink optical source was reused and remodulated by an SCM method, using an RSOA. A bidirectional SCM link with radio frequencies (RFs) of 2.4 GHz in the downlink and 1.0 GHz in the uplink was implemented. To confirm the validity of the proposed configuration, a 16-quadrature amplitude modulation transmission experiment was performed on a 10-km bidirectional optical access link. The transmission performance was investigated by means of the error vector magnitude and RF spectrum

Mode partition noise in 850 nm VCSELs

In high-speed 850 nm vertical cavity surface emitting lasers designed for 10 G Ethernet over 300 m of multimode fibre, mode partition noise (MPN) can impair the performance of the transmission link where the power budget is limited. A simple and practical method to evaluate the Ogawa k-factor from the power penalty is presented due to MPN using free space optical filters to vary the laser root mean square spectral width. k values that varied from 0.3 to 0.45 is reported. In addition, the previously reported improvement in power penalty is confirmed in the presence of polarisation mode selective filtering.

Multiwavelength modelocked semiconductor lasers for photonic access network applications

High performance, inexpensive light sources are needed for the advancement of wavelength division multiplexed (WDM) photonic access networks. In this paper, the unique features of multiwavelength modelocked semiconductor lasers are demonstrated with an emphasis on possible integration into access networks. An evaluation of multiwavelength passive, active, and hybrid modelocking reveals that hybrid modelocking is optimum for the suppression of mode partition noise as well as coherence tailoring in multiwavelength lasers. Low-distortion propagation of 10 channeltimes5 GHz multiwavelength pulses through multimode fiber is achieved. Intracavity gain flattening enables the simultaneous generation of 6 GHz pulse trains into 168 parallel wavelength channels for a 1 THz aggregate pulse rate from a single laser source. This work conveys the potential for semiconductor laser modelocking to produce multiple telecommunications wavelengths for data transmission and auxiliary functions in photonic networking

Simulations and Experiments on the Effective Optical Gain of FEC in a GPON Uplink

This letter studies the effective optical gain of Reed-Solomon (RS) forward-error correction (FEC) in a burst-mode gigabit passive optical network (GPON) uplink. Numerical simulations are made of the performance of an RS (255, 239) FEC code. For the first time, FEC performance is measured in a 1.25-Gb/s burst-mode GPON uplink in the presence of mode partition noise (MPN). Measurements show that the effective optical gain of RS (255, 239) can be considerably higher than 2.7 dB when MPN dominates

Performance analysis of a wavelength-locked Fabry-Perot laser diode by light injection of an external spectrally sliced Fabry-Perot laser diode

We have analyzed and experimentally demonstrated the performance of a wavelength-locked Fabry-Perot laser diode (FP-LD) with a spectrally sliced FP-LD as an external-injection optical source. A high side-mode suppression ratio exceeding 30 dB was obtained, and the noise characteristic of the wavelength-locked FP-LD was analyzed in terms of both mode partition noise and interferometric noise. The measured relative intensity noise had a minimum value of -140 dB/Hz. We also investigated the transmission characteristics such as the Q factor and extinction ratio for a 622 Mbits/s and 2.5 Gbits/s baseband digital signal.

Noise suppressed Fabry-Pe/spl acute/rot laser diode with gain-saturated semiconductor optical amplifier for hybrid WDM/SCM-PON link

We have proposed and experimentally demonstrated a novel optical source configuration for hybrid wavelength-division-multiplexing/subcarrier multiplexing (SCM) passive optical network using a gain-saturated semiconductor optical amplifier (GS-SOA) and a Fabry-Peacuterot laser diode (F-P LD). The mode partition noise of an F-P LD was suppressed by the frequency response characteristic of a GS-SOA. To confirm the validity of the proposed scheme, 16-quadrature amplitude modulation transmission experiment was performed in 20.4-km optical access link for three SCM frequency groups (0.8, 1.5, and 2.4 GHz). The error vector magnitude less than 4% was successfully obtained in the transmission experiment

Shot noise and spin-orbit coherent control of entangled and spin-polarized electrons

We extend our previous work on shot noise for entangled and spin polarized electrons in a beam-splitter geometry with spin-orbit (\textit{s-o}) interaction in one of the incoming leads (lead 1). Besides accounting for both the Dresselhaus and the Rashba spin-orbit terms, we present general formulas for the shot noise of singlet and triplets states derived within the scattering approach. We determine the full scattering matrix of the system for the case of leads with \textit{two} orbital channels coupled via weak \textit{s-o} interactions inducing channel anticrossings. We show that this interband coupling coherently transfers electrons between the channels and gives rise to an additional modulation angle -- dependent on both the Rashba and Dresselhaus interaction strengths -- which allows for further independent coherent control of the electrons traversing the incoming leads. We derive explicit shot noise formulas for a variety of correlated pairs (e.g., Bell states) and lead spin polarizations. Interestingly, the singlet and \textit{each} of the triplets defined along the quantization axis perpendicular to lead 1 (with the local \textit{s-o} interaction) and in the plane of the beam splitter display distinctive shot noise for injection energies near the channel anticrossings; hence, one can tell apart all the triplets, in addition to the singlet, through noise measurements. We also find that spin-orbit induced backscattering within lead 1 reduces the visibility of the noise oscillations, due to the additional partition noise in this lead. Finally, we consider injection of two-particle wavepackets into leads with multiple discrete states and find that two-particle entanglement can still be observed via noise bunching and antibunching.

Reset and Partition Noise in Active Pixel Image Sensors

Partition noise appears in conjunction with reset noise at the integration node of active pixel sensor architectures. This brief presents the modeling and measurement of partition noise based on an improved technique for charge profile estimation in the transistor channel at any given time instant. Transistor turn off transients are integrated into the model by taking into account both drift and diffusion components of current. Using the predictions of charge profile, partition noise generated during the transistor reset operation is accurately determined and verified with measured data.

Optimisation of remote seeding optical source in wavelength-locked FP-LD bidirectional WDM access optical link

The optimised characteristics of a wavelength-locked Fabry-Perot laser diode (FP-LD) have been analysed and demonstrated experimentally using remote seeding continuous wave (CW) optical source at central office (CO). The important issues of mode partition noise (MPN) of an FP-LD and Rayleigh backscattering arising from the same wavelength bidirectional transmission are investigated. The Q factor, sidemode suppression ratio (SMSR), and power penalty of a wavelength-locked FP-LD against signal-to-backscattering-power ratio (SBR) were measured. They can be optimised for the SBR range between 22 dB and 31 dB. From the measurements, both the MPN and Rayleigh backscattering can be controlled well owing to remote seeding of an FP-LD and hence use feasibly a wavelength-locked FP-LD in a wavelength division multiplexing-passive optical network (WDM-PON) optical link.

Characterizing relative intensity noise in InGaAsP-InP triangular ring lasers

This paper discusses relative intensity noise (RIN) characterization of triangular ring lasers, fabricated through a self-aligned dry etching process in InGaAsP-InP. Unusual low frequency noise enhancement was observed in each of the output beams, that is strongly dependent on the mirror backscattering strength. We explain the physical origin of the unusual RIN results as a partition noise effect between the two output beams of the ring laser, which can be best interpreted as superposition of two incoherent spatially bidirectional modes, generated by incoherent spontaneous emission photons traveling in clockwise and counterclockwise directions. This effect is unique to the ring laser geometry, and reported here for the first time. General noise predictions of our analysis are consistent with experimental measurements. This partition noise enhancement is expected to be present in the entire class of bidirectional semiconductor ring lasers, affecting the noise performance of not only the triangular ring laser, but also circular and square geometries, and possibly microdisk type lasers, in integrated photonic circuit applications.

Linewidth and relative intensity noise measurements of longitudinal modes in ultrahigh-speed mode-locked laser diodes

The longitudinal linewidth and corresponding relative intensity noise (RIN) of 10- and 40-GHz mode-locked laser diodes are measured for the first time to our knowledge. It is shown that the cavity Q value is a dominant parameter of the linewidth. It is also shown that the linewidth of the individual modes is almost constant. This means that the phase noise of each mode is almost the same in the mode-locked condition. The RIN value is larger for modes that are distant from the center longitudinal mode. This mode dependence is a consequence of the mode partition noise.

Effect of interactions on the noise of chiral Luttinger liquid systems

We analyze the current noise, generated at a quantum point contact in fractional quantum Hall edge state devices, using the chiral Luttinger liquid model with an impurity and the associated exact field theoretic solution. We demonstrate that an experimentally relevant regime of parameters exists where the noise coincides with the partition noise of independent Laughlin quasiparticles. However, outside of this regime, this independent particle picture breaks down and the inclusion of interaction effects is essential to understand the shot noise.

Effects of dephasing on shot noise in an electronic Mach-Zehnder interferometer

We present a theoretical study of the influence of dephasing on shot noise in an electronic Mach-Zehnder interferometer. In contrast to phenomenological approaches, we employ a microscopic model where dephasing is induced by the fluctuations of a classical potential. This enables us to treat the influence of the environment's fluctuation spectrum on the shot noise. We compare against the results obtained from a simple classical model of incoherent transport, as well as those derived from the phenomenological dephasing terminal approach, arguing that the latter runs into a problem when applied to shot noise calculations for interferometer geometries. From our model, we find two different limiting regimes: If the fluctuations are slow as compared to the time-scales set by voltage and temperature, the usual partition noise expression T(1-T) is averaged over the fluctuating phase difference. For the case of ``fast'' fluctuations, it is replaced by a more complicated expression involving an average over transmission amplitudes. The full current noise also contains other contributions, and we provide a general formula, as well as explicit expressions and plots for specific examples.

Reset noise in active pixel image sensors

In most image sensor pixel architectures, signal detection involves the reset of charge in a capacitive node. This operation gives rise to reset noise, and in particular, partition noise. In modern day transistors, with the shrinkage of device critical dimensions and increase of clock frequency, reset noise impacts many aspects of active pixel sensor operation. An additional spurious noise component has been observed from the reset noise model that is closely related to the switching operation, and is known as partition noise. Partition noise has been found to relate closely to the fall times of the applied reset pulse. However, existing noise models assume a constant charge density at the onset of transistor pinch-off, thus resulting in an underestimation of partition noise. This work investigates the influence of reset noise and other related noise generation on active pixel sensor performance.