Y. Gottesman

Institut Mines-Télécom | telecom-sudparis.eu · EPH : Electronique et Physique

The diagnosis of many diseases relies, at least on first intention, on an analysis of blood smears acquired with a microscope. However, image quality is often insufficient for the automation of such processing. A promising improvement concerns the acquisition of enriched information on samples. In particular, Quantitative Phase Imaging (QPI) techni...

Two-dimensional observation of biological samples at hundreds of nanometers resolution or even below is of high interest for many sensitive medical applications. Recent advances have been obtained over the last ten years with computational imaging. Among them, Fourier Ptychographic Microscopy is of particular interest because of its important super...

Digital pathology based on a whole slide imaging system is about to permit a major breakthrough in automated diagnosis for rapid and highly sensitive disease detection. High-resolution FPM (Fourier ptychographic microscopy) slide scanners delivering rich information on biological samples are becoming available. They allow new effective data exploit...

Digital pathology based on whole slide imaging system is about to permit major breakthrough in automated diagnosis for a rapid and highly sensitive disease detection. High-resolution FPM (Fourier Ptychographic Microscopy) slide scanners delivering rich information on biological samples are becoming available. They allow new effective data exploitat...

Digital pathology based on whole slide imaging system is about to permit major breakthrough in automated diagnosis for a rapid and highly sensitive disease detection. High-resolution FPM (Fourier Ptychographic Microscopy) slide scanners delivering rich information on the sample such as intensity and its complementary phase image are becoming availa...

2D observation of biological samples at hundreds of nanometers resolution or even below is of high-interest for many sensitive medical applications. Recent advances have been obtained with computational imaging and we consider here Fourier Ptychographic Microscopy (FPM). Although this technique has permitted to attain an impressive super-resolution...

2D observation of biological samples at hundreds of nanometers resolution or even below is of high-interest for many sensitive medical applications. Recent advances have been obtained with computational imaging and we consider here Fourier Ptychographic Microscopy (FPM). Although this technique has permitted to attain an impressive super-resolution...

Digital pathology based on whole slide imaging system is about to permit major breakthrough in automated diagnosis for a rapid and highly sensitive disease detection. High-resolution FPM (Fourier Ptychographic Microscopy) slide scanners delivering rich information on the sample such as intensity and its complementary phase image are becoming availa...

Digital pathology based on whole slide imaging system is about to permit major breakthrough in automated diagnosis for a rapid and highly sensitive disease detection. High-resolution FPM (Fourier Ptychographic Microscopy) slide scanners delivering rich information on the sample such as intensity and its complementary phase image are becoming availa...

Polarization light microscopy is a very popular approach for structural imaging in optics. So far these methods mainly probe the sample at a fixed angle of illumination. They are consequently only sensitive to the polarization properties along the microscope optical axis. This paper presents a novel method to resolve angularly the polarization prop...

Nous proposons un nouveau capteur optique biométrique 3D hautement sécurisé basé sur la Tomographie par cohérence optique (ou OCT), permettant de mesurer finement les caractéristiques propres au doigt analysé.

We propose a very fast heterodyne technique to recover the amplitude and phase of short optical pulses generated e.g. by a mode-locked laser. A linearly swept frequency source is used to scan the entire optical spectrum of the mode-locked laser in a single continuous sweep. The beat signal is recorded on a fast oscilloscope and then digitally proce...

Device characterization of Quantum-Dash semiconductor mode-locked laser using a continuous tuning swept source is presented. This technique is linear, simple and does not require any prior information about the signal under test.

The future technology migration in access networks compels the development of key innovative transmitters operating at 10 Gb/s around 1550 nm and capable of transmitting data in extended reach passive optical networks (>60 km). A laser modulated directly appears to be a low cost and a simple solution to address these needs. However, the extinction...

A graded-index multi-mode fiber has been optimized to sustain a single excited mode when coupled with a standard single-mode fiber at 1310/1550nm while offering large effective modal bandwidth at 850nm under VCSEL excitations. Modeling and experimental results are presented.

The capability of measuring the spectral and temporal phase of an optical signal is of fundamental importance for the advanced characterization of photonic and optoelectronic components, biochemical sensors, structural monitoring sensors and distributed sensor networks. To address this problem, several techniques have been developed (frequency-reso...

In the present work, we report on the spectral and temporal phase measurement capabilities of OFDR. Precise characterization of spectral phase information is demonstrated by retrieving the phase response of a commercial optical filter, the Finisar Waveshaper 1000 S/X programmable in attenuation and phase over C+L band (1530-1625 nm). Additionally,...

In order to achieve indoor positioning, and hence a real continuity of the positioning service in all environments, we designed a new pseudolite-based system using the so-called repealites. A single GNSS-like signal is transmitted from all the repealites (typically 4 for 3D positioning): this approach simplifies both the synchronization process (be...

In order to achieve indoor positioning, and hence a real continuity of the positioning service in all environments, we proposed a new pseudolite-based system: the repealites. A single GNSS-like signal is transmitted from all the repealites (typically 4 for 3D positioning): this approach simplifies both the synchronization process (between transmitt...

Dispositif permettant d'obtenir une image tomographique en optique cohérente. Ce dispositif permet de faire des cartographie spectrale et spatiale des objets sous test avec une sensibilité importante (-120dB) et une résolution spectrale de quelques pm.

We propose and demonstrate a new modified Lyot filter to independently ensure the channel amplitude equalization and the bandwidth tuning functions. The device consists of hybrid liquid crystal interferometers. We show numerically and experimentally that for a modified four-stage Lyot filter, the two first interferometers ensure equalization functi...

We propose and demonstrate a novel optical imple- mentation to simultaneously improve the contrast and increase the finesse of a classical -stage Lyot filter. The new device based on the multiple-passage concept uses two mirrors placed at the ex- tremities of the filter. The light beam passes through the structure back and forth and each passage ha...

One of the most important functionality in any optical network is the filtering function. High performances devices dedicated to this function are desirable, especially for DWDM (Dense wavelength Division Multiplexing) configurations. The optical filters must be adapted to the high density spectrum, and so, have a high contrast (over 40dB) and a Fu...

The paper presents experimental validations of a new approach of GNSS indoor positioning. Combining the best of pseudolites [1] and repeaters [2], the new “repealite” technique allows carrier phase measurements (in order to improve positioning accuracy and multipath mitigation) and self synchronised transmissions. Thus, this method greatly simplifi...

We propose and demonstrate here the high efficiency of concurrent time and frequency analysis to detect and unambiguously identify the coupled cavities in real photonic crystals containing imperfections and/or process-induced disorder. This procedure when applied to reflectograms recorded using phase-sensitive optical low-coherence reflectometry al...

An alternative method of ring resonators (RRs) spectral analysis is proposed and demonstrated here. Unlike earlier procedures, the phase information is extracted here from pure spectral intensity data to examine the RR signatures in the time domain. This procedure gives a direct access to all resonator parameters. Also, it is well suited for an aut...

We investigate the impact of disorder on the prop-agation of photonic crystal waveguide modes using phase-sensi-tive optical low-coherence reflectometry. Combined with a suit-able numerical processing, this technique reveals a considerable amount of information that we cast as time-wavelength reflectance maps. By comparing measurements on different...

Disorder induced scattering is crucial for understanding slow light in Photonic Crystal. We investigate dispersion and scattering losses on PhC structures with tailored dispersion and discuss their potential for delay control and all-optical switching.

Disorder induced scattering is crucial for understanding slow light in Photonic Crystal. We investigate dispersion and scattering losses on PhC structures with tailored dispersion and discuss their potential for delay control and all-optical switching.

Our new 3DBR-MMI-SOA covers 41nm tuning with only one simultaneous Bragg current, and is compatible with fast switching. Its short cavity and simple tuning mechanism provide large technological tolerances, simple control, and high industrial yield.

In this paper, we propose and demonstrate an original exploitation of relaxation oscillations of erbium-doped-fiber laser ring resonators based on a general model for Er cross-sectional characterization. Its main advantage as compared to other existing exploitations relies on the fact that only weak approximations relative to spatial light distribu...

We propose a solution to improve gain-clamped EDFA stabilization time by inserting in the conventional laser loop configuration an extra SOA. Experimental results demonstrate stabilization time as short as 0.2¿s in a purposely-considered critical situation.

We demonstrate that in addition to their role in tuning the wavelength of an N-stage hybrid liquid-crystal Šolc filter, liquid-crystal cells can also be used to vary the transmission bandwidth of such filter around any of the tuned wavelength. This bandwidth tuning is based on the variation of the number of stages by what we call here an “optical c...

An electro-optically tunable erbium-doped fiber ring laser with a side mode suppression ratio of ~ 51.2 dB and a 0.062 nm linewidth is demonstrated. Wavelength tuning is achieved with a hybrid liquid crystal Solc structure used as an intracavity tunable filter. The laser wavelength is tuned over 28.6 nm with a tuning rate of 2.38 nm/V.

This paper describes a simple methodology implying the use of optical low-coherence reflectometry and its associated simulations to detect and spatially localize defects in Bragg grating based emission devices such as a phase-shifted DFB laser and a DBR laser with an involuntarily introduced defect in the grating

Photonic crystal waveguides, fabricated on InP substrate using an inductively coupled plasma etching process, show propagation losses of 40dB/mm with one missing row and of less than 10 dB/mm with three missing rows.

This paper describes the efficient implementation of optical low-coherence reflectometry (OLCR) measurements to evaluate the performance of InP-based high-index contrast ring resonators. Using examples of racetrack ring resonators, this paper shows here for the first time that all characteristic parameters relevant to resonator design (coupling coe...

The high potential of optical low-coherence reflectometry to investigate the failure mode of InP-based optical devices is demonstrated here by considering two examples of burned (under high optical output power and operating temperature) distributed Bragg reflector lasers on InP. In addition to monitoring reflections in the conventional reflection...

Describes the high potential of optical low-coherence reflectometry (OLCR) and its upgraded in-situ facilities to assess the fabrication techniques of InP-based photonic circuits and also to help to optimize the design and further evaluate the performance of several key components (butt-joints, bend guides, MMI couplers, EAMs, DBR lasers, etc.,).

This letter describes a judicious implication of optical low-coherence reflectometry (OLCR) measurements to evaluate the principal characteristics of an electroabsorption modulator with passive sections on either ends of its active layer fabricated on an InP substrate. We show here that careful monitoring of the reflections at the transition region...

This paper draws attention to the basic principles governing reflections in uniform Bragg reflectors (BR) when measured employing optical low coherence reflectometry (OLCR) technique. Using computations based on transfer matrix method (TMM), we first showed a strong spectral dependence of Bragg reflectograms on an OLCR probe spectrum. Later, this d...

The main problem of integrated laser/Mach-Zehnder modulators is the modulated feedback due to reflections on the output multimode image (MMI). We have solved this problem changing the modulator technology from "deep-ridge" to "shallow-ridge" technology. In that case, the index step seen by the light in the MMI is far lower, then reflections which a...

We report here on the high potential of low-coherence reflectometry, a basically nondestructive technique, to detect and to localize spatially the degradation damaged regions in ∼1.3 μm laser diodes on InP. Using ∼1.3 μm low-coherence probe, three Fabry–Perot lasers with identical active regions (compressively strained multi-quantum wells) and exhi...

Summary form only given. The high complexity of present photonic integration technologies on InP necessitates a thorough knowledge of the prominence of reflections in guiding layers as they can profoundly influence the circuit performance. These can originate at spatially localized refractive index discontinuities in the guide and can have several...

This paper describes a comprehensive report on the high potential of optical low-coherence reflectometry (OLCR) measurements to assist the design optimization and performance evaluation of symmetric MMI couplers. Using three sets of deep-ridge InGaAsP–InP couplers on InP and by performing OLCR measurements simultaneously in reflection and transmiss...

A high precision reflectometer for probing of localized reflections in photonic devices and circuits on InP was described. The reflectometer employed was the Michelson interferometer equipped with two low-coherence light probes. The optical and opto-electronic quality of the cavity were investigated through the transmitted probe light and the edge-...

Describes a simple and efficient means of evaluating the performance of deep-ridge dual-order mode couplers, a key component in all-optical Mach-Zehnder wavelength converters. The principal characteristics of these couplers namely, the optimal operation wavelength range and the corresponding mode rejection ratio have been determined for the first t...

We propose and demonstrate here the high efficiency of a novel design for deep-ridge multimode interference (MMI) couplers rendering them to behave like good transmitters with minimized reflections when integrated with emission devices. Using optical low-coherence reflectometry measurements, this novel design is shown to suppress to a great extent...

The broadband source of a high-precision optical low-coherence reflectometer is simultaneously employed in conventional reflection and transmission modes to monitor the internal properties of multimode imaging (MMI) devices. Using two carefully chosen examples, we show that this new methodology should permit precise assessment of the performance of...

We demonstrate here that hydrogenation offers a simple and attractive solution to fabricate low-loss InGaAsP/InP photonic integrated circuits operating at 1.56 μm. Using InGaAsP/InP buried waveguide test structures closely imitating the passive sections of photonic circuits, we first demonstrate that hydrogenation helps to bring down significantly...

The Zn and Be doped (1 to 2×10¹⁸ cm^-3) p-InP samples are first hydrogenated by exposing to a deuterium (D) plasma to passivate (or neutralize) acceptors through dopant-H interactions. Later on, subsequent to 10 min isochronal anneals up to 450°C, the reactivation of holes is monitored to determine activation energies, ~0.7 eV...

We show here that the high propagation losses often measured at /spl sim/1.56 /spl mu/m in InGaAsP-InP buried-ridge stripe waveguides can be significantly brought down by implementing hydrogenation (exposure to deuterium plasma) as the last step to device termination. For example, losses as high as /spl sim/30 dB/cm measured in conventional as-proc...