Ultra-narrow (sub-MHz) linewidth emission from discrete mode laser diodes

A class of laser which exhibits ultra-narrow sub MHz linewidth emission necessary for numerous applications in optical communications and sensors is described. The spectral performance of commercial discrete mode (DM) and distributed feedback (DFB) lasers is compared. The devices used in this work are asymmetrically coated ridge waveguide Fabry Perot lasers which incorporated etched slot features and emitting around lambda = 1.55 mum. The active region of the devices consisted of a strained compensated InAlGaAs MQW structure

Low sensitivity to optical feedback and optical injection of discrete mode lasers

In this paper, we demonstrate the low sensitivity to both external optical feedback and external optical injection of a new type of extremely low cost single-mode lasers, called "discrete mode" (DM) lasers. The DM lasers are obtained from ridge waveguide Fabry Perot (FP) lasers, in which the effective refractive index of the lasing mode has been perturbed. These lasers exhibit a low sensitivity to external optical feedback since the coherence collapse threshold is around 5 dB higher in comparison to a commercial DFB laser

1-(Thio­phen-2-yl)ethanone thio­semi­carbazone

The title compound, C7H9N3S2, crystallizes with two unique mol­ecules in the unit cell, both present as thio­semicarbazide tautomers. The mol­ecules differ principally in the dihedral angles between the thio­phene ring planes and the planes through the non-H atoms of the hydrazinecarbothio­amide units, viz. 9.80 (8)° for one mol­ecule and 19.37 (7)° for the other. The hydrazinecarbothio­amide units are reasonably planar, with r.m.s. deviations of 0.001Å for each of the mol­ecules. In the crystal, N—H⋯S hydrogen bonds link like mol­ecules into R 2 2(8) inversion dimers. A three-dimensional network structure is generated by additional N—H⋯S hydrogen bonds and weak C—H⋯S contacts between the unique mol­ecules

Anti-CD45RC antibody immunotherapy prevents and treats experimental autoimmune polyendocrinopathy-candidiasis- ectodermal dystrophy syndrome

Targeted monoclonal antibody (mAb) therapies show great promise for the treatment of transplant rejection and autoimmune diseases by inducing more specific immunomodulatory effects than broadly immunosuppressive drugs routinely used. We recently described the therapeutic advantage of targeting CD45RC, expressed at high levels by conventional T (Tconv) cells (CD45RC(hi)), their precursors, and terminally differentiated T (TEMRA) cells, but not by regulatory T cells (Tregs; CD45RC(lo/-)). We demonstrated efficacy of anti-CD45RC mAb treatment in transplantation, but its potential has not been examined in autoimmune diseases. Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare genetic syndrome caused by loss-of-function mutations of autoimmune regulator (AIRE), a key central tolerance mediator, leading to abnormal autoreactive T cell responses and autoantibody production. Herein, we show that, in a rat model of APECED syndrome, anti-CD45RC mAb was effective for both prevention and treatment of autoimmune manifestations and inhibited autoantibody development. Anti-CD45RC mAb intervention depleted CD45RC(hi) T cells, inhibited CD45RC(hi) B cells, and restored the Treg/Tconv cell ratio and the altered Treg transcriptomic profile. In APECED patients, CD45RC was significantly increased in peripheral blood T cells, and lesioned organs from APECED patients were infiltrated by CD45RC(hi) cells. Our observations highlight the potential role for CD45RC(hi) cells in the pathogenesis of experimental and human APECED syndrome and the potential of anti-CD45RC antibody treatment.Peer reviewe

Experimental Injection Map of Semiconductor Laser Submitted to Filtered Feedback

International audienceOptical injection consists in the unidirectional coupling between a "slave" laser (SL) and a "Master" laser (ML). The injected SL may exhibit different behaviors, showing frequency locking, wave mixing, relaxation regimes, period doubling, and chaos. The different regimes may be mapped on a chart where the injected power and the detuning between the slave and the master frequencies are varied. In this paper, a detailed overview of the regimes are given when the SL is submitted to both optical injection and filtered optical feedback. This last coupling is realized thanks to an extended cavity, which includes a frequency filter. When the SL is operating far from threshold (4 Ith), typical regimes mentioned for feedback-free laser are observed for all the external-cavity modes. On the contrary, when the SL operates close to threshold (1.5 Ith), it is shown that the dynamics is wealthier. New regimes, as one for which simultaneously chaos and locking occur, can be identified, in comparison to the case of a single-frequency SL

Injection map of semiconductor laser submitted to filtered feedback

session 6 « Nonlinear dynamics of semiconductor lasers II », http://www.metz.supelec.fr/phase

Robustness of synchronization of two semiconductor lasers: comparison between optical injection by a continuous or a chaotic wave

EQEC topic EC " Dynamics, Instabilities and Patterns ", oral session 6 " Synchronization and feedback " [EC6-5-THU]International audienceSynchronization of chaotic signals is studied when the chaos is generated through optical injection avoiding optical feedback. The use of optical injection enables a strict comparison when a continuous or a chaotic wave seeds the laser

Synchronization map of two uni-directionally coupled chaotic semiconductor lasers

mini-symposia MS 18 " Lasers Dynamics ", session 3 " VCSELs and Coupled lasers " [18-427]International audienc

Pulse and SYstem CHAracterization of MOde-Locked Laser for Optical Communications

diffusion restreinteRapport Final contrat Ulyss

Comparaison de la synchronisation d'un laser à semi-conducteurs par l'injection optique d'un signal chaotique ou continu

International audienceL'injection optique consiste en un couplage unidirectionnel d'un laser dit maître avec un laser esclave. Le laser injectée présente une large variété de comportement dynamique : accrochage en fréquence, mélange d'ondes, doublement de période, chaos, relaxation, bistabilité. Ce même procédé est utilisé pour synchroniser un laser avec un laser ayant un comportement chaotique. Le chaos est généré par contre-réaction optique et il est important d'atteindre des hyper-chaos (chaos de haute dimension) dans le cas d'applications liées à la cryptographie. Le laser esclave peut quant à lui être ou non soumis µa contre-réaction optique. La synchronisation est souvent comparée au comportement du laser soumis µa injection optique. Si quelques travaux théoriques existent sur la robustesse de la synchronisation et la comparaison avec l'injection optique par un signal continu, nous n'avons pas connaissance de travaux expérimentaux sur ce type de comparaison. Nous avons récemment proposé l'étude d'une synchronisation s'affranchissant de toute contre-réaction optique. Si l'expérience proposée est basée sur un chaos de faible dimension, elle présente l'avantage de pouvoir faire varier les paramµetres de contrôle, de permettre une comparaison directe avec le cas de l'injection d'un signal continu et d'être interprétée par un modèle simple. Nous montrons que la synchronisation s'effectue sur les zones de mélange d'onde déterminées dans le cas de l'injection optique par un signal continu et qu'il existe une valeur seuil de la puissance injectée permettant d'obtenir une corrélation satisfaisante entre les deux signaux