Granin - Derived Peptides in the Eye

The granins are the acidic proteins of secretory granules and there exist three main members of this family, in particular chromogranin A, chromogranin B and secretogranin II. These proteins are widely distributed throughout neuroendocrine tissues and are stored in large dense core vesicles in neuronal cells. Their functional role is not fully clear but it seems that they might play an important role in the formation of secretory granules. Furthermore, the primary amino acid sequence of the granins features many pairs of basic amino acids and these pairs together with monobasic residues are targets of enzymes which proteolytically process the proteins, in particular the prohormone convertases 1 and 2. Thus the granins might be precursors of smaller fragments and they are indeed cleaved

Generation of Arbitrary Frequency Chirps with a Fiber-Based Phase Modulator and Self-Injection-Locked Diode Laser

We present a novel technique for producing pulses of laser light whose frequency is arbitrarily chirped. The output from a diode laser is sent through a fiber-optical delay line containing a fiber-based electro-optical phase modulator. Upon emerging from the fiber, the phase-modulated pulse is used to injection-lock the laser and the process is repeated. Large phase modulations are realized by multiple passes through the loop while the high optical power is maintained by self-injection-locking after each pass. Arbitrary chirps are produced by driving the modulator with an arbitrary waveform generator

2-laser injection-locking configuration for Brillouin fibre sensors

We propose in this paper a novel method for generating the pump and probe signals for a Brillouin fibre sensor. It is based on the injection locking of two distinct semiconductor lasers, that makes possible the generation of high purity beat signals in the microwave frequency range. Such a technique can be used either in the pulsed pump-probe technique or the new correlation-based technique. Furthermore novel devices, such as laser modules presenting integrated electro-absorption modulators, can be exploited for achieving efficient and cost effective injection locking scheme

Novel measurement scheme for injection-locking experiments

A novel experimental setup for injection-locking experiments is presented. The single-mode-fiber-based configuration allows one to precisely control the power and the polarization state of the light injected from the master laser into the slave laser cavity. Different behaviors typical for injection locking with single-mode semiconductor lasers (e.g., stable injection locking, undamped relaxation oscillations, nearly degenerate four-wave mixing, period doubling, chaotic behavior) are experimentally observed and theoretically verified using a rate-equation-based model. Measurements and calculations are entirely linked analytically and thoroughly compared by means of the corresponding power spectra. The good quantitative agreement between measurements and model validates the model, the analytical approach, and the experimental setu

Novel schemes for optical signal generation using laser injection locking with application to Brillouin sensing

Injection locking of two DFB semiconductors opens new possibilities to generate effective signals for optical sensing, in order to reach better performances. Pure wave forms can be generated with qualities exceeding those obtained using external modulators. This is illustrated through the application to the distributed Brillouin sensing that shows significant progress with respect to established techniques. © 2004 IOP Publishing Ltd

Generation of high-quality signals for optical sensing using DFB lasers injection locking

Injection locking of two DFB semiconductors opens new possibilities to generate effective signals for optical sensing, in order to reach better performances. Pure waveforms can be generated with qualities exceeding those obtained using external modulators

Novel measurement scheme for injection locking experiments with semiconductor lasers

A novel measurement scheme is presented for injection locking experiments with semiconductor lasers. In the method, the light generated by the master laser travels through an optical fiber before being injected into the cavity of the slave laser. Using the reciprocity principle, it is possible to control accurately the absolute light power injected from the master laser in the cavity of the slave laser once the power coupling coefficient between the slave waveguide mode and the fiber mode is determined. In addition, the polarization can be fully controlled despite the birefringence of the optical fiber. The scheme may be easily adapted for experiments with passive optical feedback

High order amplitude equation for steps on creep curve

We consider a model proposed by one of the authors for a type of plastic instability found in creep experiments which reproduces a number of experimentally observed features. The model consists of three coupled non-linear differential equations describing the evolution of three types of dislocations. The transition to the instability has been shown to be via Hopf bifurcation leading to limit cycle solutions with respect to physically relevant drive parameters. Here we use reductive perturbative method to extract an amplitude equation of up to seventh order to obtain an approximate analytic expression for the order parameter. The analysis also enables us to obtain the bifurcation (phase) diagram of the instability. We find that while supercritical bifurcation dominates the major part of the instability region, subcritical bifurcation gradually takes over at one end of the region. These results are compared with the known experimental results. Approximate analytic expressions for the limit cycles for different types of bifurcations are shown to agree with their corresponding numerical solutions of the equations describing the model. The analysis also shows that high order nonlinearities are important in the problem. This approach further allows us to map the theoretical parameters to the experimentally observed macroscopic quantities.Comment: LaTex file and eps figures; Communicated to Phys. Rev.