We report the first experimental observation of three distinct forms of two-wavelength switching (clockwise, anticlockwise, and butterfly) for a 1550 nm vertical cavity surface emitting laser (VCSEL) operated just above threshold and subject to orthogonally polarized optical injection. The spectrum of the device exhibits two modes, a main mode emitting in a "parallel'' polarization and a subsidiary "`orthogonal'' polarized mode. Low input-power switching of the emission wavelength of the VCSEL by an orthogonally polarized external optical signal injected to the long-wavelength side of the subsidiary mode is observed. Clockwise switching and bistability of the main lasing mode with very high on-off contrast ratio has been measured in all cases. Three different switching shapes: anticlockwise, butterfly, and clockwise, have been measured for the output of the optically injected VCSEL. This diversity of switching behavior with a 1550 nm VCSEL subject to optical injection offers promise for the use of these devices in all-optical switching/routing as well as optical interconnect applications.

Two-Wavelength Switching With a 1550 nm VCSEL Under Single Orthogonal Optical Injection

SPIE's International Symposium on Optical Science, Engineering, and Instrumentation報告

Preparation of electro-optical active liquid crystal microdomains by the sol-gel process

The characteristics of optical bistability in a vertical-cavity semiconductor optical amplifier (VCSOA) operated in reflection are reported. The dependences of the optical bistability in VCSOAs on the initial phase detuning and on the applied bias current are analyzed. The optical bistability is also studied for different numbers of superimposed periods in the top distributed bragg reflector (DBR) that conform the internal cavity of the device. The appearance of the X-bistable and the clockwise bistable loops is predicted theoretically in a VCSOA operated in reflection for the first time, to the best of our knowledge. Moreover, it is also predicted that the control of the VCSOA's top reflectivity by the addition of new superimposed periods in its top DBR reduces by one order of magnitude the input power needed for the assessment of the X- and the clockwise bistable loop, compared to that required in in-plane semiconductor optical amplifiers. These results, added to the ease of fabricating two-dimensional arrays of this kind of device could be useful for the development of new optical logic or optical signal regeneration devices.

/pdf/modeling-reflective-bistability-in-vertical-cavity-cj3xgeq7uu.pdf

Modeling reflective bistability in vertical-cavity semiconductor optical amplifiers

We have measured optical power and wavelength polarization bistability in a 1550nm-Vertical Cavity Surface-Emitting Laser (VCSEL) subject to orthogonally-polarized optical injection into the orthogonal polarization of the fundamental transverse mode. Optical bistability with very wide hysteresis cycles, up to four times wider than previously reported results has been measured for both the optical power and wavelength domain. We also report the experimental observation of three different shapes of polarization bistability, anticlockwise, clockwise and X-Shape bistability, all of them with wide hysteresis cycles. This rich variety of behaviour at the important wavelength of 1550 nm offers promise for the use of VCSELs for all-optical signal processing and optical switching/routing applications.

Power and wavelength polarization bistability with very wide hysteresis cycles in a 1550nm-VCSEL subject to orthogonal optical injection

Digital chaotic behavior in an optically processing element is reported. It is obtained as the result of processing two fixed trains of bits. The process is performed with an optically programmable logic gate, previously reported as a possible main block for optical computing. Outputs for some specific conditions of the circuit are given. Digital chaos is obtained using a feedback configuration. Period doublings in a Feigenbaum‐like scenario are obtained. A new method to characterize this type of digital chaos is reported.

http://oa.upm.es/21610/1/Digital_chaotic_output_from_an_optically_processing_element.pdf

Digital chaotic output from an optically processing element

Switching of a signal beam by another control beam at different wavelength is demonstrated experimentally using the optical bistability occurring in a 1.55 /spl mu/m-distributed feedback semiconductor optical amplifier (DFBSOA) working in reflection. Counterclockwise (S-shaped) and reverse (clockwise) bistability are observed in the output of the control and the signal beam respectively, as the power of the input control signal is increased. With this technique an optical signal can be set in either of the optical input wavelengths by appropriate choice of the powers of the input signals. The switching properties of the DFBSOA are studied experimentally as the applied bias current is increased from below to above threshold and for different levels of optical power in the signal beam and different wavelength detunings between both input signals. Higher on-off extinction ratios, wider bistable loops and lower input power requirements for switching are obtained when the DFBSOA is operated slightly above its threshold value.

/pdf/two-wavelength-switching-with-a-distributed-feedback-50a8rfs9jm.pdf

Two-wavelength switching with a distributed-feedback semiconductor optical amplifier (DFBSOA)

A new methodology to study irregular behaviours in logic cells is reported. It is based on two types of diagrams, namely phase and working diagrams. Sets of four bits are grouped and represented by their hexadecimal equivalent. Some hexadecimal numbers correspond to certain logic functions. The influence of the internal and external tolerances, namely those appearing in the employed devices and in the working signals, may be analysed with this method. Its importance in the case of logic structures with chaotic behaviours is studied.

/pdf/analysis-of-irregular-behaviour-on-an-optical-computing-3nmv3z55ti.pdf

Analysis of irregular behaviour on an optical computing logic cell

A new method to analyze the influence of possible hysteresis cycles in devices employed for optical computing architectures is reported. A simple full adder structure is taken as the basis for this method. Single units, called optical programmable logic cells, previously reported by the authors, compose this structure. These cells employ, as basic devices, on-off and SEED-like components. Their hysteresis cycles have been modeled by numerical analysis. The influence of the different characteristic cycles is studied with respect to the obtained possible errors at the output. Two different approaches have been adopted. The first one shows the change in the arithmetic result output with respect to the different values and positions of the hysteresis cycle. The second one offers a similar result, but in a polar diagram where the total behavior of the system is better analyzed.

/pdf/method-to-analyze-the-influence-of-hysteresis-in-optical-rl978nuine.pdf

Jose Antonio Martin-Pereda

Papers

Modeling reflective bistability in vertical-cavity semiconductor optical amplifiers

Digital chaotic output from an optically processing element

Two-wavelength switching with a distributed-feedback semiconductor optical amplifier (DFBSOA)

Analysis of irregular behaviour on an optical computing logic cell

Method to analyze the influence of hysteresis in optical arithmetic units