We present squeezing and anti-squeezing spectra of the output from a degenerate optical parametric oscillator (OPO) network arranged in different coherent quantum feedback configurations. One OPO serves as a quantum plant, the other as a quantum controller. The addition of coherent feedback enables shaping of the output squeezing spectrum of the plant, and is found to be capable of pushing the ...

An efficient locking technique based on optical feedback is demonstrated to suppress jitter on the rf beat note between the two modes of a dual-frequency Yb:Er glass laser. The method consists of a self-injection process in which one selected mode serves as a master oscillator to lock and stabilize the second mode via a frequency-shifted optical feedback. The beat note adjusted near 170 MHz was...

We present a photon noise and diffraction-limited imaging method combining an imaging laser and ultrasonic waves. The laser optical feedback imaging (LOFI) technique is an ultrasensitive imaging method for imaging objects through or embedded within a scattering medium. However, LOFI performances are dramatically limited by parasitic optical feedback occurring in the experimental setup. In this ...

NONLINEAR EQUALIZATION BASED ON DECISION FEEDBACK EQUALIZER FOR OPTICAL COMMUNICATION SYSTEM by Xiaoqi Han Nonlinear impairments in optical communication systems have become the major performance limiting factor of optical communication systems. The equalizer based on linear filters has limited compensation capability. Therefore, nonlinear models based equalizers are proposed for performance en...

abstract the extent to which teachers’ written corrective feedback (wcf) is conducive to esl learners’ improvement has been discussed since truscott’s claim in 1996. the mentioned debate continues because there has been lots of contrastive research studies with different results. this paper presents the results of a 2-month study of the effectiveness of wcf to 65 low intermediate iranian learne...

We show theoretically through computer simulations that phase-conjugate optical feedback that is realized through four-wave mixing can produce mode locking in multilongitudinal-mode semiconductor lasers. Phase-conjugate feedback, in contrast to ordinary optical feedback, directly couples pairs of longitudinal modes. For certain strengths of phase-conjugate reflectivities, the phases and beat fr...

We demonstrate the influence of vectorial coupling on the synchronization behavior of complex systems. We study two semiconductor lasers subject to delayed optical feedback which are unidirectionally coherently coupled via their optical fields. Our experimental and numerical results demonstrate a characteristic synchronization scenario in dependence on the relative feedback phase leading cyclic...

The experience from years of development and use, the advance of technology, and the development of authoring tools for questions and tests has resulted in a sophisticated, computer based assessment system. However, there is still a lot of room for further development. Some of the current ideas for development are discussed in the remainder of this work. A primary aim of assessment, both format...

We demonstrate experimentally all-optical stabilization of a single-mode laser diode subject to external optical feedback operating in the low-frequency fluctuations (LFF) regime, by the technique of applying a second delayed optical feedback. We interpret our results as suppression of LFF through destruction of the antimodes responsible for the LFF crises and stabilization of the laser through...

Many dissipative optical systems support patterns. Dissipative solitons are generally found where a pattern coexists with a stable unpatterned state. We consider such phenomena in driven optical cavities containing a nonlinear medium (cavity solitons) and rather similar phenomena (feedback solitons) where a driven nonlinear optical medium is in front of a single feedback mirror. The history, th...