An Er"+-doped fiber ring laser with unidirectional operation without optical isolator has been investigated for different cavity conditions. The fiber ring laser cavity is built in such a way that the optical fields propagating in the two directions suffer different losses. As a consequence, the laser oscillation appears in a quasi-unidirectional form. By incorporating a fiber pigtailed bandpas...

We show that a ring is a Krull ring if and only if every nonzero regular prime ideal contains a t-invertible prime ideal if and only if every proper regular principal ideal is quasi-equal to a product of prime ideals.

In the title compound, C(19)H(22)N(4)O(2), the tetra-hydro-pyrimidine ring adopts an envelope conformation (with the N atom connected to the benzyl group representing the flap). This benzyl group occupies a quasi-axial position. The two benzyl groups lie over the tetra-hydro-pyridimidine ring. The amino group is a hydrogen-bond donor to the nitro group.

The paper studies some properties of the ring of integer-valued quasi-polynomials. On this ring, theory of generalized Euclidean division and generalized greatest common divisor are presented. Applications to finite simple continued fraction expansion of rational numbers and Smith normal form of integral matrices with an integer parameter are also given.

In this paper is considered the preservation of properties of the ring of coefficients R to the rings R[x] and R [[x]], where R[x] denotes the polynomials ring and R [[x]] is the power series ring. This study is carry out in the context of finite conductor rings; in particular, properties like GCD, G − GCD, coherence, quasi coherence and finite conductor are analized.

‎in this paper we give a characterization of unmixed tripartite‎ ‎graphs under certain conditions which is a generalization of a‎ ‎result of villarreal on bipartite graphs‎. ‎for bipartite graphs two‎ ‎different characterizations were given by ravindra and villarreal‎. ‎we show that these two characterizations imply each other‎.

This work analyses theoretically, technologically and practically a class of low-loss single-mode optical fibers with ring refractive index profile. The fibers are considered for long distance signal transmission as well as photonic signal processing. Trunk transmission, ring index fibers have shifted and flattened dispersion characteristics and much larger effective area as compared with stand...