Fabrication of a microresonator-fiber assembly maintaining a high-quality factor by CO2 laser welding

We demonstrate fabrication of a microtoroid resonator of a high-quality (high-Q) factor using femtosecond laser three-dimensional (3D) micromachining. A fiber taper is reliably assembled to the microtoroid using CO2 laser welding. Specifically, we achieve a high Q-factor of 2.12*10^6 in the microresonator-fiber assembly by optimizing the contact position between the fiber taper and the microtoroid.Comment: 7 pages, 5 figure

The Status Quo, Characteristics and Challenges of Vocational Education Development in Kenya Under the Background of International Aid

Since independence, the political situation in Kenya has gradually stabilized and the economy has developed rapidly. With the government's increasing emphasis on education, vocational education has received unprecedented attention as an important driving force for national economic transformation. Under the influence of international environment and national economic development and industrial level, the development of vocational education in Kenya is divided into three stages: the period of professional development of secondary education in the early 60s and early 1980s; the adjustment and depression of vocational education policy in the late 1980s and 1990s. During that period and this century, the development of vocational education in Kenya has been promoted along with the Millennium Development Goals. Driven by a series of policies issued by the Kenyan government, the development of vocational education has made remarkable progress. By analyzing the professional cooperation between Kenya and international organizations and other countries, the characteristics and challenges of vocational education in Kenya are summarized. Keywords: Vocational Education; Kenya; Characteristics ; Challenges ;International Ai

Observation of non-Hermitian corner states in non-reciprocal topolectrical circuits

Exploring topological phases in non-Hermitian systems has attracted significant recent attention. One intriguing question is how topological edge states compete with the non-Hermitian skin effect. Here, we report the experimental observation of corner states in a two-dimensional non-reciprocal rhombus honeycomb electric circuit. The system is non-reciprocal and non-Hermitian because the introduced capacitance between two nodes depends on the current direction. The current-inversion negative impedance converters (INIC) is employed to realize the non-reciprocal coupling in circuit. Skin effect thus emerges due to the non-reciprocity and prevails in dragging the corner state into the bulk. The non-Bloch winding number defined in generalized Brillouin zone is adopted to characterize the topological phase transition. Interestingly, we find that the non-Bloch Z2 Berry phase can serve as an invariant to describe the non-Hermitian topology. By tuning the non-reciprocal parameter, we observe unbalanced distribution of corner states emerging on two acute angles of the rhombus lattice, with the localization length of the left corner state increasing exponentially with the degree of non-reciprocity.Comment: 8 pages, 7 figure