Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An optical all-pass filter realized by using self-compensation of loss   Filters are key devices in optical systems and are usually applied to signal
suppression or selection based on their amplitude frequency responses.
Different from amplitude filtering, an all-pass filter (APF) is a unique type
of filter that exhibits a uniform amplitude and variable phase in the frequency
response. Traditionally, an APF is designed to be ideal and lossless, which is
impossible in practice. Here we demonstrate a method of realizing an APF even
when transmission loss exists, and a possible structure for realizing the lossy
APF is proposed. The method indicates that a lossy APF can be realized by
introducing self-compensation of loss to the structure of an ideal single-stage
APF, and an APF based on silicon-on-insulator (SOI) foundry is fabricated and
demonstrated. The method of self-compensation of loss can also be used to
realize APFs in the electrical domain. We anticipate that our work will inspire
realizations of more APF-related devices that once seemed impossible in
practice.

26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ