Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unidirectional Lasing Emerging from Frozen Light in Non-Reciprocal
  Cavities   We introduce a class of unidirectional lasing modes associated with the
frozen mode regime of non-reciprocal slow-wave structures. Such asymmetric
modes can only exist in cavities with broken time-reversal and space inversion
symmetries. Their lasing frequency coincides with a spectral stationary
inflection point of the underlying passive structure and is virtually
independent of its size. These unidirectional lasers can be indispensable
components of photonic integrated circuitry.

24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math