Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermoelectrically cooled THz quantum cascade laser operating up to 210
  K   We present a \MF{terahertz} quantum cascade laser operating on a
thermoelectric cooler up to a record-high temperature of 210.5 K. The active
region design is based on only two quantum wells and achieves high temperature
operation thanks to a systematic optimization by means of a nonequilibrium
Green's function model. Laser spectra were measured with a room temperature
detector, making the whole setup cryogenic free. At low temperatures ($\sim 40
K), a maximum output power of 200 mW was measured.

26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th