Discovery of high-temperature superconductors (HTSC)
and development of technology of their manufacturing in the
form of a thin film allow realizing sensitive microwave devices
of millimeter and sub-millimeter ranges of waves working at
the liquid-nitrogen level of temperature [1–5]. The study of
properties of usual superconductors and HTSC films under the
laser beam were carried out. Several technologies for their
manufacture in the form of films are developed which allows
realizing optically controlled sensors, switches as well as
mixers, delay lines, parametric amplifiers and other microwave
devices [6–12]. The study of properties of usual superconductors and HTSC films under the laser beam were carried
out. Several technologies for their manufacture in the form of
films are developed which allows realizing optically controlled
sensors, switches as well as mixers, delay lines, parametric
amplifiers and other microwave devices [6–12]. Nevertheless, it
is indicated in most of works [1–10] that the signal of the HTSC
photo-response contains a reply of non-bolometric nature. The
microscopic nature of interactions of optical radiation with
HTSC films on the non-bolometric case of excitation is not yet
fully understood; previous investigations spread light only on
some aspects of these interactions.
On the other hand, as it is shown by us early [6–9] that active
and reactive components of the surface microwave impedance
of HTSC thin films can be modulated under a ‘‘pump’’ law,
when an optical signal modulated on the intensity:
F ¼
F0
2
ð1 þ sin vstÞ;
incidents on the HTSC film, where F0 is the intensity of the
incident radiation; vs the frequency of the modulation; and t
time.
Let non-bolometric transfer of electrons through the
superconducting gap (the cooper pairs breaking) takes place
at the absorption of optical radiation by the HTSC film. Let full
concentration of electrons within the framework of two-liquid
model [1–12] is kept (n = ns + nN = nsF + nNF). Then, the
concentration of electrons in the superconducting condition ns
decreases and the concentration of normal electrons nN
increases by the same value DN. As a consequence, expressions
for the appropriate concentration of electrons at the irradiation
n
sF and nNF can be written down as