Pis’ma v ZhETF, vol. 109, iss. 2, pp. 82 - 84
© 2019
January 25
Waveguiding in all-garnet heteroepitaxial magneto-optical
photonic crystals
A. M. Grishin+∗1), S. I. Khartsev+
+KTH Royal Institute of Technology, SE-164 40 Stockholm-Kista, Sweden
∗Petrozavodsk State University, 185910 Petrozavodsk, Karelian Republic, Russia
Submitted 15 November 2018
Resubmitted 15 November 2018
Accepted 21
November 2018
DOI: 10.1134/S0370274X19020024
Over the past two decades materials with forbidden
A series of heteroepitaxial [BIG/SGG]m MOPCs
photonic band have formed a rapidly expanding niche of
have been fabricated by RF-magnetron sputtering of
photonics. They demonstrated great potential for light
composite 3Bi2O3 + 5Fe2O3 oxide and stoichiometric
guiding, filtering, and switching, exceptional dispersion
Sm3Ga5O12 (SGG) targets on single crystal Ca, Mg,
properties and promise integration with Complemen-
Zr :Gd3Ga5O12(111) substrates [9]. In both mirrors,
tary metal-oxide-semiconductor (CMOS) devices on Si
thickness of layers of Bragg reflectors was chosen to be
platform. Magnetic photonic band gap materials attract
equal a quarter of wavelength λres/4nBIG(SGG) in the
special interest since they possess nonreciprocal prop-
respective material, whereas the BIG in the optical res-
erties thus can serve as optical isolators (e.g., [1] and
onance cavity has a thickness λ/2nBIG. Refractive in-
references therein).
dices of BIG and SGG at the designed λres = 750 nm
M. Inoue et al. fabricated and tested the first
equal to nBIG = 2.679 and nSGG = 1.960.
1D magneto-optical (MO) photonic crystals (MOPCs)
Figure presents optical spectra of transmission T and
with Ta2O5/SiO2 dielectric mirrors and various MO-
FR angle ΘF for TM- and TE-polarized light incident at
materials for the central optical cavity: polycrystalline
an angle φ on 750-[BIG/SGG]5 MOPC with five pairs of
Bi-substituted dysprosium and yttrium iron garnets as
BIG/SGG reflectors. The oblique geometry removes the
well as granular Co-Sm-O and Fe-Si-O magnetic lay-
degeneracy of TE and TM polarizations that occurred
ers [2].
at normal incidence (φ = 0). All the resonant features
Significant breakthrough has been achieved using
as edges of the band gap and resonant central peaks
completely substituted bismuth iron garnet Bi3Fe5O12
experience signi-cant about 60 nm “blueshift” when the
(BIG) as a Faraday rotator with a record Faraday
incidence angle φ increases up to 70◦.
rotation (FR) ΘF = -8.4 deg/µm at 633 nm [3-5]. The
TM and TE polarizations behave differently: res-
first all-garnet 1D heteroepitaxial pulsed laser deposited
onant peak of TM-mode transmission has a constant
Bi3Fe5O12/Y3Fe5O12 MOPC at designed wavelength of
height whereas an intensity of transmitted TE-polarized
750 nm showed 140 % increased of FR compared with a
light rapidly decreases. Faraday rotation acts in an op-
single layer BIG of equivalent thickness [6]. Finally, the
posite way: a height of resonant peak of FR falls down
cutting edge results on MO properties were achieved in
with an angle φ increase for TM- and exceedingly grows
radio frequency (RF)-sputtered latching-type lumines-
for TE-polarized light.
cent
[Bi2.97Er0.03Fe4Al0.5Ga0.5Fe5O12/Sm3Ga5O12]m
Comparison of T and ΘF spectra for transmitted and
MOPCs. To the date, at λres
= 775(640)nm, FR
reflected light concludes that TM-mode exhibits twice
ΘF
=
-14.1(14.8)deg/µm represents the highest
stronger reflectivity within the stop band and signifi-
achieved MO performance. Compared to a single layer
cantly higher resonant transparency than TE-polarized
BIG film, specific FR ΘF was increased by the factor of
light.
12 [7,8].
The angular dependence of the resonance wave-
In this paper we present results on MO effects in
length λres(φ) has universal character for both the TM
transmission and FR of TM- and TE-polarized incident
and TE polarizations and nicely fits to the formula that
light that make evident resonant TE-mode waveguiding
expresses the condition of constructive light interfer-
within a MOPC cavity.
ence in the crystal with an effective refractive index neff:
λ(φ) = λ(0)[1 - (sin φ/neff)2]1/2.
The following observations testify the resonant TE-
1)e-mail: grishin@kth.se
mode waveguiding within a MOPC cavity:
82
Письма в ЖЭТФ том 109 вып. 1 - 2
2019
