Page 56 - ITU Journal Future and evolving technologies – Volume 2 (2021), Issue 2

ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 2

BPFD BPFD BPFD TP
TONE LOSS=1 dB LOSS=1.5 dB SUBCKT LOSS=1 dB ID=TP1
FRQ=4.25 GHz SUBCKT FP1=8 GHz SUBCKT FP1=16.5 GHz LIN_S NET="System Diagram 4" FP1=30 GHz SUBCKT
PWR=8 dBm NET="System Diagram 2" FP2=9 GHz NET="System Diagram 3" FP2=17.5 GHz NET="HMC5805ALS6" FP2=40 GHz NET="System Diagram 5"
1 2 1 2 1 2 1 2
8 dBm 4 dBm 8 dBm 15 dBm

Fig. 5 – AWRDE setup of MWE approach-based frequency multiplier
M_PROBE
ID=VP1
SUBCKT
PORTFN NET="EA1"
P=1
1 2 M_PROBE M_PROBE SUBCKT SUBCKT
ID=VP2 ID=VP3 SUBCKT
2 SUBCKT ID=S6 ID=S6 ID=S12
NET="PD1" NET="EA2-1" NET="EA2-2" NET="RF BPF"
M_PROBE
3 1 2 1 2 1 2 ID=VP4
ISOL8R
ISOL=100 dB
PORTFN SUBCKT SPLIT2 1 SUBCKT
P=2 NET="Laser" NET="MZM1"
2
1 2 1
M_PROBE M_PROBE M_PROBE SUBCKT
3 ID=VP5 ID=VP6 SUBCKT ID=VP7 COAXRWG_TE10 SUBCKT ID=S9
2 SUBCKT SUBCKT ID=S4 ID=WG1 ID=S8
NET="OBGF" NET="OA" NET="PD2" NET="EA3" NET="WG-BPF"
ISOL8R 3 1 2 1 2 1 2
ISOL=100 dB
PORT
P=3
1 SUBCKT
NET="MZM2"
Fig. 7 – AWRDE setup of MWP approach-based frequency multiplier
Currently, the operating principles and features of of dividing coefficients of both splitters, and ideal
the above optoelectronic devices are described in a linear electro-optic effect, the transfer function of
large number of publications (see, for example, MZM will correspond to formula (1), where V is
[15]). Nevertheless, for a better understanding, we applied voltage, Vπ is a so-called half-wave voltage
believe it necessary to explain the operation of the related to control bias at which the phase
Mach-Zehnder electro-optic intensity modulator in difference in the two MZI arms reaches 180º.
the modes of MATB and MITB used in this model.
The basic circuit of MZM, is shown in Fig. 8. 1   V  

V
T MZM ( ) = 2  1 + cos  0 +   (1)
RF input MT   V   
RF CPW
φ1 Calculated by (1) taking into account the data in
Optical input a b I Table 3, the transfer characteristic of the MZM with
1-a 1-b the marked areas of MATB and MITB modes is
Optical output
φ2 shown in Fig. 9.
single-mode
optical RF CPW
waveguide
RF input MT

Fig. 8 – Basic circuit of MZMs used in MWP approach-based
frequency multiplier
In the figure unmodulated laser emission is
introduced through the input optical waveguide. In
accordance with the principle of designing a
widely-known Mach-Zehner interferometer (MZI),
the optical circuit contains two planar single-mode
waveguides formed in lithium niobate connected
by input and output Y-couplers with branching
coefficients “a” and “b”. Depending on the phase
difference between optical fields, φ1- φ2, the light
can constructively or destructively interfere. An Fig. 9 – The transfer characteristic of the MZM
interaction with propagating an optical signal is 4.3 Simulation results
performed by the coplanar waveguides (CPW)
including the matched terminations (MT) on their In the course of the simulation experiment, first,
ends. Assuming no loss in waveguides, the equality the spectra at the output of the frequency
multiplier for the circuits in Fig. 3 and Fig. 4 were

42 © International Telecommunication Union, 2021