Abstract
A numerical simulation on absorptive bi-stability and resonance wavelength shift is carried out in a vertical-cavity semiconductor saturable absorber consisting of a Fabry–Perot cavity embedded with quantum-wells (QWs) material with due consideration of its nonlinear index change and thermal effects. Necessary equations are derived and discussions are made for optimization of cavity parameters required for all-optical logic operations. For InGaAs/InP quantum wells, the resonant wavelength is blue-shifted by
4
nm and red-shifted by
16
nm for input intensities of
0.15
I
S
and
2.2
I
S
, respectively where
I
S
represents the saturation intensity. Faithful NAND operation with extinction over
85% is possible for a signal intensity change (Δ
I
in
) of
0.5I
S
in a sample with saturated nonlinear index (
n
2S
) of
0.0012, unit small-signal absorption (
α
0
d) and non-saturable absorption (
α
ns
d) of
0.025. Whereas, the NOR operation is obtained with extinction over
80% for Δ
I
in
=
1.0I
S
in a sample with
n
2S
=
0.0012
,
α
0
d
=
1.0
and
α
ns
d
=
0.0375
, respectively.
► Reflective vertical cavity semiconductor saturable absorber is numerically investigated for logic operation. ► Nonlinear index change and thermal effects are considered. ► Extinctions over 85% for NAND and 80% for NOR are possible with usual parameter values. ► Simulated results support experimental observations reported elsewhere.