InP-based polarisation independent wavelength demultiplexers

5.2 Polarisation dispersion compensation 87
processing, this method appeals to the controllability of the production process and to the skills
of the persons who actually manufacture the devices.
InP layer thickness [nm]
400
350
300
250
Table 5.1 Design parameters of the demultiplexer.
-4.0
-3.6
-3.2
-2.8
-2.4
-2.0
-1.6
-0.4
0.0
1.2
2.0
2.4
2.8
3.6
4.0
4.4
0.8
1.6
3.2
4.8
-1.2
-0.8
0.4
Parameter Value
centre wavelength λ c
1534 nm
number of channels N 8
channel spacing Δλ ch (Δf ch ) 3.2 nm (400 GHz)
array order m 37
free spectral range Δλ FSR
number of array waveguides N a
41.5 nm
62
array length 1.6 mm
array height 1.1 mm
TE-TM shift Δλ pol
4.0 nm
correction length δL 12.48 μm
centre wavelength shift Δλ c
index contrast ΔN
index contrast Δn
200
500 550 600 650 700
Q(1.3) layer thickness [nm]
-2.0
-1.6
-0.4
0.0
1.2
2.0
2.4
2.8
3.6
4.0
4.4
-1.2
-0.8
0.4
0.8
1.6
3.2
4.8
Etch depth into Q(1.3) layer [nm]
200
180
160
140
120
100
7.4 nm
– 9.8 10 3 –
⋅
– 2.3 10 2 –
⋅
(a) (b)
80
60
40
20
1.2
1.6
2.0
2.4
3.0
3.2
2.8
2.2
1.8
1.4
1.6 1.8 2.0 2.2 2.4
Waveguide width [μm]
Figure 5.5 TE-TM shift (nm) as a function of the guiding layer and the cladding
layer thickness (a) and as a function of waveguide width and etch depth into the
guiding layer (b).
0.4
0.8
2.6
1.0
-0.2
0.6
-0.4
0.2
-0.6
0.0
0.4
0.8
-0.8
1.0
-0.2
-0.4
0.6
-1.0
-0.6
0.0
0.2