Abstract:
Wavelength Division Multiplexing (WDM) is a very attractive option to satisfy the rapidly
growing bandwidth needs. Multiplexing devices made it possible to exploit the real bandwidth
of optical fibre. An optical switch is a key device while performing the reconfigurable
multiplexing operations. Several number of wavelength switches have been demonstrated
which are based on various approaches. Mach-Zehnder interferometer based structure is
considered as efficient due to its characteristics, such as: low crosstalk, low insertion loss, and
fabrication simplicity.
We have designed an optimal two channels tuneable wavelength switch based on Mach-
Zehnder interferometer (MZI). The material used for the fabrication of the device is a
compressive strained multiple quantum well (MQW) grown to a silicon doped InP wafer. We
have analysed the waveguide and multimode interference (MMI) coupler to be used in our
device. Two MMI couplers of ~100 μm length and 4.5 μm of width have been used in our
design due to their high bandwidth, low loss, and low crosstalk characteristics. A 400 μm long
active phase-shifter is set in one of the two arms of MZI for the phase shift function as well as
wavelength tuning. Wavelength tuning is obtained by injecting the DC biased current in the
phase-shift region. The device analysis, on the basis of bandwidth and crosstalk, was performed
by using Beam Propagation Method (BPM). A FWHM bandwidth of about 390 nm is achieved
at the central wavelength 1550 nm. The transmission loss is recorded as low as 24 dB while a
crosstalk of -38 dB has to be discovered in our solutions.
