Polarisation insensitive wavelength de‐multiplexer using arrayed waveguide grating and polarisation rotator/splitter

Abstract

The authors report the polarisation insensitive operation of an arrayed waveguide grating using a polarisation rotator/splitter (PRS) waveguide device which attains identical wavelength characteristics and optical losses for both transverse electric (TE) and transverse magnetic (TM) polarisations. The proposed PRS device is composed of a rib structure waveguide and an asymmetrical directional coupler (ADC). The rib waveguide converts TM fundamental mode to TE first-order mode. The ADC splits TE first-order mode into the TE fundamental mode propagating in the sub-adjacent waveguide. Experimental results confirm that the proposed device operates independently of light polarisations; channel isolation is nearly 20 dB, and no transmission wavelength shift or polarisation dependent loss are observed between TE and TM polarisations.

Polarization Diversified 16λ Demultiplexer Based on Silicon Wire Delayed Interferometers and Arrayed Waveguide Gratings

“…Based on the cascaded connection of multistage delayed interferometers with different path lengths and optical splitting ratios [8], [9], the DMZI region was designed to have flat-topped spectral response with an extremely low excess loss. As it was already reported in previous works [14], [19], by using the counter-propagating type AWG, we can make the entire scheme much smaller and simpler. Since the AWG does not need to increase N Ch , and the DMZI interleaver intrinsically has much less insertion loss [9] than AWG type interleaver [20], the proposed device configuration has great advantages in terms of low loss and design simplicity.…”

“…Mach-Zehnder interferometers (DMZIs) [9]- [12] and arrayed waveguide grating (AWG) [13], [14]. To make WDM transmission capability much better, we need to further increase the channel count (N Ch ) of MUX/DeMUX.…”

“…Additionally, as it has been well known that since a polarization state of a signal is not maintained when the signal is transmitted through single mode fibers (SMFs), the DeMUX located at a receiver side is normally needed to operate for arbitrarily polarized input signal [14], [19]. In order to cope with this situation, by utilizing polarization diversity scheme, we also verify 16λ demultiplexing together with 32 Gbps modulated non-return-to-zero (NRZ) signal transmission for orthogonally polarized inputs in C-band range.…”

Polarization Splitter-Rotator Based on Multimode Waveguide Grating

“…It should be noted that all the reported PSRs are designed for broadband operation, aiming as universal schemes for realizing polarization-transparent photonic integrated circuits (PICs). However, for some critical applications such as polarization insensitive wavelength division (de)multiplexer [23,24], wavelength selective devices such as arrayed waveguide gratings (AWGs) are subsequently required to implement wavelength multiplexing [25], inevitably incurring extra insertion loss and footprint and design complexity to the whole on-chip system. Exploiting novel polarization conversion mechanisms and developing new functional devices are desirable for PICs application.…”

“…The proposed PSR boasts a high extinction ratio, low crosstalk, an easy fabrication process, and great design flexibility. Additionally, such a device can be further cascaded with grating assisted contra-directional couplers (contra-DCs) [35,36], paving the way for critical applications such as polarization insensitive wavelength division (de)multiplexer [23,24] and multichannel polarization-multiplexed differential quadrature phase-shift keying (PM-DQPSK) transceiver [37,38].…”