A Four-Channel DWDM Tunable Add/Drop Demultiplexer Based on Silicon Waveguide Bragg Gratings

Abstract

We demonstrate a thermally tunable four-channel add/drop demultiplexer based on silicon grating-assisted contra-directional couplers (contra-DCs) for 200 GHz dense wavelength division multiplexing (DWDM) systems. In order to obtain the narrow bandwidth and the rapid roll-off necessary for the DWDM, every wavelength channel is filtered dually by two identical contra-DCs cascaded in parallel. In addition, the phase apodization technique is utilized to suppress sidelobes. With these special designs, passbands of the four drop ports exhibit 3 and 20 dB bandwidths of 0.4 and 0.8 nm, respectively, while isolation between adjacent channels is better than 20 dB. Insertion losses at through and drop ports are 0.6 and ∼2.6 dB, respectively. The maximal wavelength-tunable range is up to 25 nm.

Silicon-on-Insulator Microwave Photonic Filter With Widely Tunable and Reconfigurable Flat-Top Bandpass Functionality

“…5(b), illustrating that a BW value of 7.2 and 9.4 GHz is observed when the passband central frequency is spaced away from the the stopband center (i.e., the Bragg wavelength), by about 2 and 2.4 nm, respectively. Finally, by applying a tuning signal to the LH control electrode, the central frequency of the reconfigured bandpass transfer function can be changed over ranges as wide as few nanometers [35], [36], [37], allowing for separate control of the filter BW and central wavelength. As an example, the observed DFBR transmission spectra when the passband window is tuned in the middle of the stopband at two different voltage signal levels applied to the the top metal LH, for a wavelength shift of the fixed-bandwidth passabnad of ∼1.8 nm, is shown in Fig.…”

Electro-optic tunable grating-assisted optical waveguide directional coupler in lithium niobate

“…To solve this phase mismatch issue, it is suggested to introduce a grating into the ADC to compensate the phase mismatch between the two modes so as to achieve e cient mode coupling [2]. According to the grating type and the propagation direction of the coupled modes, GADC can be divided into Bragg grating assisted contra-directional couplers [3][4][5][6][7][8][9][10][11][12][13][14][15][16] and long period gratings (LPG) assisted codirectional couplers [17][18][19][20][21][22][23][24].…”

Using Periodic Trapezoidal Ag Strips and Silicon Dioxide Slab for Polarization-Independent Narrowband Absorber

“…Gratings are widely used in many fields due to their special periodic structure. [1][2][3] With its unique characteristics of beam splitting, polarization, dispersion, absorption, and phase matching, gratings occupy an important position in optical communications, [4,5] wavelength division multiplexing, [6][7][8][9] photoelectric sensors, [10][11][12][13][14] liquid crystal displays, [15][16][17] and optical signal acquisition and processing. [18][19][20] The absorber can achieve single-band and multi-band absorption with different structural designs.…”

“…Fig 8. The influences of silicon dioxide layer thickness h s on the absorption performances for the (a) TE and (b) TM polarization.…”