Experimental demonstration and analysis of compact silicon-nanowire-based couplers

Compact 2 x 2 couplers based on silicon nanowires are fabricated and tested. They include a directional (X) coupler, a cross-gap coupler (CGC), and a multimode interference (MMI) coupler. The length of the X coupler\u27s parallel film waveguide is 1 μm. The theoretical minimum excess loss of the X coupler is 0.73 dB, whereas its experimental value is 1.0817 dB. CGC has a coupling region length of 24 μm. The minimum excess loss of CGC, which is 0.6 dB in theory, is experimentally determined to be 0.6737 dB. Taper waveguides are used as input/output waveguides for the MMI coupler. The footprint of the MMI region is only 6 x 57 μm2. The excess loss of the MMI coupler is theoretically 0.46 dB, but its experimental value is 0.5423 dB. The experimental nonuniformity of the MMI coupler is 0.0063 dB when the center wavelength is 1.55 μm. The maximum excess loss of the MMI coupler is 0.8233 dB in the wavelength range of 1.52 to 1.58 μm. The simulated and experimental results show that a small 2 x 2 MMI coupler that is suitable for optoelectronic integration exhibits lower excess loss, wider bandwidth, and better uniformity

Practical fabrication and analysis of an optimized compact eight-channel silicon arrayed-waveguide grating

We have designed, fabricated, and characterized a 1 x 8 ultrasmall compact arrayed-waveguide grating (AWG) on silicon-on-insulator (SOI) in a fiber grating demodulation integration microsystem. The miniature AWG, consisting of Si photonic wire waveguides, was designed using the complete modeling simulation in the beam propagation method. The device was fabricated on an SOI substrate and evaluated in the wavelength range around 1.55 μm, with an effective area of 230 x 160 μm. Clear demultiplexing characteristics were observed with a channel spacing of 1.91 nm. The influence of the waveguide widths on crosstalk defined by adjacent channel crosstalk and phase error is discussed. Insertion loss, crosstalk, and nonuniformity of loss were measured to be −3.18, −23.1, and −1.35 dB, respectively. Thus, the AWG design is the best choice for a fiber Bragg grating demodulation microsystem

Experimental demonstration and analysis of compact silicon-nanowire-based couplers

Compact 2 x 2 couplers based on silicon nanowires are fabricated and tested. They include a directional (X) coupler, a cross-gap coupler (CGC), and a multimode interference (MMI) coupler. The length of the X coupler\u27s parallel film waveguide is 1 μm. The theoretical minimum excess loss of the X coupler is 0.73 dB, whereas its experimental value is 1.0817 dB. CGC has a coupling region length of 24 μm. The minimum excess loss of CGC, which is 0.6 dB in theory, is experimentally determined to be 0.6737 dB. Taper waveguides are used as input/output waveguides for the MMI coupler. The footprint of the MMI region is only 6 x 57 μm2. The excess loss of the MMI coupler is theoretically 0.46 dB, but its experimental value is 0.5423 dB. The experimental nonuniformity of the MMI coupler is 0.0063 dB when the center wavelength is 1.55 μm. The maximum excess loss of the MMI coupler is 0.8233 dB in the wavelength range of 1.52 to 1.58 μm. The simulated and experimental results show that a small 2 x 2 MMI coupler that is suitable for optoelectronic integration exhibits lower excess loss, wider bandwidth, and better uniformity

Practical fabrication and analysis of an optimized compact eight-channel silicon arrayed-waveguide grating

We have designed, fabricated, and characterized a 1 x 8 ultrasmall compact arrayed-waveguide grating (AWG) on silicon-on-insulator (SOI) in a fiber grating demodulation integration microsystem. The miniature AWG, consisting of Si photonic wire waveguides, was designed using the complete modeling simulation in the beam propagation method. The device was fabricated on an SOI substrate and evaluated in the wavelength range around 1.55 μm, with an effective area of 230 x 160 μm. Clear demultiplexing characteristics were observed with a channel spacing of 1.91 nm. The influence of the waveguide widths on crosstalk defined by adjacent channel crosstalk and phase error is discussed. Insertion loss, crosstalk, and nonuniformity of loss were measured to be −3.18, −23.1, and −1.35 dB, respectively. Thus, the AWG design is the best choice for a fiber Bragg grating demodulation microsystem

Design optimization and comparative analysis of silicon-nanowire-based couplers

Three kinds of highly compact 2 x 2 couplers based on silicon nanowire are designed and optimized for the array waveguide grating (AWG) demodulation integration microsystem in this paper. These couplers are directional (X) coupler, cross gap coupler (CGC), and multimode interface (MMI) coupler. The couplers are simulated using the beam propagation method. The distance between the input/output waveguides is set to 10 μm considering the test of a single device in the following work. The total footprint of X coupler is 10 μmx 300 μm. The length of parallel film waveguide is 1 μm. After optimization, the minimum excess loss is 0.73 dB. CGC has a footprint of 10 μm x 300 μm , a coupling region length of 24 μm, and a minimum excess loss of 0.6 dB. Taper waveguides are used as input/output waveguides for MMI coupler. The footprint of MMI region is only 6 μm x 57 μm. The excess loss is 0.46 dB after optimization. Uniformity is 0.06 dB with transverse electric polarization when the center wavelength is 1.55 μm. The maximum excess loss is 1.55 dB in the range of 1.49 μm to 1.59 μm. The simulation results show that a small 2 x 2 MMI coupler exhibits lower excess loss, wider bandwidth, and better uniformity than X coupler and CGC. MMI coupler is suitable for the requirements of optoelectronic integration. 2012 IEEE

Optimal design of an ultrasmall SOI-based 1 x 8 flat-top AWG by using an MMI

Four methods based on a multimode interference (MMI) structure are optimally designed to flatten the spectral response of silicon-on-insulator- (SOI-) based arrayed-waveguide grating (AWG) applied in a demodulation integration microsystem. In the design for each method, SOI is selected as the material, the beam propagation method is used, and the performances (including the 3 dB passband width, the crosstalk, and the insertion loss) of the flat-top AWG are studied. Moreover, the output spectrum responses of AWGs with or without a flattened structure are compared. The results show that low insertion loss, crosstalk, and a flat and efficient spectral response are simultaneously achieved for each kind of structure. By comparing the four designs, the design that combines a tapered MMI with tapered input/output waveguides, which has not been previously reported, was shown to yield better results than others. The optimized design reduced crosstalk to approximately -21.9 dB and had an insertion loss of -4.36 dB and a 3 dB passband width, that is, approximately 65% of the channel spacing

Highly compact 2x2 multimode interference coupler in silicon photonic nanowires for array waveguide grating demodulation integration microsystem

A highlycompact2x2 multimodeinterference(MMI)couplerbasedonsilicon-on-insulatorthatcanbe used inanarraywaveguidegratingdemodulationintegrationmicrosystemisdesigned.Thecoupleris simulatedusingthebeampropagationmethod.Taperwaveguidesareusedasinput/outputwave- guides. ThefootprintoftheMMIregionisonly6 mmx57 mm.Theexcesslossis0.46dB,andthe uniformityis0.06dBwithtransverseelectricpolarizationwhenthecenterwavelengthis1.55 mm. The maximumexcesslossis1.55dBintherangeof1.49 mm-1.59 mm.Thesimulationresultsshowthat a small2x2 MMIcouplerexhibitslowexcessloss,widebandwidth,andgooduniformitysuitablefor the requirementsofthesystemonchip

Design of 1x8 silicon nanowire arrayed waveguide grating for on-chip arrayed waveguide grating demodulation integration microsystem

The integration of fiber grating demodulation system is a research emphasis in the study of demodulation systems. On-chip arrayed waveguide grating (AWG) demodulation integration makes integration possible in a demodulation system. A 1x8 silicon nanowire AWG for on-chip AWG demodulation integration microsystem is proposed and designed. The center wavelength is 1550.918 nm, the waveguide width is 350 nm, the waveguide thickness is 220 nm, and the effective area is 267x259  μm2. The single-mode waveguide cross-section structure is designed according to the refractive index of the silicon-on-insulator material. The mask layout territory of the 1x8 AWG is designed and optimized using the beam propagation method. A cone-shaped mold spots converter is proposed in the design process. Furthermore, the wavelength-division-multiplexing-phasar simulation system is established to simulate the stable output optical propagation characteristics of the designed AWG. The simulation result shows that the insert loss of the AWG is 10.658 dB, and the crosstalk is 3.037 dB, which is lower under the same waveguide, thickness, and size. This condition makes the AWG design the best choice for a fiber Bragg grating demodulation microsystem

Optimal Design of an Ultrasmall SOI-Based 1 × 8 Flat-Top AWG by Using an MMI

Four methods based on a multimode interference (MMI) structure are optimally designed to flatten the spectral response of silicon-on-insulator-(SOI-) based arrayed-waveguide grating (AWG) applied in a demodulation integration microsystem. In the design for each method, SOI is selected as the material, the beam propagation method is used, and the performances (including the 3 dB passband width, the crosstalk, and the insertion loss) of the flat-top AWG are studied. Moreover, the output spectrum responses of AWGs with or without a flattened structure are compared. The results show that low insertion loss, crosstalk, and a flat and efficient spectral response are simultaneously achieved for each kind of structure. By comparing the four designs, the design that combines a tapered MMI with tapered input/output waveguides, which has not been previously reported, was shown to yield better results than others. The optimized design reduced crosstalk to approximately −21.9 dB and had an insertion loss of −4.36 dB and a 3 dB passband width, that is, approximately 65% of the channel spacing