Analysis of a 1×32 polymer microring resonant wavelength de-multi/multiplexer assistant with interleave filter

A new 1×32 wavelength de-multi/multiplexer utilizing the microring resonator and interleave filter is proposed in this paper. A novel formula of transfer functions is presented, the parameters of microring are optimized, and the transmission characteristics of the system are analyzed. The channel spacing of the presented device is 0.4 nm. The analytical result shows that the crosstalk between adjacent channels can be reduced greatly and the filter response of the device can be improved by using the interleave filter. A bandwidth (3 dB) of 0.21 nm, an insertion loss less than 1.1 dB, and crosstalk below −32 dB were obtained for the optimized device. A method for compensating the manufacturing tolerances is discussed.     

32-channel arrayed waveguide grating multiplexer using low loss fluorinated polymer operating around 1550 nm

A 32 × 32 arrayed waveguide grating (AWG) multiplexer operating around the 1550 nm wavelength has been designed and fabricated using highly fluorinated polyethers. The propagation loss of the slab waveguide is about 0.3 dB/cm at 1550 nm wavelength. The channel spacing of the AWG multiplexer is 0.8 nm (100 GHz). The insertion loss of the multiplexer is 10.3-15.3 dB and the crosstalk is less than −20 dB.     

Compact SOI arrayed waveguide grating demultiplexer with broad spectral response

A compact eight-channel flat spectral response arrayed waveguide grating (AWG) multiplexer based on silicon-on-insulator (SOI) materials has been fabricated on the planar lightwave circuit (PLC). The 1-dB bandwidth of 48 GHz and 3-dB bandwidth of 69 GHz are obtained for the 100 GHz channel spacing. Not only non-adjacent crosstalk but also adjacent crosstalk are less than −25 dB. The on-chip propagation loss range is from 3.5 to 3.9 dB, and the total device size is 1.5 × 1.0 cm².     

Effect of bending on characteristics of a polymer microring resonant wavelength multiplexer

Novel formulas of transfer functions are presented, some parameters are optimized, and bending effect of microrings on characteristics is analyzed for a polymer microring resonant wavelength multiplexer (MRRWM) around the central resonant wavelength of 1.55 μm with the wavelength spacing of 1.6 nm and with eight vertical output channels. Simulated results show that the bending of microrings causes the variation of the propagation constant, leads to the shift of the transmission spectrum, and increases the insertion loss. A method is proposed for eliminating the shift of the transmission spectrum and realizing the accurate demultiplexing of the device. The polymer MRRWM designed possesses the 3-dB bandwidth of 0.2 μm, insertion loss less than 0.57 dB, and crosstalk below −20 dB for every vertical output channel.     

Characteristic Analysis of a Smooth Square Microring Resonant Wavelength Multiplexer

Novel formulas of amplitude coupling ratio and transmission functions are presented for a smooth square microring resonant (MRR) wavelength multiplexer. By using these formulas, transmission characteristics are analyzed and some parameters are optimized for such a 1 × 8 polymeric device around the central wavelength of 1550.92 nm with the wavelength spacing of 1.6 nm. In the design of the device, by using the smooth squares, a thicker coupling layer is obtained, and by resonating the light at different resonant orders in different filter elements, the ring radius increment is increased sufficiently, which is of benefit to the fabrication of the device. When the amplitude coupling ratio is 0.2, the 3-dB bandwidth of the spectral response is about 0.2 nm; the ratio between -1 dB and -10 dB bandwidths is about 0.2; the insertion loss is less than 1.33 dB; and the crosstalk is below -21 dB for every vertical output channel of the device.     

Multiwavelength erbium-doped fiber laser employing a nonlinear optical loop mirror

A stable and broad bandwidth multiwavelength erbium-doped fiber laser is proposed and demonstrated successfully. A nonlinear optical loop mirror which induces wavelength-dependent cavity loss and behaves as an amplitude equalizer is employed to ensure stable room-temperature multiwavelength operation. Up to 50 wavelengths lasing oscillations with wavelength spacing of 0.8 nm within a 3-dB spectral range of 1562-1605 nm has been achieved. The measured power fluctuation of each wavelength is about 0.1 dB within a 2-h period.     

An ultra compact photonic crystal wavelength division demultiplexer using resonance cavities in a modified Y-branch structure

An ultra small size 4-channel wavelength division demultiplexer based on 2D photonic crystal modified Y-Branch, suitable for integration, is proposed in this paper. The output wavelengths of designed structure can be tuned for communication applications (around 1550 nm) by choosing suitable defect parameters in the corner of each resonance cavity and output waveguides. The cross section of the structure is 313.28 μm² (17.8 μm × 17.6 μm) and desirable for integration based on popular planar technology. The bandwidth of each channel is near to 1 nm and the channel spacing is approximately 3.5 nm and wavelengths of demultiplexer channels are 1548.8 nm, 1551.9 nm, 1555.4 nm and 1559.3 nm respectively. Also, the crosstalk is between −33.1855 dB and −10.4947 dB. Furthermore, the mean values of the crosstalk and quality factor are −22.54 dB and 1496.7 respectively.     

Skin-effect analysis of a shielded polymer Y-fed coupler electro-optic modulator over a wide bandwidth of 94 GHz

A novel technique and related formulations are proposed for analyzing the influences of the skin-effect on the performances of a polymer Y-fed coupler electro-optic modulator with shielded push-pull micro-strip electrodes. Using the extended point-matching method, coupled mode theory and electro-optic modulation theory, thorough design and optimization are performed. By introducing the effective applied voltage, formulas of the high-frequency response under skin-effect are deduced, and characteristics under skin-effect are analyzed. Under the central wavelength of 1550 nm, the half-wave voltage is as low as 1.097 V for the device with an active region length about 8.884 mm. Considering the influences of the skin-effect, the 3-dB modulating bandwidth of the microwave signal is up to 94 GHz. A high extinction ratio of more than 20 dB and a low insertion loss of less than 4.18 dB are achieved when the microwave frequency is below 68 GHz under skin-effect. This design technique is proven to be accurate by the comparison with the beam propagation method (BPM).     

Modeling of arrayed waveguide grating for wavelength interrogation application

We have proposed and discussed a design of arrayed waveguide grating (AWG) for the application of wavelength interrogation. The spectral responses of a silica-based 16 channel AWG with channel spacing 1.6 nm have been simulated when different receiver waveguide spacing are used. It was found that the 3-dB bandwidth is reduced about 50% as the receiver waveguide spacing increasing from 20 μm to 30 μm. The effect of bandwidth of the spectral response on wavelength resolution of AWG based interrogator has been estimated and discussed.     

Polymeric arrayed waveguide grating using imprint method incorporating a flexible PDMS stamp

A polymeric arrayed waveguide grating (AWG) has been proposed and demonstrated by employing the nanoimprint method. A flexible PDMS (polydimethylsiloxane) stamp with the device patterns engraved was developed from a rigid master mold made of quartz glass, featuring uniform precision contact with and easy separation from polymer films. The device was fabricated by replicating the pattern on the stamp in a core polymer layer, with no etching process involved. For our device, the number of the output channels is eight and the center wavelength of each output channel is positioned from 1543.7 nm to 1548.3 nm with the spacing of 0.8 nm. The achieved channel crosstalk was about 10 dB and the 3 dB bandwidth approximately 0.8 nm.     

A new design of tunable four-port wavelength demultiplexer by photonic crystal ring resonators

A four-channel wavelength demultiplexer based on photonic crystal ring resonators (PCRR), which can be used for photonic integrated circuits, is designed. Dropping efficiency and Q factor of single improved ring are 100% and 842, respectively. In order to achieve the structure of demultiplexer, three improved rings have been used, that every ring has an individual inner rod radius; it means that each ring has a varying resonant wavelength. The results of simulation using finite-difference time-domain (FDTD) method in our proposed structure reveals an average transmitted power higher than 90% for each output port, Channel spacing is about 8 nm and bandwidth for each individual channel is about 2.8 nm. The mean value of the crosstalk between output channels and the area of the proposed structure are about −29 dB and 317 μm², respectively. By changing the radius of inner rods, various wavelengths can be chosen, therefore this device is tunable.     

Numerical analysis of a direct UV-written 1 × 8 double smooth octagon microrings resonant wavelength demulti/multiplexer

A microring resonant wavelength demulti/multiplexer (MRRWDM) based on UV-written technology is designed. By using a double smooth octagon microrings structure, a 1 × 8 device around the central wavelength of 1550.918 nm with the wavelength spacing of 1.4 nm is presented. Analytical results based on coupled mode theory show that the 3 dB bandwidth is about 0.22 nm, the insertion loss is less than 0.7 dB, and the crosstalk is below ?47 dB for every output channel of the designed device without tolerances.     

Design of wide-spectrum polymer Mach-Zehnder interferometer electro-optic switches using two symmetric N-th order phase-generating couplers

To enlarge the output spectrum, a novel reasonable structure of one kind of Mach-Zehnder interferometer (MZI) electro-optic (EO) switches containing two symmetric N-th order phase generating couplers (PGCs) is presented, and thorough model, analysis and design technique are proposed. A non-linear least square method is investigated for optimizing the PGC structure to eliminate the phase difference error caused by the wavelength variation. Under the central wavelength of 1550 nm, optimization and simulation are performed on three MZI EO switches using two first, second and third order PGCs, respectively. The switches exhibit a low switching voltage of 1.156 V with an active region length of 4 mm. The output spectrums covering the whole S-C-L bands are as wide as 320, 390 and more than 435 nm, respectively, the insertion loss are less than 5.57, 5.98 and 7.90 dB, respectively, and the crosstalk is less than −30 dB over the wide wavelength ranges, for the three designed switches. The design technique is supported to be feasible by the comparison with beam propagation method (BPM).     

A novel 4-channel demultiplexer based on photonic crystal ring resonators

A 4-channel wavelength division demultiplexer based on photonic crystal structures suitable for WDM communication applications is proposed. In order to improve the wavelength selectivity we introduce four scattering rods above and under the X-shaped ring resonators in the proposed structure. It is shown that the PBG of the structure is tuned for communication systems in both TE and TM modes but the results demonstrated that just the first PBG in TM mode is suitable for WDM applications, so all the simulations will be done in TM mode. The minimum and maximum crosstalk between channels is −23.7 dB and −7.5 dB, respectively. Also, the average channel spacing in this structure is 3 nm.     

Optimal design and analysis of a high-speed, low-voltage polymer Mach-Zehnder interferometer electro-optic switch

Detailed model, analysis and design technique are presented for simulating a high-speed polymer Mach-Zehnder interferometer (MZI) electro-optic switch with push-pull dual driving electrodes and rib waveguides. The novel formulas of the time-domain response are derived. Thorough optimization and simulation for the designed device are performed. The total length of the basic function unit of the switch is about 5049 μm, the push-pull switching voltage is 2.23 V, the switching time is 18.1 ps, and the insertion loss and crosstalk are less than 2.64 and −30 dB, respectively, within the range of the operation wavelength from 1534 to 1566 nm. These results are in good agreement with those obtained from the beam propagation method (BPM).     

Parameter optimization and characteristic analysis of a polymer microring resonant wavelength multiplexer

Novel formulas of transmission functions are presented, some parameters are optimized, and transmission characteristics are analyzed for a polymer microring resonant wavelength multiplexer around the central wavelength of 1.55 μm with the wavelength spacing of 5.6 nm and with eight vertical output channels. The computed results show that the designed device possesses some excellent features including the 3 dB bandwidth of 0.25 μm, weaker background light of 3.8×10⁻⁴, smaller inserted loss of less than 0.6 dB, and lower crosstalk below −20 dB for every vertical output channel.     

Micromachined high frequency PMN-PT/epoxy 1-3 composite ultrasonic annular array

This paper reports the design, fabrication, and performance of miniature micromachined high frequency PMN-PT/epoxy 1-3 composite ultrasonic annular arrays. The PMN-PT single crystal 1-3 composites were made with micromachining techniques. The area of a single crystal pillar was 9 × 9 μm. The width of the kerf among pillars was ∼5 μm and the kerfs were filled with a polymer. The composite thickness was 25 μm. A six-element annular transducer of equal element area of 0.2 mm² with 16 μm kerf widths between annuli was produced. The aperture size the array transducer is about 1.5 mm in diameter. A novel electrical interconnection strategy for high density array elements was implemented. After the transducer was attached to the electric connection board and packaged, the array transducer was tested in a pulse/echo arrangement, whereby the center frequency, bandwidth, two-way insertion loss (IL), and cross talk between adjacent elements were measured for each annulus. The center frequency was 50 MHz and −6 dB bandwidth was 90%. The average insertion loss was 19.5 dB at 50 MHz and the crosstalk between adjacent elements was about −35 dB. The micromachining techniques described in this paper are promising for the fabrication of other types of high frequency transducers, e.g. 1D and 2D arrays.     

A photonic wire-based directional coupler based on SOI

A photonic wire-based directional coupler based on SOI was fabricated by e-beam lithography (EBL) and the inductively coupled plasma (ICP) etching method. The size of the sub-micron waveguide is 0.34 μm × 0.34 μm, and the length in the coupling region and the separation between the two parallel waveguides are 410 and 0.8 μm, respectively. The measurement results are in good agreement with the results simulated by 3D finite-difference time-domain method. The transmission power from two output ports changed reciprocally with about 23 nm wavelength spacing between the coupled and direct ports. The extinction ratio of the device was between 5 and 10 dB, and the insertion loss of the device in the wavelength range 1520-1610 nm was between 22 and 24 dB, which included an about 18.4 ± 0.4 dB coupling loss between the taper fibers and the polished sides of the device.     

Polymer waveguide thermo-optic switches with −70 dB optical crosstalk

To reduce the crosstalk of the polymer waveguide optical switches, waveguide attenuators are integrated with the switch on the same substrate. The switch and attenuator shares a single connected electrode which is controlled by a single current source. Due to the simple structure of the integrated attenuator, the device length is reduced to 10 mm so as to provide low insertion loss of 0.8 and 1.1 dB for 1300 and 1550 nm, respectively. Further radiation of the remained optical signal on the switch-off branch is induced by the integrated attenuator so that the switching crosstalk is reduced to −70 dB with an applied electrical power of 200 mW. The low crosstalk is maintained for the environmental temperature range of −10 to 55 °C.     

Programmable all-fiber structured waveshaper based on linearly chirped fiber Bragg grating and digital thermal controller

We proposed and experimentally demonstrated an all-fiber structured programmable optical bandpass filter (waveshaper) based on a linearly chirped fiber Bragg grating and a digital-controlled thermal array. The key parameters of this filter such as the number of transmission channels, passing bandwidth per channel, central wavelength as well as the channel spacing can be reconfigured independently and flexibly by a program-controlled circuit. We have achieved in experiments the tunable passing bandwidth ranging from < 0.04 to 1.55 nm, adjustable central wavelength ranging from 1,547.16 to 1,558.64 nm, and a minimum wavelength spacing of 0.91 nm. The insertion loss of the whole device and the sideband rejection ratio are about 1.76 and 28 dB, respectively.