With the development of integrated photonic circuits, optical waveguide microdisk resonators (MRR) devices which can be easily integrated with photonic chips are becoming more and more important in optical communication systems. As the core execution unit to improve response sensitivity, field-programmable gate array, optical waveguide MRR has high applicability in esonators due to its smaller mode volume, and larger free spectral range (FSR). Specially, SOI waveguide fabrication technology is easy to be compatible with CMOS foundry processing and integrated circuit technology with smaller size and lower cost, so it can overcome the shortcomings of micro resonators fabricated by other materials. And SOI waveguide MRR has important research significance and distinguished application prospects, which has considered to be the future large-scale integrated photonic circuit basic devices. Because of its powerful optical signal processing ability, MRR has been widely used in various optical systems. With the advantages of simple manufacturing process, ease integration, and multitudinous functions, the waveguide MRR has become the basic structural unit of integrated photonic system and considered as the basic device of large-scale integrated optical path. Based on the high thermo-optic (TO) coefficient of Si material, the tunable function of the SOI MRR can be realized by TO modulation. A waveguide MRR with large tuning range, low optical transmission loss, simple electrode fabrication method, and high TO efficiency is proposed. In order to enhance the applicability of the designed SOI waveguide MRR at different wavelength bands, a tunable SOI MRR was designed.
A four-order asymmetric Y-junctions mode (de)multiplexer ((de)MUX) was theoretically proposed for highly integrated on-chip mode-division systems. The high-order mode in the stem waveguide of asymmetric Y-junctions is designed to be separated from the lower-order mode and evolve into the fundamental mode in the narrow arm. Through the widths optimization of branch arms by effective index matching and beam propagation method, the footprint of four-order mode (de)MUX was controlled to be 140×7.1μm2. The calculated excess loss and crosstalk were less than 0.3 dB and -18 dB within the operation wavelength range from 1460 to 1660 nm, respectively. This scheme may be expanded to higherorder modes (de)MUX design.
Dynamic optical power distribution has great importance to network optimization. A three-dimensional (3-D) polymer thermo-optic switch is designed and fabricated to work at 650 nm. Two rectangular poly(methyl-methacrylate-glycidly-methacrylate) waveguides in neighboring and parallel layers couple with each other in a vertical direction. The lightwave is routed in two layers through a metal heater control. Waveguide configuration and relative position are optimized theoretically through beam propagation method calculations. The fabricated switch demonstrates an extinction ratio of 27.5 dB at a driving power of 57.7 mW. Measured rise time and fall time are 639.8 and 758.2 μs, respectively. Reliability characterizations within 125 days prove good operation stability at different extinction ratios. This work has potential in 3-D optical connections and visible light communication.
Erbium-doped Polymer hybrid slot waveguide amplifier at λs=1530 nm with a 1480 nm pumping wavelength is investigated. Both, the waveguide structure parameters and the Er3+-doped polymer intrinsic spectroscopic parameters are swept to analyze the gain contribution sensitivities. Assuming moderate optical transmission losses of 10dB/cm, the predicted net gain typically varies from 0 to 10dB. Due to the excited state absorption (ESA) mechanism in the high intensity slot region, the signal gain is significantly suppressed for large pumping power, leading to the counterintuitive result that there is an optimum pump power value in the sub-100 mW range. The effect of the ion concentration and the ion-ion interaction is considered giving different adjusted parameters in every particular case.
A novel kind of wavelength-insensitive wide-spectrum polymer electro-optic (EO) switch is proposed by employing two symmetric active Mach-Zehnder interferometers (MZIs), a passive middle directional coupler and a pair of passive phase-generating couplers. Extinction ratio compensation condition under off-state and insertion loss compensation condition under on-state are derived to expand wavelength spectrum. With sufficient consideration of the wavelength dispersion of material and waveguide, optimization, and simulation were performed. The switch exhibits a switching voltage of 4.96 V with each MZI EO region length of 5000 μm. An S-C-L band (1460 to 1625 nm) covering a wide-spectrum more than 165 nm was obtained, and within this range, an extremely high extinction ratio more than 40 dB and an insertion loss within 1.8 to 11.9 dB were reached. This spectrum was more than 8 times of that of the traditional MZI EO switch (only 20 nm).The proposed device can function normally at any wavelength, and is an ideal candidate for a broadband photonic switching element in next-generation nonwavelength selective optical networks-on-chip.
A low-power 2×2 multimode interference-Mach Zehnder interferometer thermo-optic switch is proposed and fabricated using a cross-linkable negative photoresist as core material. The waveguide can be easily fabricated by direct ultraviolet photolithography and wet etching processes. The experiment results show that the switch has a low switching power of 6.9 mW and a switching time of 0.4 ms.
A dual-driving polymer Mach-Zehnder interferometer (MZI) electro-optic switch is designed and optimized, which consists of a phase-generating coupler (PGC) and a 3-dB directional coupler. Structural schematics and principles of the PGC and the switch are described. Novel formulas of the switching time are presented. Under the central operation wavelength of 1550 nm, simulation for the designed device shows that the push-pull switching voltage is 2.445 V, the switching time is 18.1 ps, and the cross talk is less than −30 dB. By optimizing the PGC structure, the phase error resulting from the wavelength shift can be compensated effectively, and a wide spectrum about 110 nm can be achieved. The proposed analytical technique on waveguides and electrodes proves to be accurate and computationally efficient when compared with the beam propagation method (BPM) and the experimental results.
A 33×33 thermo-optic tunable arrayed waveguide grating (AWG) is fabricated using the poly (2,3,4,5,6-pentafluorostyrene-co-glycidylmethacrylate) (PFS-co-GMA). The fabrication process of the device is depicted, and the measured results are presented. The measured insertion loss is between 8.5 dB for the central channel and 10 dB for the edge channels, the crosstalk is below −20 dB, the wavelength channel spacing is 0.8 nm, and the 3-dB bandwidth is 0.35 nm. The measured wavelength/temperature shift rate is about −0.12 nm/K. The central wavelength is 1545.21 to 1551.81 nm in the temperature range from 10 to 65°C. The tuning range is −6.6 nm.
Highly transparent TiO2/SiO2 films prepared using sol-gel technique doped with organic azo dye, Disperse Red 1(DR1)
have been investigated. Processing parameters such as spin speed, spin time, and ambient atmosphere, and solution
synthesis parameters such as catalysis method, alcohol dilution ratio, and component molar percentages, may affect the
film formation. The refractive index increases follow along with the raising of the molar ratio between TiO2 and SiO2.
When the molar ratio between TiO2 and SiO2 is zero, i.e. no titania precursor in the initial solution, the refractive index is
minimum 1.49 at 1300nm, whereas when there is no TEOS in the initial solution, the refractive index is maximum 1.81
at 1300nm. The sol-gel thin film is spin-coated on ITO glass substrate with better uniformity. The electric-optic
coefficient γ33=42pm/V was measured by simple reflection technique at a fundamental wavelength of 1300nm. The
hybrid organic-inorganic sol-gel film is well balanced material in its simplicity for film formation, nonlinearity, and
thermal stability sufficient for device fabrication. Moreover, the measurement system was calibrated and the measured
electric-optic coefficient of the gallium arsenide crystal is in excellent agreement with the known value.
Exact expressions for calculating the electro-optic (EO) coefficients of GaAs and polymer or organic/inorganic hybrid
film using simple reflection technique have been deduced. For different approximate conditions, several expressions
have been contrasted. After strictly verified, the measuring systems are accurately adjusted, and with the measured data
the numerical value of
γ33 can be calculated. The measured EO coefficient of GaAs is in excellent agreement with the
known value. The organic/inorganic hybrid material is prepared by sol-gel process during which dispersed red 1 (DR1) is
doped in tetraethoxysilane (TEOS) as the chromophore with a concentration of approximately 13% by weight. And
γ33
of hybrid material over 20pm/V could be easily obtained.
In this paper, a new fabricating strategy for polymer microring resonators vertically coupled to a bus waveguide is developed. A carefully engineered Al masking process is utilized to compensate the local concave of the buried waveguide formed by polymer spin-coating, realizing perfectly flat top surface of the buried bus waveguide. A serial of the vertically coupled polymer microring resonator showing excellent topology was fabricated with this strategy. The resonance phenomenon is oberved in a PMMA-based microring resonators using this fabricating strategy .The suggested approach is suitable to fabricate vertically coupled polymer micro-resonators.
This paper proposes a design of polymer Triple Ring Resonators Filter (TRRF) based on silicon substrate. The device structure was demonstrated in order to get wide Free Spectral Ranger (FSR) of the device and a box-like filter response. The transmission equation of the amplitude of input and output lightwaves and coupling coefficients were analyzed by coupling mode theory also.
A 32 × 32 arrayed waveguide grating (AWG) multiplexer operating around the 1550 nm wavelength has been designed and fabricated using fluorinated poly (ether ether ketone). The schematic layout is about 3.2×1.7 cm2. For our AWG, the total loss of designed AWG multiplexer is calculated to be 4.5 dB. We fabricated the AWG multiplexer by spin coating, photolithographic patterning and reactive ion etching (RIE). The core size is 5×5 μm2. The roughness of polymer surface was reduced by 20 nm using a remelting technique. The measured wavelength channel spacing of the fabricated AWG multiplexer is 0.796 nm and center wavelength is 1548 nm. The inserting loss of the AWG is 9.5 dB and crosstalk less than -20 dB.
A method for measuring the electro-optic coefficient of poled polymer films on the basis of an asymmetry Fabry-Perot cavity is described. Two aluminum films were deposited on glass substrate by thermal evaporation in high vacuum to form high reflection mirror and low reflection mirror, respectively. Nonlinear polymer thin films are spin coated on low reflection mirror and poled by corona poling in order to break the internal centrosymmetry. Then the sample layers are placed upside down on the high reflection mirror. The sandwich structure is objected to a laser beam, and a variable voltage is applied the aluminium films resulting in a modulation of the transmitted laser power. The electro-optic coefficient γ13 of the poled polymer film can be calculated by evaluating the Fabry-Perot equation. The spatial resolution is tested with a polymer film that was poled by a needle corona discharge in air through a metal grating with a period of 120 microns. By scanning the sample plate in the direction perpendicular to the grating lines, the spatial resolution is also demonstrated according to the spacing of the poled structure.
Based on formulas presented for the amplitude coupling ratio and the transfer function, transmission characteristics are analyzed and parameters are optimized for a polymer cross-grid array of microring resonant wavelength multiplexers around the central wavelength of 1.550918 µm with wavelength spacing 1.6 nm. In the design of the device, by means of selecting a resonant order m=95 and introducing a resonant order increment of adjacent filter elements m=2, we increase the ring radius difference of adjacent filter elements R from 17 nm (for the case of m=0) to 337 nm. Calculated results show that the 3-dB bandwidth is about 0.2 nm, the ratio between the –1- and –10-dB bandwidths is about 0.22, the insertion loss is less than 0.5 dB, and crosstalk is below –39 dB for each of the eight horizontal output channels.
Based on formulas presented, optimization design is performed and the effects of manufacturing tolerances on transmission characteristics are analyzed for a polymer microring resonant wavelength multiplexer around the central wavelength of 1.550918 µm with wavelength spacing 1.6 nm. Modeling results show that the insertion loss is less than 0.55 dB and crosstalk is less than –21 dB for each of eight vertical output channels of the designed device without tolerances. Some manufacturing tolerances result in a shift of the transmission spectrum and lead to increases of the inserted loss and crosstalk over the design case without tolerances
The diffraction characteristics are analyzed for a polymer arrayed-waveguide grating (AWG) multiplexer around the central wavelength of 1.55 μm with the wavelength spacing of 1.6 nm. The diffraction loss and diffraction efficiency in the input and the output slab waveguide are investigated and discussed for different values of parameters, such as the core width, pitch of adjacent waveguides, the number of arrayed waveguides, taper end width of waveguides, and number of output wavelength. Finally, we give a set of parameters which have been optimized in this device.
A new rnethod, based on zero point of longitudinal electric field, was used to deterrnine the spatial resolution of electro-optic (EO) probing systern. To examine the spatial resolution of internal and external EO probing systems, an interdigital structure is fabricated on GaAs substrate with and without a layer of Si02 between the electrode and the substrate respectively. Considering Si02 layer or air gap between electrode and EO crystal, the result of electro-optic probing was simulated which is well accorded with experiment. The result indicates that spatial resolution of less than 0.5um and lum are obtained in internal and external EO probing system respectively.
Based on the arrayed waveguide grating (AWG) multiplexer theory, some important parameters are optimized for the structural design of a polymer AWG multiplexer around the central wavelength of 1.55μm with the wavelength spacing of 1.6 nm. These parameters include diffraction order, focal length of slab waveguides, number of arrayed waveguides are determined. Then, a schematic waveguide layout of this device is presented, which contains 9 input and 9 output channels. The transmission and loss characteristics are analyzed. The computed results show that when we select the core thickness as 4 micron, width as 6 micron, pitch of adjacent waveguides as 26 micron, diffraction order number as 78, distance between the focal point and the origin as 8340 micron, the total loss of the device can be dropped to about 5.7dB, and the crosstalk among output channels can be dropped below -50dB.
In this paper, the basic principle, details of fabricating process and measuring results were described for a polymer/Si arrayed waveguide grating (AWG) multiplexer around the central wavelength of 1.550 micron with the wavelength spacing of 1.6nm. The fluorinated polymer was used to fabricate AWG to reduce the optical loss, but the fluorinated material was expensive, so we initially adopted the polymer of polymethylmethacrylate(PMMA) type to go on technologic research. The regulated curve of refractive index was given for the core polymer. In order to obtain better shape of the waveguide after the reactive ion etching (RIE) using oxygen, an aluminum film as mask was used on polymer instead of conventional photoresist as mask. In order to reduce radiation loss of underciadding layer to Si
substrate, the underciadding layer thickness was increased to 11 micron through two times of spin-coating, thus the radiation loss was reduced to the order of 0.001dB. The measuring results indicates fabricated optical waveguide achieved single-mode transmission.
In this paper, a 9 X 9 Polymer/Si AWG was designed and fabricated. The cladding material is poly-methyl-methacrylate-co-glyciclyl methacrylate (PMMA-GMA) and the core material is the mixture of
PMMA-GMA and bis-phonel-A epoxy. During the fabrication process of the Polymer/Si AWG device, We used aluminum as mask on polymer instead of conventional photoresist as mask. The results show that the device is good for the wavelength division multiplexing (WDM) system. The output characteristics of the device were measured by a system based on the tapered fiber. The results show that our polymer/Si AWG meets the designed device well.
An arrayed-waveguide grating multiplexer is demonstrated, which is successfully designed and fabricated . A wavelength channel spacing was 1 .6nm, a crosstalk of less than —20dB and the insertion loss was 7-12dB around 1.55?m. The polarization-dependent wavelength shift was very small without special compensation methods.
Electro-optic modulation has been first demonstrated using a poled electro-optic polymer films, placed in a Fabry-Perot cavity. In our configuration, incorporating an electro-optic material in the spacer layer of a Fabry-Perot device creates such a structure whose optical transmission characteristics depend on the applied voltage. And the longitudinal electro- optic modulation, in which the direction of the poling electric field, the applied electric field and the light traveling are parallel with one another and perpendicular to the surface of the polymer film, is applied. According to the electro-optic tensor of a poled polymer film, there is no birefringence effect and only phase modulation of the light is produced. Considering the interferometric nature of the Fabry- Perot cavity, the phase modulation can be converted to the amplitude modulation. The cavity used had a finesse of about 20. The thickness of film is about 1 micrometers . The modulation depth achieved was about 0.07% for a low ac field of 1V/micrometers . The results are promising for the study of array modulation and optical interconnection.
On the basis of the arrayed waveguide grating (AWG) multiplexer theory, some important parameters are optimized for the structural design of a polymer AWG multiplexer around the central wavelength of 1.55micrometers with the wavelength spacing of 1.6nm. These parameters include the thickness and width of the guide core, mode effective refraction indicees and group refractive index. Pitch of adjacent waveguides, diffraction order, path length difference of adjacent arrayed waveguides, focal length of slab waveguides, free spectral range, number of input/output waveguides, and that of arrayed waveguides.
A second-order nonlinear optical polymer was synthesized with bis-phenol-A as the polymer backbone, p-nitroaniline as the chromophore and cinnamyl group as the photo-sensitizer. The polymer films were obtained by spin-coating and poling by three methods respectively. These methods of poling include needle electrode corona poling, parallel wire electrode corona poling and contact poling, which were used to obtain the molecular orientation. The uniformity of the side-chain polymer films have been studied by external electro-optic measurement. The spatial resolution of system is 3 micrometers . Experimental results demonstrated that parallel wire electrode corona poling is easier to obtained large poled area with good uniformity than that of other methods.
Selective proton bombarded buried stripe lasers have been developed using the tungsten filaments as a mask to proton bombard the current-blocking area. High reliability has been shown in high temperature accelerated aging tests. For the selective proton bombarded buried crescent laser diodes, the output power of 150 mW, the small signal modulation bandwidth in excess of 11 GHz for the 250 micrometer cavity length and full area electrode, and the shortest gain switched laser pulses of 7 ps FWHM by combined DC and microwave current injection are achieved.
Introduced the construction of the experiment system of the laser probe measurements based on electro-optic sampling technique. Analyzed the relationship between the width of the optical pulses and the signal noise ratio of detection. The function of different stage circuit internal to the high-speed dynamic divider circuit chip have been measured with the double-frequency phase sweeping technique. A detail analysis about the chip failure have been given.
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