Planar Polymer Waveguides Research Articles

Optical Properties of Nd3+ in Nd(DBM)3Phen-doped Poly(methyl methacrylate)

Nd(DBM)3Phen-doped (DBM is dibenzoylmethane and Phen is phenanthroline) polymethyl methacrylate (PMMA) is prepared. Optical absorption, excitation and emission spectra were analyzed for Nd3+ in Nd(DBM)3Phen-doped PMMA. Using the Judd-Ofelt theory, the absorption spectrum was analyzed. The Judd-Ofelt(J-O) intensity parameters of Nd(DBM)3Phen-doped polymethyl methacrylate were calculated to be 2 = 20.971020 cm2, 4 = 3.421020 cm2, 6 = 2.901020 cm2. The radiative lifetime (631 s) of the excited 4F3/2 level is given. The stimulated emission cross-sections and the fluorescence branch ratios for the 4F3/2 4IJ' transitions are also evaluated. Analysis reveals that Nd(DBM)3Phen-doped PMMA is promising for application in polymer optical fibers and planar waveguides.

Low-loss and highly polarized emission from planar polymer waveguides

The waveguiding properties and amplified spontaneous emission (ASE) of a blend of light-emitting gain-conjugated polymers were investigated. ASE-induced line narrowing occurs for excitation fluences larger than 100 microJ cm(-2), with a maximum optical-gain coefficient of 8 cm(-1). Energy transfer between the host and guest polymers, significantly reducing the self-absorption, leads to a loss coefficient of the waveguide as low as 0.3 cm(-1), which is believed to be the lowest value reported for active organic gain slabs and a highly polarized emission, with a polarization contrast up to 0.65. These results indicate that gain-conjugated polymer blends are state-of-the-art organic materials for lasing devices.

Integration of a multimode interference coupler with a corrugated sidewall Bragg grating in planar polymer waveguides

We demonstrate the integration of a 3-dB multimode interference coupler with a corrugated sidewall Bragg grating in planar polymer waveguides by direct electron beam writing. Both transmission and reflection spectra of the Bragg grating are measured through this integrated device directly. We use the thermooptic effect to tune the integrated waveguide grating, achieving a tuning range of 6.2 nm and a bandwidth variation of 0.3 nm within a temperature change of 62/spl deg/C.

Refractive index change by photoinduction of a UV-sensitive SMF-to-PWG coupler

We fabricated a UV-sensitive photofunctional device using evanescent field coupling between a side-polished single-mode optical fiber (SMF) and photochromic dye-dispersed polymer planar waveguide (PWG). PWG was made by diarylethene derivative [1,2-bis(2,5-dimethylthiophen-3-yl) hexafluoro-cyclopentene (DM-BTE)] with a stability and memory effect by photoinduction. The wavelength response characteristic for UV irradiation time was 3.44 nm (UV irradiation time 60 s), and recovery time was 140 s. The optical attenuation characteristic of 1310-nm wavelength was 0.4 dB in 1 wt% concentration of DM-BTE and 1.65 dB at 10 wt% DM-BTE. The refractive index changes of DM-BTE by photoinduction were /spl Delta/n=0.00067 in the condition of 3 wt% of DM-BTE concentration and 5 mW of UV intensity and 70 s of UV irradiation time.

Polymer thin films and Bragg grating structures based temperature and pressure integrated effects

The analysis of temperature effects on a single guided mode optical fiber coupled into a deposited layer planar waveguide is presented. The pressure effects are investigated through a Bragg grating structure. Using the transfer matrix and mode expansion propagation methods the characteristics of an integrated temperature and pressure sensors are performed. Two kinds of polymers are used as a planar waveguide materials. Employing the thermooptic effects of a polymer planar waveguide, the resonant wavelength of the device is very sensitive to ambient temperature. A relatively good agreement between our results obtained using rigorous approaches and those reported in the experiment is obtained.

Polymers for Electro‐Optical Modulation

Second‐order nonlinear optical (NLO) properties of polymeric materials have been attracting a lot of attention, especially for such potential applications as fast waveguides electrooptic (EO) modulation and frequency‐doubling devices. For these photonic applications, the performance of the NLO materials has to be optimized. This requires not only a fundamental knowledge of inter‐relationship between their chemical and NLO properties, but new technologies competitive or superior to existing ones as well. This review focuses on the synthesis of NLO polymers including chromophore design, and the comparison among comprehensive EO polymer systems. Moreover, characterization and device fabrication of electro‐optical polymer planar waveguides are also reported in this review.

A coupled cavity micro-fluidic dye ring laser

We present a laterally emitting, coupled cavity micro-fluidic dye ring laser, suitable for integration into lab-on-a-chip micro-systems. The micro-fluidic laser has been successfully designed, fabricated, characterized and modelled. The resonator is formed by a micro-fluidic channel bounded by two isosceles triangle mirrors. The micro-fluidic laser structure is defined using photo lithography in 10 μm thick SU-8 polymer on a glass substrate. The micro-fluidic channel is sealed by a glass lid, using PMMA adhesive bonding. The laser is characterized using the laser dye Rhodamine 6G dissolved in ethanol or ethylene glycol as the active gain medium, which is pumped through the micro-fluidic channel and laser resonator. The dye laser is optically pumped normal to the chip plane at 532 nm by a pulsed, frequency doubled Nd:YAG laser and lasing is observed with a threshold pump pulse energy flux of around 55 μJ/mm 2. The lasing is multi-mode, and the laser has switchable output coupling into an integrated polymer planar waveguide. Tuning of the lasing wavelength is feasible by changing the dye/solvent properties.

Widely tunable filter based on side-polished polarisation-maintaining fibre coupled with thermo-optic polymer overlay

A wide wavelength tunable filter based on a side-polished polarisation-maintaining fibre in contact with a polymer planar waveguide overlay is proposed and demonstrated. The good thermo-optic effect of the polymer waveguide induced by a micro-strip heater leads to a wide tunable wavelength range of 230 nm with an applied electrical power of 0.76 W.

Optical amplification of the cutoff mode in planar asymmetric polymer waveguides

Modes with low threshold for optical gain were observed at wavelengths close to the cutoff in experiments probing the amplified spontaneous emission of light-emitting polymer thin films. The polymer was the semiconductor layer in a multilayer semiconductor–insulator–metal structure that simulates the one-dimensional waveguide characteristics in the channel of a field-effect transistor. The “cutoff” mode propagates at the polymer/gate-insulator interface, has an optical gain threshold of approximately 10 kW/cm2, and is not influenced by absorption of the gate electrode. The wavelength of the amplified emission tracks the cutoff wavelength of the asymmetric double-waveguide structure and the cutoff mode is, therefore, tunable in wavelength. Our results suggest that the light-emitting field-effect transistor architecture is a promising route for the construction of an injection laser.

광기능성 폴리머의 소산장 결합을 이용한 측면연마 광섬유형 자외선 센서

측면연마된 광섬유와 광기능성 색소가 분산된 평면도파로 결합기를 이용한 새로운 형태의 자외선 센서를 제작하여 그 특성을 측정하였다. 자외선 조사에 의해 유효굴절률이 변화하는 광변색성 색소가 분산된 폴리머를 평면 도파로 재료로 사용하였다. 박막 광도파로는 광변색성 색소인 스파이록사진을 사용하였다. 자외선 조사시간을 20초, 30초, 40초로 증가시켰을 경우 센서의 파장응답은 1.44nm/mW, 1.64nm/mW, 1.78nm/mW였고 1550nm 파장에서 센서의 90% 복귀시간은 100초로 나타났다. In this paper, we investigated a novel UV sensor using evanescent field coupling between the side polished fiber and photo-functional polymer waveguide. It was found that resonant wavelength shifts occur due to variation in the refractive index of polymer planar waveguide for its photo-functional properties on exposed UV. Spiroxazine (photochromic dye) was used as the planar waveguide. The resonant wavelength responses were exhibited at 1.44 nm/mW, 1.64 nm/mW, and 1.78 nm/mW when UV irradiations were exposed for 20 seconds, 30 seconds, and 40 seconds, respectively. The recovery time of sensor was independent of UV exposure power and 90% recovery time was 100 seconds.

Fabrication and characterization of planar and channel polymer waveguides. III. Compositional distribution and solute loss in polymer thin films

AbstractFor many microelectronic and optoelectronic applications, polymer thin films require the addition of small molecules. However, the thin‐film geometry and associated processing techniques will influence the final morphology and compositional distribution of the constituents. It is therefore important that these be examined directly rather than inferred from bulk measurements. As an example system, the concentration and distribution of Disperse Red 1 (DR1) molecules in poly(methyl methacrylate) thin films were examined. Ultraviolet visibility spectroscopy and dynamic secondary ion mass spectrometry indicate that the composition of the molecules decreased dramatically with thermal treatment of the film. The sublimation of the chromophore was observed to occur at temperatures well below the melting point of the small molecule and the glass transition of the pure polymer; this solute loss manifested itself in changes in the glass transition temperature of the film. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2021–2024, 2002

Investigation of thermo-optically tunable fiber-to-planar waveguide coupler

A tunable fiber-to-planar waveguide coupler based on the thermo-optic effect of a polymer film is presented. In the proposed device, a metal strip formed on the polymer planar waveguide performs both electrically as a heater and optically as a clad-layer. The influences of metal-clad thickness on optical transmission characteristics of the coupler are investigated to obtain a structural condition of metal strip heater for high performance. The dynamic variation of the resonant wavelengths and resonance sharpness by change of metal-clad thickness have been observed and explained in terms of the modal properties of the planar waveguide. It has also been demonstrated that the good thermo-optic effect of polymer waveguide makes it possible for the coupler to be used as a wide wavelength tunable filter, a TE/TM selective polarizer and an optical switch. The wavelength tunable range of a fabricated device exceeded 130 nm with 0.6 W of electrical heating power. The response time was determined as 7 ms.

High-sensitivity temperature sensor using a side-polished single-mode fiber covered with the polymer planar waveguide

A temperature sensor based on evanescent field coupling between a single-mode side-polished fiber and a polymer planar waveguide was demonstrated. Due to thermooptic effects of a polymer planar waveguide, the resonance wavelength of the device is very sensitive to ambient temperature. Two kinds of polymers were used as planar waveguide materials. Fabricated sensors have a sensitivity of -0.37 nm//spl deg/C and -0.71 nm//spl deg/C, respectively. We also measured the thermooptic coefficient of employed polymer approximately.

Bragg gratings in planar polydiactylene waveguides and their application in integrated optics

We present the fabrication of high quality non-uniform Bragg gratings in planar poly(4-BCMU) channel waveguides using an optimized photobleaching set-up and report the optical characterization of the resulting photonic band gap. The suitability of our system to all-optical switching phenomena in different geometries as a result of non-linear wave propagation effects will be shown and discussed. Our results contribute to open up the wide field of device applications in integrated optics based on periodically structured planar polymer waveguides.

Fabrication and characterization of planar and channel polymer waveguides. II. Poly(p-phenylene benzobisthiazole) (PBZT) filmsDedicated to the memory of Bruce A. Reinhardt who is no longer with us in this world. Bruce was a loyal friend and a gifted chemist–we all miss his insight, humor, and company.

Fabrication and characterization of planar and channel polymer waveguides. II. Poly(p-phenylene benzobisthiazole) (PBZT) filmsDedicated to the memory of Bruce A. Reinhardt who is no longer with us in this world. Bruce was a loyal friend and a gifted chemist–we all miss his insight, humor, and company.

Optical properties of lissamine functionalized Nd 3+ complexes in polymer waveguides and solution

Lissamine functionalized terphenyl-based Nd complexes are synthesized, and incorporated in deuterated dimethylsulfoxide solutions and partially fluorinated planar polymer waveguides. Optical excitation of the lissamine sensitizer around 500 nm, followed by intramolecular energy transfer to the Nd 3+ ion, causes near-infrared photoluminescence (890, 1060, 1340 nm) due to intra-4f transitions in the Nd 3+ ion. The intramolecular energy transfer rate is larger than 10 7 s −1. Due to the large absorption cross-section of the sensitizer (>10 −17 cm 2 around 500 nm), the Nd 3+ is excited 10 4 times more efficiently than in a pure complex, without sensitizer. The Nd 3+ luminescence lifetime is relatively short, both in solution (2.2 μs) and in a polymer host (0.8 μs), which is attributed to coupling to vibrational states of nearby C–H and O–H groups. Spincoated fluorinated polymer planar waveguides, doped with these sensitized organic Nd complexes show excellent waveguide properties. Upon continued illumination, photodegradation is observed in the doped polymer films.

Measurement of the optical transmission modes and losses of the poled guest–host polymer NAEC/PEK-c planar waveguides

The polyetherketone (PEK-c) guest–host polymer planar waveguides doped with (4′-nitro)-3-azo-9-ethyl-carbazole (NAEC) were prepared. The waveguide films were poled by corona-onset poling at elevated temperature (COPET), and the corona poling setup includes a grid voltage making the surface-charge distribution uniform. By using the prism-in coupling method, the dark-line spectrum given by the reflected intensity versus the angle of incidence have been obtained, and the optical transmission losses of mth modes have been measured for the poled polymer waveguides at λ=632.8 nm. The measurement result showed that the optical loss of the fundamental mode is less than 0.7 dB cm −1 for the TE polarization.

Optical properties of erbium-doped organic polydentate cage complexes

The optical properties of different erbium (Er)-doped polydentate hemispherand organic cage complexes are studied, for use in polymer-based planar optical amplifiers. Room temperature photoluminescence at 1.54 μm is observed, due to an intra-4f transition in Er3+. The Er is directly excited into one of the 4f manifolds (at 488 nm), or indirectly (at 287 nm) via the aromatic part of the cage. The luminescence spectrum is 70 nm wide (full width at half maximum), the highest known for any Er-doped material, enabling high gain bandwidth for optical amplification. The absorption cross section at 1.54 μm is 1.1×10−20 cm2, higher than in most other Er-doped materials, which allows the attainment of high gain. Measurements were performed on complexes in KBr tablets, in which the complex is present in the form of small crystallites, or dissolved in the organic solvents dimethylformamide and butanol-OD. In KBr the luminescence lifetime at 1.54 μm is <0.5 μs, possibly due to concentration quenching effects. In butanol-OD solution, the lifetime is 0.8 μs, still well below the radiative lifetime of 4 ms estimated from the measured absorption cross sections. Experiments on the selective deuteration of the near-neighbor C–H bonds around the Er3+-ion indicate that these are not the major quenching sites of the Er3+ luminescence. Temperature dependent luminescence measurements indicate that temperature quenching is very small. It is therefore concluded that an alternative luminescence quenching mechanism takes place, presumably due to the presence of O–H groups on the Er-doped complex (originating either from the synthesis or from the solution). Finally a calculation is made of the gain performance of a planar polymer waveguide amplifier based on these Er complexes, resulting in a threshold pump power of 1.4 mW and a typical gain of 1.7 dB /cm.

Determination of the glass transition temperature of nonlinear optical planar polymer waveguides by attenuated total reflection spectroscopy

We present an experimental technique for nondestructive measurement of the glass transition temperature (Tg) of thin nonlinear optical (NLO) polymer films by attenuated total reflection spectroscopy. At Tg the thermal expansion coefficient and temperature dependence of the refractive index ∂n/∂T change discontinuously. This change can be detected with high sensitivity by recording thickness and refractive index of a polymer waveguide coated on a glass/gold substrate as a function of temperature. Measurements were made on various high Tg NLO polymers (Tg up to 170 °C). The resulting Tg values are compared with those determined by differential scanning calorimetry of the bulk material.

Experimental investigations and numerical simulations of spatial solitons in planar polymer waveguides

We investigated the beam propagation in a planar polymer waveguide. The conjugated polymer used in our experiments is a solution processable polyarylene-vinylene derivative, the DP-PPV/DP-PFV copolymer, which exhibits both a high focusing Kerr-like nonlinearity and an outstanding light and air stability. We report the first experimental observation of spatial solitons in a polymer waveguide. The corresponding spectral broadening could be detected. To obtain a deeper understanding of the experimental results we carried out numerical simulations of the spatial-temporal objects under investigation. The numerical simulations agree quite well with the experimental findings.