Single-mode Polymer Waveguides Research Articles

광섬유 수동정렬을 위한 단일 모드 대형 코어 폴리머 광도파로

정력 오차 허용 범위를 증가 시켜서 효과적인 수동정렬이 가능토록 하기 위한 단일 모드 대형 코어 폴리머 광도파로를 구현하였다. 대형 코어 광도파로는 TEC(thermally expanded core) 광섬유의 모드와 일치하는 큰 도파모드를 가진다. 이로 인해 광섬유와 도파로의 정렬오차로 인한 모드 결합 손실을 줄일 수 있게 된다. 코어와 클래딩의 굴절률 차이가 5 <TEX>${\times}$</TEX> <TEX>$10^{-4}$</TEX> 인 폴리머 재료를 이용하여 25 <TEX>${\times}$</TEX> 25 <TEX>$\mu\textrm{m}$</TEX><TEX>$^2$</TEX> 크기의 정사각형 광도파로를 제작하였으며 도파모드 관측결과 단일모드로 동작함을 확인하였다. 이와 같이 두꺼운 형태의 광도파로 구조 제작을 위하여 자외선 경화를 이용한 인젝션 몰딩(injection molding) 공정을 사용하였다. 제작된 광도파로 소자를 TEC 광섬유와 정렬연결을 할 때 정렬오차가 4.5 <TEX>$\mu\textrm{m}$</TEX> 까지 증가하더라도 삽입손실 증가는 0.5 dB 이하고 유지됨을 확인하였다. To increase the tolerance for passive fiber alignment, a single mode polymer waveguide with a large core structure is demonstrated. The large core waveguide is designed to have a mode profile comparable to that of a thermally expanded core (TEC) fiber, and it can be connected to a high-contrast waveguide through an adiabatic transition taper structure. From a waveguide with a rectangular core of 25 <TEX>${\times}$</TEX> 25 <TEX>${\mu}{\textrm}{m}$</TEX><TEX>$^2$</TEX>, a single mode propagation is observed when the index contrast is as low as 0.0005. A UV-cured injection molding method is used to fabricate the thick core structure. Due to the large mode size, the insertion loss of the device is below 0.5 dB until the lateral displacement of the TEC fiber is 4.5 <TEX>${\mu}{\textrm}{m}$</TEX>. The low insertion loss is important for reproducible passive alignment.

Fabrication of large-core single-mode polymer waveguide connecting to a thermally expanded core fiber for increased alignment tolerance

To increase the fiber alignment tolerance for the passive alignment with a high-contrast waveguide, a single-mode polymer waveguide with a large core structure is proposed. The large core waveguide is designed to have a mode profile comparable to that of a thermally expanded core (TEC) fiber, and it can be connected to a high-contrast waveguide through an adiabatic transition taper structure. From a waveguide with a rectangular core of 25×25 μm2, a single-mode propagation is observed when the index contrast is as low as 0.0005. A UV-cured injection molding method is used to fabricate the thick core structure. Due to the large mode size, the insertion loss of the device is below 0.5 dB until the lateral displacement of the TEC fiber is 4.5 μm, that is important for reproducible passive alignment.

Direct measurement of proton-beam-written polymer optical waveguide sidewall morphorlogy using an atomic force microscope

Proton-beam writing (PBW) is a direct-write micromachining technique capable of fabricating low-loss single-mode polymer waveguides with straight and smooth sidewalls. Recently, the sidewall morphologies of such proton beam written polymer waveguide structures were directly measured using an atomic force microscope (AFM). Statistical information such as the rms roughness and the correlation length of the sidewall profile obtained from the AFM scans allows us to quantify the quality of the sidewalls and optimize the fabrication parameters using PBW. For structures fabricated using a stage scanning speed of ∼10μm∕s, a rms roughness of 3.8±0.3nm with a correlation length of 46±6nm was measured.

Singlemode optical waveguides using a high temperaturestable poylmer with low losses in the 1.55 µm range

Singlemode polymer waveguides are fabricated using a novel high temperature stable fluorinated polymer. Waveguide losses of <0.25 dB/cm were achieved both at 1300 nm as well as in the entire range from 1515 to 1565 nm.

Singlemode polymer waveguides for optical backplanes

Singlemode polymer waveguides with integrated mirrors for applications in optical bus systems are realised. The waveguide and mirror structures are fabricated in PMMA substrates by injection moulding. The microstructured metal mould inserts are prepared by silicon micromachining and electroplating. PFPMA/TeCEA is used as a UV-curing waveguide core copolymer. Devices with a waveguide attenuation of 0.21 dB/cm at 1300 nm and minor losses of /spl sim/1 dB have been demonstrated.

Design concept for singlemode polymer waveguides

A novel waveguide concept is presented, which is applicable to a multitude of optical polymers. It allows for singlemode single polymer waveguides with large cross-sections, despite considerable index differences between core and cladding layers. Results of waveguides fabricated from a commercially available, high temperature stable polymer ( Tg &gt; 350°C) are presented, indicating losses of below 0.5 dB/cm at 1.3 µm.

Fabrication of low loss polymer waveguides using injection moulding technology

Singlemode polymer waveguides with low transmission loss at 1300 nm are fabricated by using injection moulding as low cost mass replication technology for the fabrication of polymer waveguide substrates. The waveguide pattern is incorporated in the substrates in the form of grooves which are filled by fully deuterated EGDMA. First buried singlemode waveguides have been realised with a transmission loss as low as 0.3 dB/cm at 1300nm.

Single-mode polymer waveguide modulator

We report herein the first single-mode polymer waveguide modulator which can be formed on any surface regardless of its conductivity and refractive index. These include semiconductor, conductor, and insulator surfaces. The tunability of the refractive index of the polymer film allows us to shift the guiding layer from a stepped index profile to a graded index profile. The phase-matching condition for optical power transfer is achieved through current-induced index modulation. Thirty-six dB extinction ratio, which includes 3 dB absorption loss and 33 dB phase-matched cross coupling, was observed with a current injection density of ∼1.8 μA/μm2. Unlike the conventional symmetrical dual channel coupler, the disparity of the collinear waveguide pair provides us with a much larger dynamic range of waveguide dimension suitable for generating the required phase-matching condition and thus easing the requirement of waveguide fabrication.