Deep proton writing: a rapid prototyping polymer micro-fabrication tool for micro-optical modules

One of the important challenges to deploying the emerging breed of nanotechnology components is interfacing them with the external world, preferably accomplished with low-cost micro-optical devices. In our labs at the Vrije Universiteit Brussel (VUB), we are therefore focusing on the continuous development of a rapid prototyping technology for the fabrication of micro-optical modules. In this technology, which we call deep proton writing (DPW), we bombard polymer samples with swift protons, which will result after chemical processing steps in high quality micro-optical components. The strength of the DPW micro-machining technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. The DPW technology is furthermore compatible with low-cost mass-replication techniques such as micro-injection moulding and hot embossing. In this paper we give an overview of the process steps of the technology and the characteristic qualities we can expect from the components made by DPW. The general overview of the technology is followed by three case studies of different micro-optical components that were fabricated at our labs: (i) two-dimensional fibre connectors, (ii) out-of-plane couplers for optical waveguides embedded in printed circuit boards (PCBs), (iii) intra multi-chip-module (MCM) level optical interconnection via free space optical modules.

[1]  H. Bethe.  Zur Theorie des Durchgangs schneller Korpuskularstrahlen durch Materie , 1930 .

[2]  U. Fano,et al.  Penetration of protons, alpha particles, and mesons , 1963 .

[3]  M. Jacobs.  The structure of the metastable precipitates formed during ageing of an Al-Mg-Si alloy , 1972 .

[4]  James F. Ziegler,et al.  Handbook of Stopping Cross-Sections for Energetic Ions in All Elements , 1980 .

[5]  F. Komarov,et al.  Energy loss and ion ranges in solids , 1981 .

[6]  D. Hess,et al.  Transport models for swelling and dissolution of thin polymer films , 1989 .

[7]  Steven A. Orszag,et al.  Turbulence: Challenges for Theory and Experiment , 1990 .

[8]  John Melngailis,et al.  Focused ion beam lithography , 1991 .

[9]  S. Mihailov,et al.  Fabrication of refractive microlens arrays by excimer laser ablation of amorphous Teflon. , 1993, Applied optics.

[10]  Henry White,et al.  Fabrication of two-dimensional fiber optic arrays for an optical crossbar switch , 1994 .

[11]  P. McNally,et al.  A comparative study of Pd/Sn/Au, Au/Ge/Au/Ni/Au, Au-Ge/Ni and Ni/Au-Ge/Ni ohmic contacts to n-GaAs , 1998 .

[12]  Wolfgang Ehrfeld,et al.  Injection-moulded fibre ribbon connectors for parallel optical links fabricated by the LIGA technique , 1998 .

[13]  L. Mansur,et al.  LET effect on cross-linking and scission mechanisms of PMMA during irradiation , 1999 .

[14]  Cheng Sun,et al.  Micro-stereolithography of polymeric and ceramic microstructures , 1999 .

[15]  Christophe Vieu,et al.  Electron beam lithography: resolution limits and applications , 2000 .

[16]  D.A.B. Miller,et al.  Rationale and challenges for optical interconnects to electronic chips , 2000, Proceedings of the IEEE.

[17]  Guiyun Kai,et al.  Bidirectional grating wavelength shifter with a broad-range tunability by using a beam of uniform strength , 2001 .

[18]  R.T. Chen,et al.  Optoelectronic integration of polymer waveguide array and metal-semiconductor-metal photodetector through micromirror couplers , 2001, IEEE Photonics Technology Letters.

[19]  John A. Rogers.  Rubber stamping for plastic electronics and fiber optics , 2001 .

[20]  G. Whitesides,et al.  Fabrication of Three-Dimensional Microfluidic Systems by Soft Lithography , 2001 .

[21]  Y Chen,et al.  Nanofabrication: Conventional and nonconventional methods , 2001, Electrophoresis.

[22]  C. M. Sotomayor Torres,et al.  Nanoimprint lithography: challenges and prospects , 2001 .

[23]  Hugo Thienpont,et al.  Alignment features for micro-optical interconnect modules , 2003 .

[24]  John A. Rogers,et al.  Tunable optical fiber devices based on broadband long-period gratings and pumped microfluidics , 2003 .

[25]  C. Nuzman,et al.  1100 x 1100 port MEMS-based optical crossconnect with 4-dB maximum loss , 2003, IEEE Photonics Technology Letters.

[26]  L. Cosentino,et al.  Beam monitoring enhances Deep Proton Lithography : towards high-quality micro-optical components 298 , 2003 .

[27]  Christof Debaes,et al.  Low-cost microoptical modules for MCM level optical interconnections , 2003 .

[28]  Takayuki Ando,et al.  Super Low-Loss, Super High-Density Multi-Fiber Optical Connectors , 2003 .

[29]  H. Thienpont,et al.  MT-compatible laser-ablated interconnections for optical printed circuit boards , 2004, Journal of Lightwave Technology.

[30]  M. Heckele,et al.  Review on micro molding of thermoplastic polymers , 2004 .

[31]  Hugo Thienpont,et al.  Plastic Microlens Arrays by Deep Lithography with Protons: Fabrication and Characterization , 2004 .

[32]  Hugo Thienpont,et al.  Real-time in situ sag characterization of microlenses fabricated with Deep Lithography with Protons , 2005, SPIE Optical Metrology.

[33]  C. Debaes,et al.  High-precision 2-D SM fiber connectors fabricated through deep proton writing , 2006, IEEE Photonics Technology Letters.

[34]  M. Vervaeke,et al.  Optomechanical Monte Carlo Tolerancing Study of a Packaged Free-Space Intra-MCM Optical Interconnect System , 2006, IEEE Journal of Selected Topics in Quantum Electronics.

[35]  Christof Debaes,et al.  Prototyping micro-optical components with integrated out-of-plane coupling structures using deep lithography with protons , 2006, SPIE Photonics Europe.

[36]  Hans Peter Herzig,et al.  Comparing glass and plastic refractive microlenses fabricated with different technologies , 2006 .