11 th International Conference on Indium Phosphide and Related Materials 16-20 May 1999 Davos, Switzerland zyxwvutsr TuA3-4 TUNABLE INP/AIR GAP FABRY PEROT FILTER FOR WAVELENGTH DIVISION MULTIPLEX FIBER OPTICAL TRANSMISSION J. Daleiden”), N. Chitica”),M. Strassner”), A. Spisserb),J.L. Leclercqb), P. Viktorovitchb), D. Rondic’, E. Goutainc)J. Peerlings“), J. Pfeiffer”’, R. Riemenschneider”), K. Hjort”’ a) Royal Institute of Technology, Dept. of Electronics, Electrum 229, S-16440 Kista, Sweden b’Ecole Centrale de Lyon, LEAME, BP 163, F-69131 Ecully Cedex, France zyxwv dl Institut fur Hochfrequenztechnik, Techn. Universitat Darmstadt, D-64283 Darmstadt, Germany zyxw e) Uppsala University, Dept. of Materials Science, Box 534, S-75121 Uppsala, Sweden phone: +46 8 7521 190, fax: +46 8 7521240, email: daleiden@ele.kth.se Thomson-CSF LCR, Domaine de Corbeville, F-91404 Orsay Cedex, France Abstract An InP-based widely tunable and highly selective surface micromachined Fabry Perot filter for zyxwvutsr h= 1.55 pm is demonstrated. We present for the first time transmission measurements in a fiber-to-fiber setup and show that the devices are compatible with the demands of WDM optical fiber transmission. The full width at half maximum of the device is approximately 0.4 nm with an insertion loss of -3dB. The crosstalk to a 1.6 nm spaced channel is -20dB. The entire tuning range is 62 nm for an actuation voltage of 14 V whereas the FWHM is kept below 1 nm over a 40 nm tuning range. 1 Introduction Optical fiber communication using wavelength division multiplexing (WDM) has been extensively investigated in order to enable ultra high capacity transmission [ l ] zyxwvutsrqp . Dense WDM systems for long haul telecommunication links require closely spaced channels of 1.6nm, 0.8nm, or even 0.4 nm. An important limitation to those systems is the receiving end. Micro-opto-electro-mechanical structures (MOEMS) such as continuously tunable and highly selective Fabry Perot filters are very promising devices in terms of flexibility (wavelength tracking), monolithic integration, polarization insensitivity, and potential cost-effectiveness. Several reports on GaAs-based MOEMS like tunable filters, detectors, light emitting diodes (LED) and vertical cavity surface emitting lasers (VCSEL) have been previously presented [2], [3], [4], [5]. For long distance telecommunication fiber links the wavelength bands 1300 nm and 1550 nm are in use. High performance photodetectors for this wavelength range are based on the InGaAsP/InP material system. Thus InP-based MOEMS are of high interest because they could be monolithically integrated with these photodetectors. So far there are only a few publications in this field [6], [7], [SI, [9]. In the present work we report on an InP-based widely tunable and highly selective surface micromachined Fabry Perot filter for h=1.55 pm. The vertical air gap cavity is defined between two high reflectivity distributed Bragg reflectors (DBR). Continuous tuning is achieved by electrostatic actuation of the suspended InP-layers. We present for the first time transmission measurements in a fiber-to-fiber setup and show that the devices are compatible with the demands of WDM optical fiber transmission. I1 Design and Fabrication The filter consists of an air gap cavity defined between two high reflectivity InP / air gap DBRs. By the reason of the high refractive index contrast between InP and air (=3:1) extremely high reflectivity values and large reflectivity bandwidth are achieved. For our design a zy 0-7803-5562-8/99/$10.00 01 999 IEEE 285