Peter Kopka

Bistable micromechanical fiber-optic switches on silicon with thermal actuators

Abstract A new bistable moving-fiber switch for applications in optical communication systems is developed by employing advanced bulk silicon micromachining. The bistable switch utilizes actuators based on thermal expansion and the bimetal effect. Switches and switch arrays are successfully fabricated and tested. Due to the low number of process steps and the high yield and reliability, the process technology is suitable for low-cost single- and multi-mode fiber optic switches. A typical fiber-to-fiber insertion loss of 2±0.5 dB (single-mode fibers at 1300 nm wavelength, including MT-connector losses of typically 0.5–1.5 dB) is achieved in an array of 12 switches. The cross talk is below the detection limit (

All-silicon bistable micromechanical fiber switch based on advanced bulk micromachining

Bulk silicon micromachining is used to fabricate bistable optical fiber switches. The switches are based on a silicon device consisting of an actuator for fiber movement and a V-groove fiber clamp for bistable operation. The complete mechanical structures including thermal actuators are etched into standard silicon wafers using anisotropic wet etching in KOH. While switching is caused by asymmetric thermal expansion of a U-shaped silicon cantilever, the fiber clamp is driven by the bimaterial effect. The efficient process technology allows a low cost batch fabrication of these devices. The switches exhibit an insertion loss <1 dB and a crosstalk of <-60 dB using standard single-mode fibers. A switching power below 1 W is required during switching.

Low-loss fiber-matched low-temperature PECVD waveguides with small-core dimensions for optical communication systems

Plasma-enhanced chemical vapor deposition (PECVD) offers a simple way of fabricating (doped) silica layers on silicon. A new design of the waveguide core allows low-loss fiber matched waveguides with low birefringence without high-temperature annealing. The increased loss of doped plasma deposited silica due to hydrogen incorporation is overcome by reducing the core dimensions and increasing the refractive index contrast. The waveguides can easily be fabricated using standard PECVD technologies and resist masked reactive ion etching (RIE) etching. Integrated optical devices such as 1/spl times/8 power splitters, 1300/1550-nm wavelength multiplexers and thermooptical switches were successfully fabricated and tested.

Thermooptical digital switch arrays in silica-on-silicon with defined zero-voltage state

Arrays of thermooptical digital switches for 1300 nm wavelength have been fabricated employing PECVD silica on silicon technology. The switches are based on mode sorting in asymmetric waveguide branches. An asymmetric layout of the waveguide branch/crossing leads to a defined zero-voltage state which is useful for protection switching in optical SDM-networks. The power consumption is reduced by heat flow optimization using silica and silicon microstructuring. The switch arrays are coupled to fiber ribbons.

Optical fibre switches based on full wafer silicon micromachining

An optical (1 × 2) moving-fibre switch with bistable operation is presented. The low cost fabrication process based on bulk anisotropic Si etching for thermal actuators with cross sections of 80 × 150 µm2 is described. V-grooves are used for a precise alignment of the optical fibres. Switches and switch arrays are fabricated with high yield and high mechanical stability. An insertion loss of 2 dB including MT-connector losses and a cross talk below the detection limit (-60 dB) are measured. The thermally driven actuators operate with a power <700 mW which is, due to the bistable operation, needed for 100 ms only.

Lensless latching-type fiber switches using silicon micromachined actuators

Thermally driven latching-type moving-fiber switches without lenses are presented. Silicon micromachined 1/spl times/2, 1/spl times/4 and arrays of 1/spl times/2 switches with high reliability show insertion losses below 1 dB and below /spl sim/60 dB crosstalk.

Bistable micromechanical fiber-optic switches on silicon

The fiber-optical switch is based on silicon micromachining and standard single- or multimode fibers. It combines the low cross talk level (<-60 dB) of fiber-optical switches with the easy-to-handle fabrication techniques of silicon micromachining. The basic concept is the movement of an input fiber between two V-grooves containing the output fibers. A bistable operation is achieved by a fiber clamp.

Micromechanical fiber switch arrays on silicon

Bistable micromechanical(1/spl times/2) and (1/spl times/4) fibre switches with insertion loss <1 dB and cross talk <-60 dB have been developed. Switches and switch arrays can be batch fabricated with standard semiconductor technologies on [100] or [110] silicon.

Latching-type 2x2 and 1x4 fiber-optic switches

The presented latching-type 2 by 2 and 1 by 4 fiber-optic switches are based on full wafer micromachining of silicon wafers using anisotropic wet etching in KOH. Bulk micromachining allows the low-cost batch fabrication of structures with very high precision suitable for fiber alignment. The optical fiber switches consist of two thermally driven silicon actuators, a coupled U-shaped cantilever via thin flexible silicon beams and a stiff platform prevents angular displacement of the fibers. Switches have been fabricated with high yield, high mechanical stability, and good optical properties. Using standard single- mode fibers, the switches exhibit a crosstalk of < - 60 dB. Insertion losses below 1 dB and about 1 dB are achievable for 1 by 4 and 2 by 2 switches, respectively. A power below 0.6 W and 1.0 W for the 2 by 2 and 1 by 4 micromechanical fiber switch is needed during the switching time. Bistable 1 by 2 optical fiber switches have been tested for more than 1 X 106 switching cycles without any failure and after more than one year at room conditions they do not show any degeneration of optical properties and switching behavior.