Modulated semiconductor DFB laser array with a MEMS-based RF switch
View Patent ↗Many approaches to tunable lasers use an array of DFBs, where each element of the array has a different wavelength. In some operations one element of the array is activated at a time depending on the desired wavelength. For modulated applications, an RF voltage is applied to a specific element of the DFB array, generally using an RF switch. In standard configurations, the demands on the switch are relatively difficult, generally requiring low RF insertion loss and good high frequency performance to 10 GHz. The DFB arrays are generally common cathode or common anode, depending on the type of the substrate used to fabricate the devices. Described herein is an array with a common cathode or anode configuration using a MEMS based switch that shorts the selected laser to RF ground. With this topology, preferably the off-state capacitance should be low with the MEMS switch.
1. A directly modulated laser array with a microelectromechanical switch, comprising:
a laser array on a substrate; and
a micromechanical switch for allowing provision of an activation signal to a selected laser of the laser array, wherein lasers of the laser array share a common cathode, the microelectromechanical switch is configured to selectively couple both a DC signal source and an RF ground to an anode of the selected laser.
2. The directly modulated laser array with microelectromechanical switch of claim 1 wherein the laser array on a substrate is on a first chip and the microelectromechanical switch is on a second chip, and the first chip and the second chip are flip chipped together.
3. The directly modulated laser array with microelectromechanical switch of claim 1 further comprising a termination resistance approximate the RF ground.