Wave-plate structures, power selective optical filter devices, and optical systems using same

DWPI Title: Wave plate structure of power selective optical filter device of optical system, has fast axis of entry wave plate which is oriented perpendicular to fast axis of exit wave plate
Abstract: In an embodiment, an optical filter device includes an input polarizer for selectively transmitting an input signal. The device includes a wave-plate structure positioned to receive the input signal, which includes first and second substantially zero-order, zero-wave plates arranged in series with and oriented at an angle relative to each other. The first and second zero-wave plates are configured to alter a polarization state of the input signal passing in a manner that depends on the power of the input signal. Each zero-wave plate includes an entry and exit wave plate each having a fast axis, with the fast axes oriented substantially perpendicular to each other. Each entry wave plate is oriented relative to a transmission axis of the input polarizer at a respective angle. An output polarizer is positioned to receive a signal output from the wave-plate structure and selectively transmits the signal based on the polarization state.
Use: Wave plate structure of power selective optical filter device such as optical switch structure and optical limiter structure of optical system (both claimed).
Advantage: The optical filter device can be used to partially block amplified spontaneous emission (ASE) generated by one optical fiber amplifier to another optical fiber amplifier and vice versa. The bidirectional blocking of ASE can enable both fiber amplifiers to be operated at very high small-signal gain. The optical switch structure can reduce or eliminate multi-stage amplification of ASE and/or multi-stage parasitic lasing. The optical switch structure can prevent damage to fiber amplifier or optical components by regulating the amplitude of the amplified pulse transmitted through the optical switch structure. The optical switch structures can be used in conjunction with fiber amplifiers to create a wide variety of multi-stage fiber amplifier systems. The optical switch structure can have no effect on the amplitude of the transmitted pulse when the amplitude modulator is in transmitting state. Thus, the optical switch structure can allow the extinction ratio of the amplitude modulator to be increased without any significant insertion loss penalty. The optical filter devices can be used to optically isolate a pulsed laser source and alter the temporal shape of one or more laser pulses. The filter device can improve the extinction ratio of an active optical switching device and another passive optical switching device. The filter device can be used in a continuous wave laser cavity to reduce relative intensity noise, prevent or suppress amplitude fluctuations and used to limit the amplitude of an optical signal undergoing amplification to prevent the amplified signal from exceeding the damage threshold of one or more active and/or passive optical components. The filter device can be used for optical switching of one or more input signals by one or more control signals. The filter device can be used in a laser cavity to assist passively mode-locked operation and to assist actively mode-locked operation. The filter device can be used in a laser cavity to affect laser cavity dumping.
Novelty: The structure has zero-order, zero-wave plates arranged in series with and oriented at an angle relative to each other. The zero-wave plates are configured to alter polarization state of input signal passing that depends on power of input signal. Each zero-wave plate includes entry and exit wave plate each having fast axis oriented perpendicular to each other. The slow axis of exit wave plate of one zero-order, zero-wave plate is oriented at about 40° to about 50° relative to slow axis of entry wave plate of another zero-order, zero-wave plate.
Filed: 4/26/2010
Application Number: US2010767327A
Tech ID: SD 11361.1
This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention.
Data from Derwent World Patents Index, provided by Clarivate
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