USA As Represented by Secretary of the Navy

Thomas F Carruthers

Irl N Duling, Iii

Janet W Lou

Henry F Taylor

Marc Currie

Joseph F Weller

Michael L Dennis

Thomas S Clark

An electro-optic clock recovery circuit comprising an electro-optic modulator circuit operatively coupled to; a photodetector circuit; a buffer circuit operatively coupled to said photodetector circuit; a voltage controlled oscillator operatively coupled to said buffer circuit and to said electro-optic modulator circuit; wherein the electro-optic modulator circuit receives and modulates a multi-channel input data stream, the photodetector circuit responsive to the modulated input data stream drives the voltage controlled oscillator in a phase locked loop through the buffer circuit, and the modulator circuit is responsive to the voltage controlled oscillator and is driven at a harmonic of the voltage controlled oscillator. A method for the recovery of a single channel clock rate from a optical time division multiplexed data stream whose data rate is a multiple of the base rate comprising the steps of: modulating a multi-channel data stream with an electro-optic modulator circuit, detecting the modulated data steam with a photodetector circuit, controlling the frequency of a voltage controlled oscillator with the voltage associated with the photodetector circuit; driving the electro-optic modulator circuit with the output of the voltage controlled oscillator wherein the transmission window of the electro-optic modulator is toggled at a harmonic of the frequency of said voltage controlled oscillator.

High speed electro-optic clock recovery circuit

The ultrashort fiber laser with a dispersion-managed cavity. The laser is an actively mode-locked sigma laser, typically locked at a repetition rate of 10 GHz, driven by an external frequency source and actively length stabilized, and nearly 10,000 pulses circulate within the laser cavity. A Mach-Zehnder modulator is placed in a loop of polarization-maintaining (PM) fiber. The polarization state of light injected into the non-PM branch evolves in a random manner but is transformed into an orthogonal state by a Faraday mirror; linearly polarized light injected into the branch by a polarizing beamsplitter returns to the beamsplitter also linearly polarized but rotated by 90&#xb0;. The cavity of the laser is composed of several fibers. The average dispersion Dis anomalous and is approximately equal to 0.1 ps/(nm&#xb7;km).

Ultrashort-pulse fiber laser with a dispersion-managed cavity

A multiple wavelength laser apparatus is taught to select wavelengths for simultaneous generation of short pulses at multiple wavelengths having application in wavelength-division-multiplexed communications systems, photonic microwave systems, and pump-probe applications. The multiple wavelength laser comprises an optical fiber lasing material, a laser pump source connected to said lasing material for outputting coherent light, a splitter for dividing said coherent light into parallel paths of differing wavelengths, parallel band pass filters for selecting multiple wavelengths, and parallel Faraday mirrors for operating the multiple wavelength laser in a single polarization state.

Multiple wavelength pulsed source

An optical fiber laser source comprising a polarization-maintaining loop and a birefringence-compensating branch preferably operatively connected to a length-stabilizing element is disclosed. The optical fiber laser source provides soliton pulse compression to reduce the duration of the pulses of the output pulse train to 1.3 ps or less.

Actively mode-locked, single-polarization, picosecond optical fiber laser

A pulsed laser includes a polarization section having a port, the polarization section being for receiving light at the port in a selected state of polarization and for outputting light at the port having a state of polarization orthogonal to the selected state of polarization. The laser also includes an amplifying section having a port, a bidirectional amplifier, and a rotator-reflector, the amplifying section being for receiving light at the amplifying section port and for outputting light at the amplifying section port amplified with respect thereto, the bidirectional amplifier being operatively coupled to the amplifying section port at a first end and operatively coupled to the rotator-reflector at a second end. The pulsed laser further includes means for transmitting light in both directions between the polarization section port and the amplifying section port, an amplitude modulator responsive to a modulation signal for actively mode-locking light internal to the pulsed laser, and means responsive to light internal to the polarization section for outputting coherent light.

Polarization-stable pulsed laser

A semiconductor photodetector employs a multilayer structure for controlling speed, efficiency and noise. A light-absorbing low band gap semiconductor emitter layer produces photogenerated charge upon absorption of light. A semiconductor collector layer collects the photogenerated charge. A semiconductor barrier layer between the light absorbing layer and the collector layer selectively blocks substantially all but photogenerated charge. A base layer may be optionally employed between the barrier layer and the collector layer for gating the current flow and controlling wavelength sensitivity.

Semiconductor photodetector device

An antiresonant nonlinear mirror to replace one mirror of a laser for passive modelocking of the laser, the antiresonant nonlinear mirror comprising: a beam splitter for coupling the mirror to a laser cavity; a mirror arrangement for defining an optical ring with the beam splitter in which two light beams produced by the beam splitter in response to a light beam from the laser cavity can counterpropagate around the ring; an intensity dependent anisotropic nonlinear element disposed within the ring; and a polarization sensitive element disposed within the ring for adjusting the birefringence thereof to produce spontaneous modelocking in the coupled laser cavity.

Antiresonant nonlinear mirror for passive laser modelocking

Transferred-electron device (TED) microwave burst and single pulse generators which are triggered by picosecond optical pulses. The burst generator includes a TED having a cathode, an anode, and a gate electrode positioned therebetween, all located on a semiconductor substrate. An optical pulse applied to the substrate between the gate and anode electrodes causes a plurality of space charge domains to sequentially travel from the gate to the illuminated region thereby causing an oscillatory burst of current to occur in the external leads of the TED. The frequency of the burst is proportional to the distance between the gate and the illuminated region and the burst duration is proportional to the optical pulse amplitude and/or duration. Alternatively, the burst generators may be formed from a two terminal TED with the cathode electrode being treated as the gate. A single pulse generator may be formed by applying an optical pulse to the substrate between the cathode and the gate of a three terminal TED. The duration of the single pulse is proportional to the distance between the gate and the anode.

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Laurel, MD, United States of America

Thomas F Carruthers