Andrew M. Weiner

Femtosecond pulse shaping using spatial light modulators

We review the field of femtosecond pulse shaping, in which Fourier synthesis methods are used to generate nearly arbitrarily shaped ultrafast optical wave forms according to user specification. An emphasis is placed on programmable pulse shaping methods based on the use of spatial light modulators. After outlining the fundamental principles of pulse shaping, we then present a detailed discussion of pulse shaping using several different types of spatial light modulators. Finally, new research directions in pulse shaping, and applications of pulse shaping to optical communications, biomedical optical imaging, high power laser amplifiers, quantum control, and laser-electron beam interactions are reviewed.

Coherent ultrashort light pulse code-division multiple access communication systems

A new technique for encoding and decoding of coherent ultrashort light pulses is analyzed. In particular, the temporal and statistical behavior of pseudonoise bursts generated by spectral phase coding of ultrashort optical pulses is discussed. the analysis is motivated by recent experiments that demonstrate high-resolution spectral phase coding of picosecond and femtosecond pulses and suggest the possibility of ultrahigh speed code-division multiple-access (CDMA) communications using this technique. The evolution of coherent ultrashort pulses into low intensity pseudonoise bursts as a function of the degree of phase coding is traced. The results are utilized to analyze the performance of a proposed CDMA optical communications system based upon encoding and decoding of ultrashort light pulses. The bit error rate (BER) is derived as a function of data rate, number of users, and receiver threshold, and the performance characteristics are discussed for a variety of system parameters. It is found that performance improves greatly with increasing code length. >

Femtosecond optical pulse shaping and processing

2.4. 2.5. 2.6. Pulse shaping by linear filtering Picosecond pulse shaping Fourier synthesis of femtosecond optical waveforms 2.3.1. Fixed masks fabricated using microlithography 2.3.2. Spatial light modulators (SLMs) for programmable pulse shaping 2.3.2.1. Pulse shaping using liquid crystal modulator arrays 2.3.2.2. Pulse shaping using acousto-optic deflectors 2.3.3. Movable and deformable mirrors for special purpose pulse shaping 2.3.4. Holographic masks 2.3.5. Amplification of spectrally dispersed broadband laser pulses Theoretical considerations Pulse shaping by phase-only filtering An alternate Fourier synthesis pulse shaping technique 3. Additional Pulse Shaping Methods 3.1. Additional passive pulse shaping techniques 3. I. 1. Pulse shaping using delay lines and interferometers 3.1.2. Pulse shaping using volume holography 3.1.3. Pulse shaping using integrated acousto-optic tunable filters 3.1.4. Atomic and molecular pulse shaping 3.2. Active Pulse Shaping Techniques 3.2.1. Non-linear optical gating 3.2.2. Pulse shaping by temporal stretching and modulation 3.2.3. Pulse shaping using electro-optic phase modulation 3.2.4. Pulse processing using time-domain lenses 3.2.5. Pulse synthesis using separate phase-locked laser oscillators 4. Holographic Processing of Ultrashort Pulses 4.1. Spectral holography 4.1. I. Principles of spectral holography for time-domain signal processing 4.1.2. Experimental studies of femtosecond spectral holography 4.1.2.1. Spectral holography of time-delayed pulses 4.1.2.2. Spectral holography of phase-modulated pulses 4.1.2.3. Matched filtering 4. I .2.4. Discussion 4. I .3. Space-to-time and time-to-space conversions using spectral holography 4.1.4. Nanosecond spectral holography 4.2. Time-domain holography 4.3. Pulse processing by spectral hole burning and photon echoes 4.4. Pulse processing by non-linear interactions of chirped pulses in optical fibers 5. Applications of Pulse Shaping 5.1. Pulse shaping in ultrafast non-linear fiber optics 5.1.1. Dark optical solitons 5.1.2. Complex solitons 5. I .3. Ultrafast all-optical switching 5.1.4. Fiber and grating pulse compression 5.2. Pulse shaping for optical communications networks 5.2.1. Pulse shaping for time-division multiplexing (TDM) 5.2.2. Pulse shaping for wavelength-division multiplexing (WDM) 5.2.3. Pulse shaping for code-division multiple-access (CDMA) 5.3. Pulse shaping for chirped pulse amplification

Programmable shaping of femtosecond optical pulses by use of 128-element liquid crystal phase modulator

Programmable shaping of femtosecond pulses by using a 128-element liquid crystal modulator to manipulate the phases of optical frequency components which are spatially dispersed within a grating-and-lens pulse shaping apparatus is described. This apparatus makes possible gray-level control of the spectral phases and allows modification of the pulse shape on a millisecond time scale under electronic control. Refinements in the design of the multielement modulator result in pulse shaping fidelity comparable to that which can be achieved with microlithographically fabricated masks. Several examples of pulse shaping operation, including pulse position modulation, programmable pulse compression, and adjustable cubic phase distortion, are described. >

Programmable femtosecond pulse shaping by use of a multielement liquid-crystal phase modulator.

We report programmable shaping of femtosecond optical pulses by use of a multielement liquid-crystal modulator to manipulate the phases of spatially dispersed optical frequency components. Our approach provides for continuously variable control of the optical phase and permits the pulse shape to be reconfigured on a millisecond time scale. We use the apparatus to demonstrate femtosecond pulse-position modulation as well as programmable compression of chirped femtosecond pulses.

Observation of spatial optical solitons in a nonlinear glass waveguide

We report the observation of spatial optical solitons due to the Kerr nonlinearity in a planar glass waveguide and present measurements of the nonlinear response obtained by placing a pinhole at the output of the waveguide. For input intensities greater than that required for the fundamental soliton, we observe breakup of the output owing to the effect of two-photon absorption.

An All-Silicon Passive Optical Diode

A Passive Optical Diode Electrical diodes are at the core of microelectronics. The optical equivalent, however, has been difficult to realize owing to the time-reversal symmetry of Maxwells equations that describe electromagnetic propagation. Usually, a control input in the form of a magnetic field is required that breaks that symmetry. Such inputs are not practical for optical integrated circuits. Fan et al. (p. 447, published online 22 December) developed a silicon-based microresonator device that could control the asymmetric transmission of light through it. The passive optical diode was compatible with current complementary metal-oxide semiconductor processing technology and thus should be readily integrated into optoelectronic circuitry. A silicon-based device is developed that allows the asymmetric propagation of light. A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing.

Spectral line-by-line pulse shaping of an on-chip microresonator frequency comb

We report spectral phase characterization and optical arbitrary waveform generation of on-chip microresonator combs. Random relative frequency shifts due to uncorrelated variations of frequency dependent phase are at or below the 100 μHz level.

Encoding and decoding of femtosecond pulses

We demonstrate the spreading of femtosecond optical pulses into picosecond-duration pseudonoise bursts. Spreading is accomplished by encoding pseudorandom binary phase codes onto the optical frequency spectrum. Subsequent decoding of the spectral phases restores the original pulse. We propose that frequency-domain encoding and decoding of coherent ultrashort pulses could form the basis for a rapidly reconfigurable, code-division multiple-access optical telecommunications network.

Femotosecond switching in a dual-core-fiber nonlinear coupler

We report all-optical switching of 100-fsec pulses in a fused-quartz dual-core-fiber directional coupler. The length of the device is 0.5 cm, and the switching power is 32 kW. Pulses are routed to either of two separate fiber guides, depending on the input power. Measurements of pulse reshaping by the nonlinear coupler provide compelling evidence of the devices ability to response on a femotosecond time scale.