Johan P. Burger

Noncollinear four-wave mixing in a broad area semiconductor optical amplifier

A high-efficiency noncollinear four-wave mixing in a broad area traveling-wave semiconductor optical amplifier is demonstrated. A key feature of the demonstrated configuration is the ability to isolate generated sidebands from the inputs. A wave-mixing efficiency of +8.2 dB with 22.6 dB of sideband isolation at 6° separation between the two pump beams was obtained. The dependence of the efficiency on pump detuning, separation angle, and probe wavelength was also investigated. Use of a high quality traveling-wave amplifier enabled us to achieve ripple-free broadband operation over 37 nm. The demonstrated configuration is a key to practical implementations of four-wave mixing based devices.

AMBIPOLAR DIFFUSION COEFFICIENT AND CARRIER LIFETIME IN A COMPRESSIVELY STRAINED INGAASP MULTIPLE QUANTUM WELL DEVICE

By using the technique of noncollinear nearly-degenerate four-wave mixing, ambipolar diffusion coefficients and carrier lifetimes were directly determined for a compressively-strained InGaAsP multiple quantum well semiconductor optical amplifier operating at 1.3 μm. A diffusion coefficient of 8.0 cm2/s and a carrier lifetime of 1.33 ns, were obtained at the amplifier current density of 1.88 kA/cm2. The current-density dependent measurements show that the diffusion coefficient will drop with increasing amplifier pumping current, which is consistent with the prediction of the conventional semiconductor theory.

A novel all-optical switch: the wavelength recognizing switch

A new class of an all-optical switch-the wavelength recognizing switch is proposed and experimentally demonstrated. The device uses a control signal to sense the wavelength of the input packet and taps a portion of the data packet to the appropriate output port. The device is based on noncollinear four-wave mixing in a broad-area traveling-wave semiconductor optical amplifier. Measured switching efficiency is +8.2 dB with -28.8 dB of crosstalk. The recognition bandwidth is as narrow as 0.03 /spl Aring/ and the 3-dB switching bandwidth is 42 nm.

Kerr-like nonlinear mode converters for integrated optic device applications

An integrated optic structure is proposed in order to make Kerr-like nonlinear interactions practical for optical signal processing applications. The interacting electric fields propagates as different modes of a multimode waveguide, and couple to each other or cause a nonlinear cross-gain or cross-phase modulation through the nonlinear dielectric permittivity perturbation caused by the propagating fields. Integrated optic mode combiners/mode splitters provide a way to spatially separate/combine the interacting fields, negating the need for spectral filtering in nonlinear interactions like four-wave mixing. This concept is applicable to all types of Kerr-like materials, but is particularly attractive for realizing novel devices, based on the large carrier nonlinearities in semiconductors.

The energy-limiting characteristics of a polarization-maintaining Sagnac interferometer with an intraloop compressively strained quantum-well saturable absorber

An experimental demonstration of an energy limiter for short pulses at 1550 nm is reported. The limiter is based on an optical fiber Sagnac loop with an intraloop dichroic saturable absorber based on an InGaAsP-based waveguide with compressively strained multiple quantum wells. The saturable absorber is placed asymmetrically in the loop and is used as a Kerr-like nonlinear phase shifter. The device is operated in a novel dual polarization scheme, which offers some unique advantages. Excellent limiting for noise reduction purposes is demonstrated with the device.

Nonlinear optics in a dual moded waveguide semiconductor optical amplifier

We have completed an extensive simulation study of four wave mixing (FWM) and two wave mixing (TWM) in a dual moded semiconductor optical amplifier (SOA). We have also completed beam propagation studies of the device with adiabatic mode sorters and have developed a practical fabrication approach to building a device which requires one regrowth step.

An optical filter based on carrier nonlinearities for optical RF channelizing and spectrum analysis

We experimentally demonstrate filtering based on the finite time response of the interband carrier nonlinearities in a direct bandgap semiconductor. The filter is implemented in a mixed strain polarization insensitive multiple-quantum-well, broad-area semiconductor amplifier. The key to the filter implementation is the separation of a four-wave mixing generated sideband from the linearly amplified inputs based on spatial filtering. Both spectrum analysis and channelizing of RF modulated optical carriers are demonstrated.

A tunable optical domain microwave filter suitable for wideband channelizing

We present the experimental demonstration of a novel narrowband optical domain RF filter based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). With the advent of high bandwidth, low V, electro-optical modulators, it has become feasible to modulate a very broad band RF signal (100 GHz) onto an optical carrier and distribute it by fiber with a respectable link gain.

MSTAR: an absolute metrology sensor with sub-micron accuracy for space-based applications

The MSTAR sensor (Modulation Sideband Technology for Absolute Ranging) is a new system for measuring absolute distance, capable of resolving the integer cycle ambiguity of standard interferometers, and making it possible to measure distance with subnanometer accuracy. The sensor uses a single laser in conjunction with fast phase modulators and low frequency detectors. We describe the design of the system - the principle of operation, the metrology source, beam-launching optics, and signal processing - and show results for target distances up to 1 meter. We then demonstrate how the system can be scaled to kilometer-scale distances and used for space-based applications.

A Novel Photonic Packet Switch with All-Optical Routing Control

A photonic packet switch having all-optical routing functionality is demonstrated. The device has the ability to self-route an incoming packet between two output ports depending on the presence or absence of a refer-ente wavelength in the packet. The underlying mechanism is the nearly-degenerate four-wave mixing (ND-FWM) interaction in a semiconductor gain medium. The implementation of the device in a broad-area trav-eling wave semiconductor optical amplifier shows a +8.2 dB switching efficiency and −28.8 dB crosstalk. The recognition bandwidth is as narrow as 0.03. A and the 3 dB switching bandwidth is 42 nm. We also obtain a high signal-to-noise ratio of 32.9 dB.