Charles R. Lutz

Optoelectronic transmission and reception of ultrashort electrical pulses

We report on the recent advances in using integrated planar antenna technology to photoconductively generate and detect picosecond radiation. Detection of a single pulse of picosecond duration has been achieved using a coplanar antenna structure fabricated on a radiation‐damaged silicon‐on‐sapphire substrate.

Transient response of planar integrated optoelectronic antennas

Broadband tapered slot antennas monolithically integrated on ion damaged silicon‐on‐sapphire substrates are driven by picosecond photoconductivity to generate and detect millimeter waves. The time‐dependent electromagnetic impulse response of these transceivers is modeled by relating the antenna structure and the shape of the exciting pulse. The far‐field response is observed to consist of a traveling‐wave component and a standing‐wave component, which is also predicted by the model.

FAR-FIELD CHARACTERISTICS OF OPTICALLY PULSED MILLIMETER WAVE ANTENNAS

We describe a novel technique for measuring transient far‐field radiation patterns emitted from optically pulsed, broadband, integrated antennas using photoconductive sampling methods. These devices are capable of generating and radiating short electrical pulses which contain frequency components exceeding 80 GHz. The far‐field patterns in both the E and H planes are observed to consist of single, forward directed lobes which are shown to have a cosine‐squared dependence. In addition, there are no indications of any additional secondary sidelobes in either of the principal planes.

High power harmonically mode-locked cw-pumped Nd:YAG laser

A new cavity configured from commercially available parts including a harmonic mode locker has yielded stable 60-ps pulses and an average power of 14 W. Powers of up to 20 W are readily attained at the expense of pulse width. These are the largest peak powers yet reported for a single-lamp cw-pumped Nd:YAG laser.

Characterization Of High Speed Radiative Effects In Interconnects

The dominant factors which contribute to distortion of high speed electrical signals propagating along transmission line structures are discussed. Photoconductive sampling methods are used to characterize picosecond pulse propagation and dispersion properties of coplanar radiative electrical interconnects. In addition, we show that optoelectronic sampling techniques are an effective method for determining various characteristics of these antenna elements such as the far-field radiation patterns.

Optoelectronic Generation and Sensing of Millimeter Waves

Broadband tapered slot antennas, monolithically integrated with picosecond optoelectronic switches, are used to generate, control and sense millimeter wave radiation. These devices can be easily integrated with millimeter wave circuit components due to their planar geometry. This method of transmitting information eliminates many of the limitations inherent with transmission line structures and demonstrates the potential for controlling extremely wideband electrical signals.

Picosecond Optoelectronic Transceivers

Picosecond photoconductivity is used to generate and sense transient millimeter wave radiation from monolithic broadband tapered slotline antennas integrated on ion-damaged silicon on sapphire substrates. The far field is observed to consist of a traveling wave component and a standing wave component. The time-dependent electromagnetic impulse response of these optoelectronic transceivers is also modeled.