M. J. Marrone

Optimization and stabilization of visibility in interferometric fiber-optic sensors using input-polarization control

The effects of input polarization on the output fringe visibility of two-beam interferometric fiber-optic sensors are investigated, and an analysis which predicts the existence of input states of polarization of eigenmodes of the interferometer for which optimum output visibility is obtained is presented. Experimental results obtained using both a bulk-optic and a fiber Mach-Zehnder interferometer are reported that verify this analysis. Active feedback stabilization of the output fringe visibility of an interferometric sensor using automatic input-polarization control is demonstrated. >

Analysis of input-polarization-induced phase noise in interferometric fiber-optic sensors and its reduction using polarization scrambling

The dependence of the phase shift of an interferometric fiber sensor on the input state of polarization is analyzed, and it is shown that fluctuations in the input polarization to a fiber interferometer can lead to the generation of excess phase noise. The relationship between this effect and the variation in visibility with input polarization is described and theoretically confirmed. The use of depolarized source light to eliminate input-polarization-induced excess phase noise is theoretically and experimentally demonstrated. >

Observation of input-polarization-induced phase noise in interferometric fiber-optic sensors.

It is shown that polarization fluctuations in the input fiber to an interferometric sensor can result in the generation of excess phase noise in the output. Experimental observations of this phenomenon are compared with theoretical models, and the impact of this noise source in interferometric sensors is briefly discussed.

Temperature dependence of stress birefringence in an elliptically clad fiber

The stress birefringence in a fiber with a three-component silica-glass elliptical cladding is found to be a strongly nonlinear function of temperature. The observed birefringence is a factor of 1.6 greater than that predicted from linear approximations of this dependence and estimates of the fiber materials properties. The fibers birefrin-gence can be predicted from a linear extrapolation of the low-temperature data.

Continuous-wave laser action of (F 2 + )A centers in sodium-doped KCl crystals

Broadly tunable laser action is reported for the (F2+)A center in sodium-doped, additively colored KCl. The laser is continuously tunable from about 1.62 to 1.91 μm, has a continuous-wave threshold of under 10-mW absorbed power, and can be stored for at least limited periods at room temperature without losing its lasing capability.

Radiation‐induced luminescence in silica core optical fibers

The spectrum of the luminescence in silica core optical fibers under x‐ray excitation has been observed to consist of two distinct emission bands at 450 and 650 nm. The contrasting dose‐dependent behaviors of the two bands show that they are associated with different luminescent centers in the glass matrix. The application of the radiation‐induced luminescence in fibers for radiation detection and real‐time dosimetry is outlined.

Dichroic absorption of m centers as a basis for optical information storage.

The rotational properties of M centers in alkali halides are investigated as a possible basis for storing information. Measurements using a NaF matrix indicate that high storage density, high writing efficiency, thermal stability, and nondestructive readout are attainable in a practical situation at room temperature or lower. However, temperatures below 300 K are necessary for fatigue-free operation in the present material.

Internal rotation of the birefringence axes in polarization-holding fibers

An internal rotation of the birefringence axes has been measured in a variety of polarization-holding fibers. The rotation of the axes causes coupling of the major-field components of the fundamental modes, which limits the polarization-extinction ratio in short lengths of birefringent fibers to -45 dB in some cases. A practical consequence of the rotation of the axes is a reduction of the polarization-holding ability of devices such as fiber couplers that are made with these fibers.

Fiber Bragg grating high-magnetic-field probe

We describe a novel fiber probe for monitoring a.c. high magnetic fields which is based on detecting the shift in the Bragg condition of a fiber Bragg grating due to magnetically induced circular birefringence. The technique should be usable over a wide range for fields above 1 Gauss.

Repetitively pulsed mode-locked Nd:phosphate glass laser oscillator-amplifier system

Performance of a repetitively pulsed mode-locked Nd:glass laser system employing athermal phosphate glass in the oscillator and amplifier stages is described. Improved passive mode-locking characteristics of the oscillator are achieved through use of a l00-microm thick intracavity etalon, enabling reliable generation of transform-limited pulses typically of 5-psec duration. The system produces 1054-nm pulses of high beam quality and ~25-mJ energy at a pulse repetition rate of ~0.2 Hz. Subsequent frequency-doubling steps give conversion efficiencies of ~50% and 25%, respectively.