Bogdan Szafraniec

Coherent optical spectrum analyzer

In this letter, we demonstrate coherent optical spectrum analysis with /spl sim/70-dB dynamic range based on a swept-tuned optical local oscillator and a coherent receiver operating in the 1.5-/spl mu/m wavelength hand. Measurement principles are presented along with high-resolution measurements of distributed feedback laser spectra.

Theory of polarization evolution in interferometric fiber-optic depolarized gyros

Single-mode (SM) fiber which is used in the sensing coil of depolarized interferometric fiber-optic gyroscopes (IFOGs) does not maintain the polarization state of light. As a consequence, the state of polarization evolves freely over the length of the sensing coil and over environment. The polarization evolution is induced by birefringence within the SM coil. Variations of this birefringence may lead to nonreciprocal errors whose treatment is presented in this paper together with signal fading and the mean wavelength stability. Thus, this treatment provides a relatively comprehensive analysis of polarization evolution in depolarized gyroscopes. The analysis leads to the conclusion that the depolarized gyro architecture with two depolarizers on the opposite sides of the gyro loop must be used to obtain low-drift behaviour.

Fiber optic gyros for space, marine, and aviation applications

Fiber-optic gyroscopes (FOGs) are under development at Honeywell as the primary next generation inertial sensor. The open-loop FOG technology has been successfully transitioned to production for attitude heading reference systems and the results of this effort are reported. New developments in closed-loop FOG technology aimed at high performance space applications and at navigation grade aviation applications, are underway. In the former case, results on a high precision FOG are reported. In the latter case, special emphasis is placed on improvements of depolarized FOG technology, which promises to produce a low cost navigation grade sensor.

Polarization modulation errors in all-fiber depolarized gyroscopes

Polarization modulation errors in all-fiber depolarized gyros having imperfect depolarization are examined. As in the case of PM fiber gyros, birefringence modulation is shown to give rise to quadrature errors. In addition, we demonstrate the existence of a small time lag between the modulation of the two linear polarization states of a fiber-wound PZT modulator by correlating this effect with an associated signal channel error. Proper frequency operation and/or good depolarization of the light act to reduce both types of errors. >

PARTIALLY POLARIZED FIBER-OPTIC GYRO

We present a new design for an all-fiber-optic gyroscope that makes use of a single-mode coil containing a Lyot depolarizer along with a partial depolarizer placed between the polarizer and the loop coupler. This design provides an optimal trade-off between the suppression of polarization errors and the reduction of drift errors arising from external magnetic f ields and changes in temperature.

Performance improvements in depolarized fiber gyros

We describe amplitude-type polarization errors in depolarized fiber gyros and show a management scheme for their suppression. Prototypes operating both at 0.8 micrometers and 1.3 micrometers wavelengths exhibiting navigation grade drift and noise performance have been realized.

Fiber-optic gyro development for a broad range of applications

Progress in fiber-optic gyroscope development at Honeywell is reported here. The results illustrate the versatility of the technology, showing its potential to meet both the low-cost, small-sized needs of tactical guidance, as well as the very high perfomance needs of inertial navigation and precision applications. In the case of inertial navigation, data is presented that illustrates the possibility of employing a low-cost depolarized design for this use.

Progress in low cost interferometric fiber optic gyros

Low cost interferometric fiber optic gyros (both polarization maintaining and depolarized types) having bias drift less than one degree/hr over wide temperature ranges are reported. The depolarized fiber gyros exhibit significantly lower sensitivity to temperature transients than the polarization maintaining fiber gyros.

Depolarized interferometric fiber-optic gyro with improved polarization error suppression

We describe sources of polarization errors in depolarized IFOGs and methods for enhancing their suppression. A test-gyro circuit and associated experimental results showing 0.1 degree/hour (one-sigma) open-loop bias stability over a thermally dynamic environment are presented.

Fully integrated microwave frequency synthesizer on heterogeneous silicon-III/V

We demonstrate a photonic microwave generator on the heterogeneous silicon-InP platform. Waveguide photodiodes with a 3 dB bandwidth of 65 GHz and 0.4 A/W responsivity are integrated with lasers that tune over 42 nm with less than 150 kHz linewidth. Microwave signal generation from 1 to 112 GHz is achieved.