J. F. Weller

Injection locking of coupled‐stripe diode laser arrays

The control of the far‐field beam pattern and the spectrum of 10‐element laser diode array by injection locking to a single‐mode master laser are described. With less than 3 mW of injected power an array output of 105 mW at a single frequency with a 0.5° wide far‐field lobe is obtained. Similar results are observed when the entire array is illuminated by the master laser beam, or when only one of the stripes is illuminated. The narrow lobe contains 60–70% of the total power and is centered at an angle of about 4° relative to the normal of the array facet.

Second‐harmonic generation at 421 nm using injection‐locked GaAlAs laser array and KNbO3

Significant improvement in frequency doubling efficiency of a cw output of a GaAlAs laser diode is described. Up to 0.72 mW of 421 nm power was generated by illuminating a KNbO3 crystal with a 270 mW diffraction‐limited beam generated by an externally injection‐locked laser diode array, operating in a single‐mode and single‐far‐field lobe.

Injection locking and single‐mode fiber coupling of a 40‐element laser diode array

Near‐diffraction‐limited (0.13° wide) single‐lobe operation of a 40‐element AlGaAs array emitting 510 mW cw is obtained by external injection locking, with 11.0 mW of injected power incident on the array. The injected and the array output beams were tilted relative to the facet normal to allow for spatial separation of the two beams and efficient coupling into a single‐mode fiber; 150 mW was coupled into a 5‐μm core, polarization holding fiber.

Optical phase control of an optically injection-locked FET microwave oscillator

A simple technique is proposed and demonstrated for controlling the phase of an optically-injection-locked 7.2-GHz FET oscillator. The relative phase phi between the oscillator and the locking signal is adjusted by optically tuning the oscillator frequency. Locking characteristics described include locking bandwidth (2.6 MHz), phase tuning range (187 degrees ), phase modulation ( beta =0.69 at 500 kHz), and optical tuning (125 MHz). >

Picosecond optical mixing in fast photodetectors

We report a simple optical correlation technique which is capable of measuring the intrinsic response speeds of fast photosensitive electronic devices. The appeal of the method is that neither high‐speed electrical connections to a device nor cross‐correlation measurements between two devices are required. An example is given of measurements of the response speed of a GaAs Schottky barrier photodiode. Under appropriate illumination conditions the detector is found to be sufficiently fast to be capable of replacing optical second harmonic generation techniques for monitoring the quality of a beam of 1.5 ps pulses.

Optical Kerr effect in fiber gyroscopes: effects of nonmonochromatic sources

The effects of source bandwidth on the optical Kerr effect are calculated. We show that the nonreciprocal Kerr bias error in fiber gyroscopes may be substantially reduced by using broadband sources.

Spectral Characteristics of Semiconductor Lasers with Optical Feedback

Optical feedback-induced changes in the output spectra of several GaAlAs lasers operating at 0.83 µm are described. The feedback radiation obtained from a mirror 60 cm away from the laser is controlled in intensity and phase. Spectral line narrowing or broadening is observed in each laser depending on the feedback conditions. Minimum linewidths observed with feedback are less than 100 kHz. Improved wavelength stability is also obtained with optical feedback resulting in 15 dB less phase noise. Analytical model for the three-mirror cavity is developed to explain these observations.

Rapid continuous tuning of a single-polarization fiber ring laser

We have developed and studied what we believe is the first fiber laser operating in a single polarization at 1550 nm with PM fiber output and capable of wavelength tuning over a 20-nm bandwidth in less than 50 /spl mu/s. The fast wavelength tuning speed in a fiber laser is achieved by incorporating an acousto-optic tunable filter into the laser. The same filter is used in an optoelectronic feedback loop to suppress the relaxation oscillations induced by wavelength transitions.<<ETX>>

Single lobe operation of a 40‐element laser array in an external ring laser cavity

Single lobe operation of a 40‐element GaAlAs gain guided coupled stripe array emitting 500 mW cw is obtained in an external ring laser cavity. The cavity arrangement is equivalent to self‐injection locking of the array by its own output, which is first spatially filtered by a single mode fiber. Diffraction‐limited lobe width of 0.13° and single mode operation are demonstrated with a 90 mW single mode fiber output.

Injection-beam parameter optimization of an injection-locked diode-laser array

The dependence of the far-field distribution of an externally injection-locked array on the width and power of the injected beam was determined by numerical simulation. The fraction of total power contained in the diffraction-limited lobe portion of the far field was significantly larger for wide-beam injection (95%) than for single-point injection (70%). Qualitative agreement with experimental results using a 20-element array was observed.