Showing papers on "Injection locking published in 1983"

Microwave signal generation with injection-locked laser diodes

Abstract: Heterodyne detection of the light from two slave lasers injection locked to FM sidebands of a modulated master laser is used to generate a narrowband microwave signal at 10.5 GHz.

Optical Control of GaAs MESFET's

Abstract: Theoretical and experimental work for the performance of GaAs MESFET's under illumination from light of photon energy greater than the bandgap of the semiconductor is described. A simple model to estimate the effects of light on the dc and RF properties of MESFET'S is presented. Photoconductive and photovoltaic effects in the active channel and substrate are considered to predict the change in the dc equivalent circuit parameters of the FET, and from these the new Y- and S-parameters under illumination are calculated. Comparisons with the measured S-parameter's without and under illumination show very close agreement. Optical techniques can he used to control the gain of an FET amplifier and the frequency of an FET oscillator. Experimental results are presented showing that the gain of amplifiers can be varied up to around 20 dB and that the frequency of oscillators can be varied (tuning) around 10 percent when the optical absorbed power in the active region of the FET is varied by a few microwatts. When the laser beam is amplitude-modulated to a frequency close to the free-running FET oscillation frequency, optical injection locking can occur. An analytical expression to estimate the locking range is presented. This shows a fair agreement with the experiments. Some suggestions to improve the optical locking range are presented.

Injection-locking unstable resonator excimer lasers

Abstract: We review the basic criteria for effective and efficient injection locking of high-power excimer lasers, and enumerate the various parameters of practical concern for experimental implementation. Various injection schemes are compared and the fundamental limitations of the process are covered. Corroborative experimental results are also reviewed, and applications made possible by injection locking are discussed.

Frequency multiplex system using injection locking of multiple laser diodes

Abstract: An optical frequency division multiplex system including a transmitter, a receiver, and a transmission path connecting the transmitter to the receiver. In the transmitter a master laser is operated to produce a central peak at an optical frequency f o with side peaks separated by an amount Δf running to both sides of the central peak. The master laser output goes through an optical isolator to an optical coupler where it is split up into N+1 beams. Each optical output from the coupler is then positioned to be coupled into N slave lasers. Each slave laser is tuned to approximately coincide with one of the side peaks thus producing a single output frequency of (f o ±nΔf) from each slave laser diode. Electrical modulating signals for each of N information channels are applied separately to modulate the phase of each of the slave laser outputs. The outputs of the slave lasers are then recombined in a N×1 optical coupler, the output of which is transmitted over a single-mode fiber linking the transmitter to the receiver. One of the outputs of the 1×(N+1) coupler is transmitted to the receiver over a second single-mode fiber. At the receiver, the master laser carrier is split into N spatial components by a 1×N coupler. These are then filtered and amplified by a second group of N slave lasers. The output from this second unmodulated group of slave lasers is combined with the combined outputs from the modulated slave lasers in an array of 2×1 optical couplers. Finally, the light signals emerging from the couplers are converted to electrical signals for the N information channels by an array of photodetectors.

Microwave oscillator injection locked at its fundamental frequency for producing a harmonic frequency output

Abstract: A microwave oscillator suitable for millimeter wavelengths comprises a Gunn diode (3) coupled to a waveguide (1) by a resonant-cap structure (5,6). The diode (3) generates microwave energy both at a fundamental frequency f o which is below the cut-off frequency of the waveguide (1) and at a second harmonic frequency 2f o above cut-off. To control the generation of microwave energy at 2f o , energy at f o is coupled into the waveguide (1) from an adjacent further waveguide (9) above its cut-off, by means of an electric probe (8) extending close to the cap (5). The probe (8) may couple in a locking signal at or close to the free-running value of f o from another oscillator having better noise performance and electronic tuning, thereby locking 2f o to twice the frequency of the locking signal, or alternatively may couple to a varactor-tuned cavity resonant at f o .

Optical injection locking of X-band FET oscillator using coherent mixing of GaAlAs lasers

Abstract: A 9.6 GHz GaAs FET oscillator was optically injection locked at the fundamental frequency. The locking bandwidth was 1.6 MHz. The optical injecting signal was generated using coherent mixing of two semiconductor lasers injection locked by different FM sidebands of another laser.

Optical injection locking of solid-state oscillators by frequency-multiplexed injection-locked, laser diodes

Abstract: The optical injection-locking of an FET oscillator is accomplished by injecting the beat signal between two coherently mixed slave lasers, which are locked to different harmonics of a modulated master laser, into the FET oscillator to be locked. 120 GHz injection-locking beat signals are possible using this technique.

Single-mode operation of Doppler-broadened lasers by injection locking.

Abstract: A multimode He–Ne laser can be forced to oscillate in a single mode by injecting a narrow-band signal into the resonator. We show experimentally that the minimum injected intensity required for single-mode operation occurs at an injection frequency detuned from line center. This is in agreement with the results from a semiclassical theory of an inhomogeneously broadened injection-locked laser.

Mode selection and frequency tuning by injection in pulsed TEA-CO 2 lasers

Abstract: An analytical model is presented which describes certain characteristics of the injection locking of a pulsed TEA-CO 2 laser by means of tunable CW laser radiation. The requirements for SLM generation as the injection frequency is tuned away from line center are discussed. Results indicate the practical importance of the locking time, a parameter which depends on both the injected power and the detuning from the molecular line center frequency.

Polarization coupling effects in transversely excited atmospheric CO2 lasers: Application to single axial mode operation

Abstract: We report the observation of anomalous polarization coupling effects occurring in injection‐locked transversely excited atmospheric (TEA) CO2 lasers, deduced from studies of the injection detuning parameter under varying conditions of polarization and injection power. For the special case of injection with orthogonally polarized radiation we have determined the existence of an optimum operation point, exhibiting minimum sensitivity of single mode operation to the detuning parameter. Off‐resonance injection locking of untuned TEA cavities is also discussed.

Direct Measurement of the Nonlinear M. I. C. Oscillator Characteristics Using Injection Locking Polar Diagram.

Abstract: Direct measurement of principal characteristics of a negative resistance nonlinear M. I. C. Oscillater using a network analyser is presented. Theoretical considerations and experimental results are shown for the injection locking polar diagram obtained by placing the oscillator directly at the unknown port without the use of a circulator.

Hold-In Characteristics of an Extended Range Gunn Oscillator System

Abstract: This paper describes a new Gunn oscillator system having an additional arrangement for controlling the instantaneous frequency of the oscillator through an automatic frequency control circuit. By utilizing this new technique, based upon the principle of self tracking, the locking bandwidth of an injection-locked Gunn oscillator can be increased to a huge extent without affecting its stability. Experimental observations are found to be in good agreement with the conclusions of the analytical approach.

Stable single axial mode Q switched laser oscillator with injection locking

Abstract: A stable high gain laser includes a Q switched multiple axial mode high gain oscillator, an oscillator for generating a stable optical wave at a first frequency, the first frequency being within the band of the multiple modes of operation, and a coupler for injecting the stable optical wave into the high gain oscillator whereby the axial mode nearest to the frequency of the injected wave selects a single axial mode and through gain saturation suppresses other modes of the high gain oscillator.

Experimental 1.5 μm coherent optical fibre transmission systems

Abstract: The authors consider the design requirements for 1.52 μm coherent optical fibre transmission systems. Some of the essential requirements are: narrow linewidth sources, polarisation stable transmission media, low insertion loss optical mixers and frequency tracking or phase locked local oscillators. Having been successful in reducing the linewidth of semiconductor lasers to less than 30 kHz, by using injection locking techniques, and in fabricating optical mixers with insertion losses of the order of dB, they have been able to experiment with coherent optical fibre transmission systems to assess their practicability. In this paper it will be shown that coherent systems can be operated over long lengths of conventional low loss monomode fibre without any polarisation penalty and give far better performance than direct detection systems.

Dual Gunn diode self-oscillating mixer

Abstract: A dual Gunn self-oscillating mixer is shown which can mix signals in the range substantially without introducing any noise and with high input signal power handling capacity and with higher output mixed signal power than conventional, owing to boosted power from more than one microwave cavity. The device is comprised of two cavities and connected by a 180° phase shift coax line for injection locking, or a cavity wall hole in yet another embodiment. The device handles larger power levels without burning out as compared to conventional type mixer devices such as Schottky barrier diodes having nearly 30 times the burnout susceptibility.

Optical Injection Locking of Baritt Oscillators

Abstract: Optical injection locking of BARITT oscillators is investigated. Preliminary experimental results are presented for the first time. A sirmple first-order locking theory gives reasonable agreement with measurements.

Generation of single-longitudinal-mode gigabit-rate optical pulses from semiconductor lasers through harmonic-frequency sinusoidal modulation

Abstract: Generation of optical pulses at gigabit rates from semiconductor lasers by means of harmonic-frequency sinusoidal injection current modulation has been demonstrated for the first time. It was confirmed that these optical pulses consisted of one longitudinal oscillating mode because of the presence of a ‘self-optical injection-locking effect’.

Injection Locking of a Nitrogen Laser Pumped Dye Laser

Abstract: Injection locking of a N2-laser pumped dye laser is investigated. The locking efficiency is measured as a function of injecting beam intensity, injecting beam wavelength, and delay time between an injecting laser pulse from a master oscillator and a pumping N2-laser pulse at a forced oscillator. The dye laser output of 1.2 kW with linewidth of 0.2 nm is obtained at locking efficiency ρ=0.8 when the injecting intensity is about 10 kW/cm2.

Injection locking of wide-aperture TEA CO2 lasers.

Abstract: The performance and operation of a TEA CO/sub 2/ laser is described and the single longitudinal mode (SLM) TEM/sub 00/ pulses are analyzed. The wide-aperture SLM output was reproducible 98% of the time. (AIP)

Three diode balanced mixer

Abstract: A triple Gunn diode self-oscillating mixer system is shown which can mix nals in the VHF range substantially without introducing any noise and with high input signal power handling capacity and with higher output mixed signal power than conventional, owing to boosted power from more than one microwave cavity. The device is comprised of three self-oscillating Gunn diode cavities connected by 180° phase shift coax lines for injection locking. The device handles larger power levels without burnout as compared to conventional mixer devices such as Schottky barrier diodes having nearly 30 times less burnout capacity.

Z-Transform Analysis of a SAW Delay Line Oscillator

Abstract: On montre que la transformation Z et l'analyse du spectre de puissance peuvent facilement etre appliquees a l'oscillateur a ligne a retard a onde acoustique de surface. On etablit les relations de densite spectrale du bruit de phase pour un oscillateur libre. L'analyse est etendue pour inclure un oscillateur verrouille par injection, pour lequel on etablit les relations d'Adler du blocage par injection

Noise Due to Pulse-to-Pulse Incoherence in Injection-Locked Pulsed Microwave Oscillators

Abstract: It is demonstrated that partial pulse-to-pulse coherence in a pulsed oscillator system gives rise to no excess noise, which may be significantly reduced by injection Iocking.

Free Harmonic Oscillator

Abstract: In this chapter the aim is to describe the oscillatory behaviour of a simple system when vibrating freely, that is, without any external influences after the initial start-up.

Synchronization Effects in a Submillimeter Josephson Self-Oscillator

Abstract: We present an experimental and theoretical study of injection locking in an oscillator in the presence of noise. The experiment is performed with a Josephson point-contact self-oscillator heterodyne receiver irradiated by a very weak = 1-THz signal. A general calculation of the oscillator response at low injection level is made based on the theoretical treatment of Stratonovitch. We show that the Josephson oscillator described by the RSJ model obeys the general locking equation in the presence of noise. We assume a simple evolution law of the oscillator spectrum as a fnnction of detuning and calculate its response. The experimental results are compared with computer calculations and the implications are discussed.

Four-phase characteristics of a multimode oscillator with second and third harmonic oscillations

Abstract: This paper describes the multimode synchronisation of an oscillator having three resonators of fundamental, second and third harmonic frequencies with an external signal injected. Assuming that the current/voltage relationship of the nonlinear conductance is given by a third-order polynomial, the simplified equations for the amplitude and phase of oscillation are derived by using the method of equivalent linearisation. It is found that four output phases exist which are separated by /2 from one another at the fundamental frequency when an external signal is applied at frequency close to the second harmonic of the oscillator.

Further studies on injection synchronized oscillator

Abstract: Injection-locking properties of a practical oscillator have been re-examined with particular emphasis on the flow of current into the input port of the active device. This approach has made it possible to understand various types of asymmetric locking characteristics observed in practice. Detailed theoretical analyses have been carried out to take care of the effect of second- and third-harmonic distortion components through the active device. Also presented are experimental results in support of the theoretical conclusion.

Damped Free Harmonic Oscillator

Abstract: The aim in this chapter is to describe the free oscillatory behaviour of a simple vibratory system in which some energy loss mechanism is present.