Showing papers on "Injection locking published in 1988"

Locking bandwidth and relaxation oscillations of an injection-locked semiconductor laser

Abstract: Theoretical and experimental results from an injection-locked semiconductor laser are reported. The measure deposition and size of the locking bandwidth compare favorably to those calculated using the authors' model of the injected laser. The effect of synchronization on the intensity level is pointed out. The usefulness of the technique in terms of modulation is estimated based on the behaviour, amplitude, and frequency of the relaxation oscillations which are the main limiting factor. >

Improved mode locking of an F-center laser with a nonlinear nonsoliton external cavity.

Abstract: We demonstrate that solitons are not essential for the operation of the soliton laser. The external cavity employed contains an optical fiber with negative group-delay dispersion and therefore does not support bright solitons. Thus the improved mode locking cannot be attributed to the injection of an N = 2 soliton.

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

Abstract: 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.

All-optical timing extraction using a 1.5μm self pulsating multielectrode DFB LD

Abstract: All-optical timing extraction from an intensity modulated 196 Mbit/s return to zero optical data stream by the injection locking technique, using a 1.5μm self-pulsating multielectrode DFB LD is demonstrated. A frequency lock-in range, which depends upon both the injection signal level and the length of space continuation is investigated.

Efficient narrow‐band direct modulation of semiconductor injection lasers at millimeter wave frequencies of 100 GHz and beyond

Abstract: It has been demonstrated both theoretically and experimentally that it is possible to mode lock semiconductor lasers at millimeter wave frequencies approaching and beyond 100 GHz. The mode‐locked output usually takes the form of sinusoidal modulation, and can be regarded for practical purposes as a highly efficient means of directly modulating an optical carrier in a narrow band at millimeter wave frequencies. In active mode locking, the external signal efficiently creates the optical modulation, while in passive mode locking a small external signal imposes its information on the optical carrier by injection locking the passive mode‐locked output. Experimentally, we have demonstrated passive mode locking at 70 GHz using a tandem contact GaAs laser.

Amplitude-modulation sideband injection locking characteristics of semiconductor lasers and their application

Abstract: Amplitude-modulation (AM) sideband injection-locking characteristics of 1.3- mu m distributed-feedback lasers are studied experimentally. When the master laser light, which is amplitude-modulated, is injected into slave lasers, the slave lasers can be phase-locked to each sideband of the master laser. This means that the frequency separation between slave lasers can be controlled by the modulation frequency of the master laser. By controlling the injection power, it is possible to achieve a very stable AM sideband injection-locked state of slave lasers. Results on phase-noise and phase-modulation measurements, the frequency stabilization between two channels, and the injection locking to a short pulse are presented. On the basis of the experimental results, an example for designing the multifrequency laser transmitter by means of the AM sideband injection-locking and the mode-locking techniques is described. >

Frequency measurement of a CH/sub 4/ hyperfine line at 88 THz/'optical clock'

Abstract: A frequency-measurement chain was used to measure the frequency of a hyperfine line of the nu /sub 3/P(7) CH/sub 4/ multiplet, which was resolved by a linear optical Ramsey resonance technique. A frequency of 88, 376, 181, 599.7+or-1 kHz is found. The Ramsey experiment was used as a clock; to approximately 100 s the stability of this optical clock is equal to a high-performance commercial Cs clock. It is concluded that the frequency division necessary for optical transitions to be used as a clock does not necessarily introduce the noise and errors which would a priori rule out optical transitions as candidates for good clocks. >

Picosecond Nd:YAG regenerative amplifier with acoustooptic injection and electrooptic VFET pulse switchout

Abstract: A system is described for amplification of low-power 80-ps pulses from a CW mode-locked YAG laser to greater than 10-MW peak power at kilohertz repetition rates. It is shown how to optimize the resonator for high-power operation and avoidance of optical damage. A novel method of injection locking which uses an acoustooptic modulator is presented. Reliable pulse switching and cavity dumping are accomplished with a high-voltage driver using VFETs. >

Mode stability of radiation-coupled interinjection-locked oscillators for integrated phased arrays

Abstract: An analysis is presented of a two-element, 10-GHz array consisting of two oscillators coupled solely by means of the free-space interaction between their respective antenna elements. The oscillators are modeled as energy-storing L-C tank circuits in parallel with voltage-dependent negative conductances. A simplified far-field slot antenna model is used to derive the mutual admittance of the two antennas. Even-odd mode analysis yields the normal modes of the system, and a theorem from averaged potential theory is used to determine which mode is stable. Two microstrip Gunn diode oscillators were built to verify the essential features of the model. Oscillator frequencies, relative phases, and radiation patterns were measured as functions of the interantenna distance, and the periodic alternation of modes with distance predicted by theory was confirmed quite well. >

Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements

Abstract: Theoretical and experimental frequency narrowing studies of a Ti-sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported. >

Spatial power combining using active microstrip patch antennas

Abstract: Active antenna elements have been fabricated using Gunn diodes and microstrip patch antennas. The power outputs from two of these elements have been successfully combined in space. Frequency coherency was achieved by injection locking using either the spatial locking technique or the mutual coupling locking technique.

A self-injection locked, Q-switched, line-narrowed Ti:Al/sub 2/O/sub 3/ laser

Abstract: Line-narrowing, Q-switched, and self-injection locking are studied independently and as a system. Line narrowing is shown both theoretically and experimentally to depend on the inverse square root of the pulse evolution time interval. Q switching of the Ti:Al/sub 2/O/sub 3/ laser is demonstrated and the laser output energy as a function of the Q-switch delay is investigated. Self-injection is demonstrated and the operation of the laser is explored as a function of loss and the Q-switch delay. Self-injection locking is demonstrated and the performance as a function of the Q-switch delay is determined. >

Coherent summation of injection-locked, diode-pumped Nd:YAG ring lasers

Abstract: A binary grating has been used to achieve coherent summation of diode-laser-pumped Nd:YAG ring lasers operating at 1.06 μm. Mutual coherence of two such devices was achieved by optical injection locking. This is believed to be the first demonstration of cw injection locking of solid-state lasers other than semiconductor diode lasers. By combining two beams, an efficiency of 75% (92% of the theoretical limit) has been demonstrated in a configuration that could be used to combine a large number of individual lasers.

High-power, mode-locked Nd:fibre laser pumped by an injection-locked diode array

Abstract: A neodymium-doped fibre laser has been actively mode-locked to produce pulses shorter than 120 ps using an intracavity acousto-optic loss modulator. The laser operated at 1.088 mu m at an average power of 5 mW when pumped by an injection-locked diode array, which coupled approximately 40 mW of 0.82 mu m into the fibre. A peak pulse power of 1 kW was obtained in Q-switched operation.

Simulation of optically injection-locked microwave oscillators using a novel SPICE model

Abstract: Optical injection-locking of GaAs field-effect transistor microwave oscillators has been examined experimentally as well as by using two different optical interaction models. An additional simulation program with IC emphasis (SPICE) circuit for observing small locking ranges is also described. This first-order interaction model which utilizes a standard version of SPICE produces predictions of injection-locking range in excellent agreement with measured results. These tools allow the oscillator designer to optimize the injection-locking performance by analyzing various circuit topologies and DC bias levels. >

Injection locking of high-power pulsed lasers. I. Monochromatic injection

Abstract: The theory of injection locking is based on the realistic situation where the injected intensity is much larger than the spontaneous noise intensity and smaller than the saturation intensity. Wideband homogeneously broadened lasers with injection are analyzed in the small-signal regime, including diffraction effects. The relevant equation for the injection-driven field is an iterative equation solved in the time domain. Multimode behaviors can be predicted. Injection locking is the result of a competition between the injection- and noise-driven fields. The laser behaviour is fully characterized by locking curves in the 2-D space of the injection parameters and by locked mode distributions. >

Single-state high-beam-quality XeCl laser with a phase-conjugate Brillouin mirror

Abstract: A single-stage high-beam-quality XeCl laser, consisting of an oscillator and a double-pass amplifier with a phase-conjugate Brillouin mirror with no optical coupling between the oscillator and the amplifier, is discussed. Maximum output energy of 20 mJ with a pulse duration of 13 ns full width at half maximum has been obtained with a 0.0015-AA (469-MHz) linewidth, 1.2*diffraction-limited beam divergence from a circular 8-mm diameter beam. >

Direct optical injection locking circuitry utilizing optical oscillator tuning

Abstract: An optical injection locking oscillator is comtemplated having a tuning device. The tuning device generates a DC voltage proportional to the resonant frequency of a modulated light used to injection lock the free running oscillator. The DC voltage is applied to a varactor capacitor within the oscillator to bring the frequency of oscillation within a close proximity to the modulating frequency of the light. This facilitates injection locking, whereas frequencies of oscillation outside a certain locking range will not facilitate injection locking. The modulated light then locks the oscillator into a desired resonant frequency. A second embodiment contemplates using a YIG oscillator regulated by a DC current generated within the tuning device.

Symmetric waveguide junction combiner

Abstract: A microwave power combiner having a spherical region from which six rectangular waveguides extend oppositely along mutually orthogonal diameters. The long dimension of each waveguide cross section extends along a diagonal of a cube circumscribing the region and extends orthognally to this long dimension of the opposite waveguide. One waveguide is an input for an injection locking signal, and four waveguides are inputs for power to be combined in the region from oscillators controlled by the signal. No circulator is required, and the combined power may be output through the remaining waveguide or through the injection locking input waveguide. A number of the combiners may be connected with the output of one combiner serving as an injection locking input or as one power input to another of the combiners.

Direct timing extraction in a modified-Manchester coded picosecond optical pulse fibre optic transmission system

Abstract: Direct timing extraction in a modified-Manchester-coded fibre optic transmission system is demonstrated. The presence of the clock signal in the received data is used to injection lock an electronic oscillator thus generating a large timing signal. The technique is also suitable for optical injection locking for timing extraction.

Coupled cw dye lasers using intracavity four-wave mixing.

Abstract: An experimental investigation of laser-oscillator frequency locking by a four-wave interaction was conducted. An experiment was performed that successfully demonstrated the locking of two cw dye lasers using this concept with Na vapor serving as the nonlinear (coupling) medium.

Optical Control Of Microwave Devices: A Review

Abstract: This paper reviews the basic optical techniques for controlling microwave signals. First, the theory of how an optical signal can affect the microwave signal will be covered, followed by a review of applications in the various areas to illustrate what has been accomplished in the use of optical techniques to control microwave signals. Optical techniques for processing microwave signals can be broken into three major categories related to how the light affects the microwave signal. First is the photogeneration of charge carriers, in which the light generates holes and electrons. This effect has been used to produce phase shifting, on/off switching, modulation, injection locking, and also direct conversion of DC to microwaves. The second way that light can affect the microwave signal is in a photodlode, by generating a photocurrent to be used for on/off switching, microwave pulse generation, injection locking, or for modulating an output beam for the transmission of a microwave signal. The third technique involves interference effects, or heterodyning, used to generate CW microwave signals. An additional topic covered is the monolithic integration of optical and microwave devices to produce opto- microwave integrated circuits. Finally, some systems applications and requirements for these devices are discussed.

Standard frequency clock generator

Abstract: PURPOSE: To always generate a clock signal of high precision by switching one of a highly stable oscillator like a cesium oscillator and quartz oscillators subordinate to this oscillator to another at the time of the occurrence of trouble in the output of one of these oscillators. CONSTITUTION: Changeover switches 14 and 15 are inserted between two quartz oscillators 12 and 13 as subordinate oscillators and synthesizers 16 and 17 to always monitor relations between outputs of a cesium oscillator 11 and quartz oscillators 12 and 13. When trouble occurs in quartz oscillators 12 and 13, signals of these oscillators are switched to the signal of the cesium oscillator 11 and this signal is supplied to synthesizers 16 and 17. Thus, the clock signal high in precision is always generated. COPYRIGHT: (C)1990,JPO&Japio

Injection locking experiment at the UCSB FEL

Abstract: The free electron laser at the University of California at Santa Barbara (UCSB FEL) is driven by an electrostatic accelerator with an electron beam recovery system. Because of the pulse to pulse terminal voltage fluctuations and the stochastic nature of the laser startup process the lasing frequency varies randomly by about 0.1%. To eliminate this effect, an experiment is carried out where power from an external coherent source is injected into the laser cavity and is expected to lock the laser to a fixed frequency. Several sources such as continuous and pulsed molecular far-infrared (FIR) lasers as well as backward-wave oscillators are considered on the basis of power, bandwidth and tunability. In all cases the power/bandwidth is many times higher than the FEL spontaneous emission. Preliminary results, using a pulsed FIR laser driven by a TEA CO 2 laser show an early startup of the FEL pulse increase in magnitude and achievement of saturation dictated by the characteristic spectral sweep of the UCSB FEL gain curve.

Generation of self-sustained optical pulses from transients in external cavity semiconductor lasers

Abstract: A novel technique to achieve self-sustained picosecond optical pulse-train generation at Gbit/s rates is presented. The technique relies on the nature of external cavity laser-switching transients and injection-locking. Preliminary experimental results confirm the practicality of the proposed technique.

Dissipative dynamics of a harmonic oscillator with environmentally caused frequency modulation

Abstract: The primary objective of the present work is an exact theoretical analysis of a vibrational dephasing process. The author has investigated a microscopic counterpart of the well known stochastic model of random harmonic oscillator frequency modulation. The author has found an exact expression for the oscillator coordinate relaxation. Several principal features of the solution appear to be quite different from the results based on the random frequency modulation model. (i) The envelope function of the oscillator coordinate time dependence is a function of temperature and it reveals definite types of coherent beats. (ii) The 'frequency' of the coordinate oscillations is time dependent and exhibits definite shift relative to the bare oscillator frequency when time goes from zero to infinity. (iii) Both the envelope function and the 'frequency' of the coordinate oscillations depend on the initial oscillator energy. This demonstrates the interaction-introduced non-linearity of the resulting dynamics.

High-Power 80-Ns Transform-Limited Nd:YAG Laser

Abstract: David G. ScerbakElectro -Optics TechnologyFremont, CA 94538ABSTRACTThe construction and operation of a long pulse, single -mode Nd:YAG laser isdescribed. The laser is configured around an injection- seeded, unstable oscillator /singleamplifier and produces 80 ns pulses at 10 Hz with pulse energies of over 300 mJ. Whenfrequency doubled, the infrared is converted to a 56 ns pulse at 532 nm with a Fourier -limited linewidth of 8 MHz. This approach brings the Nd:YAG source to within the bandwidthdomain normally dominated by visible CW lasers, but at a considerably higher power, thusproviding an attractive alternative for applications in high resolution spectroscopy andnon -linear studies.1. INTRODUCTIONThe importance of narrowband laser light to high resolution spectroscopic studies iswell recognized. While pulsed sources have found some application, the use of linewidth-narrowed and stabilized CW ion and dye lasers has long been the convention in fulfillingexperimental requirements for narrow bandwidths of better than 10 MHz. Unfortunately, CWlasers rarely provide line- narrowed powers greater than several watts without extraordinaryattention to stabilization and cooling requirements. For kilowatt or greater powers, pulsedsources appear far more practical and efficient, but only if the coherence properties of CWlasers can be emulated. With the recent development of laser- diode -pumped, single -modeNd:YAG lasers1,2,3 and the demonstrations of injection locking`,' Fourier- limited operationof high -power Nd:YAG lasers is now easily performed and commercially available. Though mostattention has been directed toward highest power pulse durations of around 10 ns, to producelinewidths of less than 10 MHz, pulses of greater than 44 ns must be generated.The production of long single mode pulses in Nd:YAG may be approached in severalways. Certainly the most versatile source would result from chain amplifying an acousto- orelectro- optically shaped single mode CW laser emission. In order to compete with the powerlevels of other available continuous lasers, however, this method can become quite costlyand complex, though multipass slab amplifier geometries promise to make this a moreattractive technique.6 Long pulses may also be generated in stable or unstable Q- switchedNd:YAG oscillator configurations. Lengthening the pulse build -up time or forcing thestimulated photons within the cavity to circulate longer before saturating the rod gainresults in a longer ejected pulse. Furthermore, injection locking these longer pulses to asingle mode master frequency yields narrowband light robust enough for immediate poweramplification.We have constructed a stable source of high power, Fourier transform -limited, 80 nswide laser pulses using an injection -seeded unstable resonator and a single stage ofamplification, which provides more than 300 mJ of output energy per pulse. The design is aslightly modified version of an earlier system,7 but the technique may certainly be appliedto virtually any Q- switched resonator.2. SYSTEM DESCRIPTIONThe entire system, illustrated in Fig. 1, consists of five principle stages: masteroscillator, slave oscillator, isolation, amplification and frequency doubling. The masteroscillator is a Lightwave Electronics S -100 Injection Seeding System. It is a compactpackage housing a well -stabilized, laser- diode -pumped, single -mode Nd:YAG ring laser,Faraday isolator and associated electronics, and provides almost 2.5 mW of CW power in a

A fast-locking X-band transmission injection-locked DRO

Abstract: A wideband configuration for a transmission injection-locked (IL) dielectric-resonator oscillator (DRO) is presented. An example of a 9.5-GHz ILDRO with a locking time of less than 100 ns for the final frequency to be within +or-1 p.p.m. of the reference frequency is described. The wideband feature that results from the quadratic coupling configuration used is explained. The effect of the injection gain and resonator Q on the locking time is shown and the isolation of the DRO performance from vibration is demonstrated. >

Analysis of harmonic injection frequency dividers with three-terminals devices

Abstract: This paper presents a method for analysing harmonic injection frequency dividers, one that can be used to determine the locking range with any injection power. The method is proved, with an example in which an analysis is made of a divider by three constructed with a GaAs MESFET. Certain conclusions on design are also included.