Showing papers on "Comb generator published in 2002"

Ultraprecise measurement of optical frequency ratios.

Abstract: We developed a novel technique for frequency measurement and synthesis, based on the operation of a femtosecond comb generator as transfer oscillator. The technique can be used to measure frequency ratios of any optical signals throughout the visible and near-infrared part of the spectrum. Relative uncertainties of 10(-18) for averaging times of 100 s are possible. Using a Nd:YAG laser in combination with a nonlinear crystal we measured the frequency ratio of the second harmonic nu(SH) at 532 nm to the fundamental nu(0) at 1064 nm, nu(SH)/nu(0) = 2.000 000 000 000 000 001x (1 +/- 7x10(-19)).

Control of the frequency comb from a modelocked Erbium-doped fiber laser.

Abstract: We show that a stretched-pulse mode-locked fiber laser produces a well-defined frequency comb, providing a compact source of frequency combs and allowing comb-based optical frequency metrology to be extended into the 1.55 μm region. This is achieved by comparing the frequency doubled output of the fiber laser to that of a mode-locked Ti:Sapphire laser, after the two lasers are synchronized. The offset frequency of the fiber laser frequency comb is found to be highly sensitive to the pump power, which enables the implementation of a feedback loop to control the offset frequency. The resulting RMS frequency jitter of the heterodyne beat signal is 355 kHz (0.5 Hz – 102 kHz BW) for this initial demonstration.

Frequency comb analysis

Abstract: Methods and apparatus for generating a frequency comb and for its use in analyzing materials and in telecommunications. The frequency comb is generated by passing pulsed light from a laser through an optical fiber having a constriction. The frequency comb comprises a plurality of monochromatic components separated in frequency by a substantially constant frequency increment. The monochromatic components are used to probe materials for analysis. In preferred embodiments, the materials are DNA, RNA, PNA and other biologically important molecules and polymers. Optical responses are observed and used to analyze or identify samples. In telecommunication applications, the individual monochromatic components serve as carriers for individual communication channels that can carry information of any of a variety of types, such as voice, data and images.

Phase-coherent synthesis of optical frequencies and waveforms

Abstract: Precision phase control of an ultrawide-bandwidth optical-frequency comb has produced remarkable and unexpected progress in both areas of optical-frequency metrology and ultrafast optics. A frequency comb (with 100 MHz spacing) spanning an entire optical octave (>300 THz) has been produced, corresponding to millions of marks on a frequency “ruler” that are stable at the Hz level. The precision comb has been used to establish a simple optical clock based on an optical transition of iodine molecules, providing an rf clock signal with a frequency stability comparable to that of an optical standard, and which is superior to almost all conventional rf sources. To realize a high-power cw optical frequency synthesizer, a separate, widely tunable single-frequency cw laser has been employed to randomly access the stabilized optical comb and lock to any desired comb component. Carrier-envelope phase stabilization of few-cycle optical pulses has recently been realized. This advance in femtosecond technology is important for both extreme non-linear optics and optical-frequency metrology. With two independent femtosecond lasers, we have not only synchronized their relative pulse timing at the femtosecond level, but have also phase-locked their carrier frequencies, thus establishing phase coherence between the two lasers. By coherently stitching the optical bandwidth together, a “synthesized” pulse has been generated with its 2nd-order autocorrelation signal displaying a shorter width than those of the two “parent” lasers.

Agile spread waveform generator

Abstract: An agile spread spectrum waveform generator comprises a photonic oscillator and an optical heterodyne synthesizer. The photonic oscillator comprises a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier. The optical heterodyne synthesizer includes first and second phase-locked lasers; the first laser feeding the multi-tone optical comb generator and the second laser comprising a rapidly wavelength-tunable single tone laser whose output light provides a frequency translation reference. A photodetector is provided for heterodyning the frequency translation reference with the optical output of the photonic oscillator to generate an agile spread spectrum waveform.

Ultra wideband signal source

Abstract: A master oscillator (100) generates a first tone that has a frequency or notional carrier frequency of the ultra wideband signal. The comb generator (102) has three outputs that correspond to second, third, and fourth tones. After the comb generator (102), the signals pass through filters (122, 132, 142), phase trimmers (124, 134, 144), and amplifiers (116, 126, 136, 146). Finally the tone signals are all put into a combiner network (150).

Agile spread waveform generator and photonic oscillator

Abstract: An agile spread spectrum waveform generator comprises a photonic oscillator and an optical heterodyne synthesizer. The photonic oscillator comprises a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier. The optical heterodyne synthesizer includes first and second phase-locked lasers; the first laser feeding the multi-tone optical comb generator and the second laser comprising a rapidly wavelength-tunable single tone laser whose output light provides a frequency translation reference. A photodetector is provided for heterodyning the frequency translation reference with the optical output of the photonic oscillator to generate an agile spread spectrum waveform.

Optical frequency comb generator using a single-sideband suppressed-carrier modulation in an amplified circulating fiber loop

Abstract: An optical frequency comb generator capable of producing numerous sidebands with a span of over I THz is developed, which is configured as an optical fiber circulating loop, containing a single-sideband suppressed-carrier modulator for wide-band frequency translation, and an optical amplifier. The translator consists of a dual-electrode Mach-Zehnder modulator for sideband suppression and a Sagnac fiber loop interferometer for carrier suppression. Generated comb spectra show that the number of comb-lines observed increases as the loop gain approaches slightly below unity.

Frequency agile spread waveform generator and method and pre-processor apparatus and method

Abstract: A frequency agile spread spectrum waveform generator comprises a photonic oscillator andan optical heterodyne synthesizer. The photonic oscillator comprises a multi-tone opticalcomb generator for generating a series of RF comb lines on an optical carrier. The optical heterodyne synthesizer includes first and second phase-locked lasers; the first laser feedingthe multi-tone optical comb generator and the second laser comprising a wavelength-tunablesingle-tone or multi-tone laser whose output light provides a fequency translation reference.At least one photodetector is provided for heterodyning the frequency translation referencewith the optical output of the photonic oscillator to generate an agile spread spectrum waveform.

Method and apparatus for generating a sequence of optical wavelength bands

Abstract: An optical comb generator includes frequency-shifting elements of a particular type that we refer to as a “frequency mirror.” A frequency mirror mixes input light at a signal frequency and a reference frequency to produce output light at a third frequency that lies in contraposition to the signal frequency relative to the reference frequency. The comb generator includes at least two frequency mirrors, having respective reference frequencies F 1 and F 2 . At least some of the power of a light beam is shifted by the first frequency mirror from an input frequency to a frequency that lies in contraposition thereto relative to F 1 , and then light at the shifted frequency is shifted to yet a new frequency by the second frequency mirror. The resulting twice-shifted frequency lies in contraposition to the once-shifted frequency, relative to F 2 . The result is that a difference of 2(F 2 −F 1 ) separates the twice-shifted frequency from the input frequency. This process is repeatable to generate a comb of equally spaced, shifted frequencies. In specific embodiments of the invention, the frequency mirror is a periodically poled lithium niobate (PPLN) device pumped by laser radiation at the pertinent reference frequency.

System and method for using a saw based RF transmitter for AM modulated transmission in a TPM

Abstract: For use in a tire pressure monitoring system, an amplitude modulation (AM) radio frequency (RF) oscillator includes a modulator and a generator. The modulator may be configured to generate a modulation signal in response to a data input signal. The generator may be configured to generate an AM output signal having an RF carrier frequency and an envelope, wherein the envelope is amplitude modulated by the modulation signal and the generator includes a frequency determining device.

Method and device for determining sideband ratio of superconduction mixer using comb generator

Abstract: A method for determining the sideband ratio of a superconduction mixer using a comb generator. The method is characterized in that (a) the sideband ratio of a mixer for correction of the output of a comb generator is tentatively adjusted, (b) the intensity of a signal of a pseudo−celestial body signal oscillator for correction of the output of a comb generator, (c) steps (a), (b) are repeated to derive the relation between the sideband ratio and the intensity of the pseudo−celestial body signal, (d) the comb generator output is corrected, and (e) the sideband ratio of the mixer to be measured is derived.

110 GHz opto-electronic frequency synthesiser using optical comb generator and uni-travelling-carrier photodiode

Abstract: Using optical comb generation, SG-DBR laser comb line selection and uni-travelling-carrier photodiode, opto-electronic generation of 10 GHz to 110 GHz, -80 dBc/Hz SSB phase noise millimetre wave signals at powers up to 2 mW is demonstrated using no electrical amplification.

A signal generator device, method for generating a signal and devices including such a signal generator device

Abstract: A signal generator device which includes a generator input ( 51 a, 51 b ) for receiving input signals; a frequency multiplication section ( 7 ) including: at least two frequency multiplication inputs ( 551 - 555 ) communicatively connected to the generator input ( 51 a, 51 b ), for receiving each at least one phase shifted signal having a phase difference with respect to the other phase shifted signal; pulse generator sections ( 741 - 745 ) connected to at least one of said frequency multiplication inputs for generating an output signal if said phase shifted signals has a transition from a first state to a second state. The signal generator device further includes at least one generator output ( 72 ) connected to at least one of said at least one pulse generator sections for transmitting said output signal.

System for symmetric pulse generator flip-flop

Abstract: A Symmetric Pulse Generator Flip-Flop (SPG-FF). The flip-flop comprises two pulse generator stages that each respond to one particular transition of an input clock signal. Thus, the flip-flop is triggered on both the rising and falling edge of the clock signal to capture an input data signal. The outputs of the generator stages are combined to form a flip-flop output.

Novel electro-optic sampling system with an optoelectronic phase-locked phase shifter as a delay-time controller

Abstract: An inherently delay-time-tunable pulsed laser diode controlled by a voltage-adjusted optoelectronic phase shifter is employed to realize a novel electro-optic sampling system without use of a conventional opto-mechanic delay line. The maximum scanning speed, time, responsivity, and resolution of the optoelectronic delay line are 100 points/s, 3.6 ns (1.8 periods), 0.54 ns/V, and 0.2 ps, respectively. The waveform-sampling of a sinusoidal signal at 500 MHz and an electrical pulse with 91.5-ps full-width at half-maximum generated from a microwave oscillator and comb generator, respectively, are reported with measurement error of less than 5%.

GaAs Schottky varactor diode optimization for high-performance nonlinear transmission lines

Abstract: Nonlinear transmission lines (NLTLs) using Schottky diodes as varactor loads provide significant performance and efficiency advantages for both frequency multiplication and phase shifting applications that will benefit comb generator and phased array applications, respectively. Prior NLTL optimization has been limited only to analytical studies of specific diode profiles. This paper describes, for the first time, the optimization of NLTL performance through the design, simulation, and fabrication of five different experimental GaAs diode doping profiles. Fabricated device and circuit data from the different wafers are presented and compared. To the knowledge of the authors, these NLTLs demonstrate the least conversion loss for any comb generators driven at 1 GHz.

Phase noise measurement of multiwavelength coherent comb generator

Abstract: We characterize the phase coherence of the longitudinal modes by electric field correlations of the modelocked pulse train. Pulses with arbitrary delay are correlated by using a Michelson interferometer.

An Interferornetric Microwave Comb Generator

Abstract: We have developed a scheme for generating a comb of radio frequencies, covering the microwave to millimeter spectral range. The system utilizes a single diode laser coupled to an optical interferometer and photodetector. Frequency modulating the laser at a rate of 2.154 GHz, we observe an electrical signal from the photodetector with a spectrum that is a comb that extends beyond the 40 th harmonic of the fundamental modulation frequency. The line width of the electrical output is less than 2 Hz. We have compared the phase stability of an element of the comb with the output from a classical diode frequency multiplier (both driven from the same source) and have concluded that a phase-stable output can be generated. Finally, we have developed analytical and numerical models that suggest that our scheme may be used for frequency generation through the submillimeter.

Optical filter and method of filtering

Abstract: The optical filter has a coupler with a number of out put sections. The input signal is a comb spectrum with a periodically spaced waveform. Each output branches coupled to a waveguide with co propagating coupling components in cascade, each section producing a comb spectrum into equal parts for the output sections.

From relative to absolute: optical phase measurement and control in ultrashort pulses

Abstract: Summary form only given. A phase stabilized frequency comb spanning an entire optical octave (>300 THz) has been established, leading to a single step, phase coherent connection between the optical and radiofrequency spectral domains. The precision comb can also serve as an accurate gear-box to transfer the oscillatory information of a laser stabilized by a high quality optical transition down to the microwave/rf domain, thereby establishing a simple optical atomic clock. We present one of the systems based on an optical transition of iodine molecules, providing an rf clock signal with a frequency stability comparable to that of an optical standard, and that is superior to almost all conventional rf sources. To realize a high-power CW optical frequency synthesizer, a separate widely tunable single-frequency cw laser has been employed to randomly access the stabilized optical comb and lock to any desired comb component.