Method and apparatus for stabilizing electromagnetic radiation from an optical oscillator - Patents.com

Abstract

To provide a method or a device (especially, a controller) for stabilizing electromagnetic emission from an optical oscillator, especially, a laser, for example, a diode laser having an external resonator.SOLUTION: Stabilization of first electromagnetic emission of an optical oscillator comprises: measuring a deviation of the first electromagnetic emission of the optical oscillator from a standard to generate a first deviation signal; controlling a first controller with the first deviation signal and thus controlling at least one first manipulated variable between at least two manipulated variables, so that the first deviation signal is set, wherein the first manipulated variable is controlled with a first output signal of the first controller, and the first manipulated variable exerts an influence on the first electromagnetic emission of the optical oscillator. Then a modulation signal is generated by a modulation unit to control the first or a second manipulated variable with the modulation signal, the first output signal of the first controller is demodulated with the modulation signal to generate a second deviation signal with respect to a fixed value, and a second controller is controlled with the second deviation signal to control one of the manipulated variables with an output signal of the second controller, so that the second deviation signal is set.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to Claims 1, 23 and 25 The present invention relates to a method and a device (in particular a control device) for stabilizing a first electromagnetic radiation of an optical oscillator, in particular a first laser, each having the features according to the preamble of the present invention. [Background technology]

[0002] Methods or devices of the above mentioned type, in particular control devices, are often used in spectroscopic measurement methods, such as atomic or molecular absorption spectroscopy, or in medical methods. Here, it is desired to generate electromagnetic radiation with at least a minimal wavelength or frequency deviation from a reference. It is of particular interest to further improve already existing methods or devices, in particular control devices, in order to achieve a better stabilization of the electromagnetic radiation of optical oscillators, in particular lasers. It is also a goal to achieve the simplest implementation for this purpose, in order to allow the most general benefit.

[0003] For example, non-patent document 1 describes a method of achieving stabilization of the diode laser radiation by adjusting the operation amount of a diode laser, measuring the intensity or frequency noise of the electromagnetic radiation of the diode laser, and controlling the operation amount to control the intensity or frequency noise.

[0004] Patent Documents 1 and 2 describe adjusting the operation amount of a laser, measuring the light intensity, and controlling the laser to maximize the light intensity.

[0005] US Pat. No. 5,399,433 describes the control of the transmission of a laser in order to achieve stabilization of the laser emission. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US 2009 / 0262762 A1 [Patent Document 2] US 6,687,269 B1 [Patent Document 3] US 2008 / 0159340 A1 [Non-patent literature]

[0007] [Non-Patent Document 1] Chiow et al. "Extended-cavity diode lasers with tracked resonances," Applied Optics, Volume 46, page 7997, publication year 2007 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the invention is to provide a method or device, in particular a control device, for stabilizing the electromagnetic radiation of an optical oscillator, in particular a laser (e.g. a diode laser with an external resonator). The method and device, in particular the control device, respectively, provide particularly stable potentials for generating radiation with at least one wavelength or frequency that is as constant as possible with respect to a reference, and to avoid mode jumps, in particular of the laser (e.g. a diode laser with an external resonator). [Means for solving the problem]

[0009] This object is achieved according to the present invention by Claims 1 and 25 and Claim 23 The present invention is addressed by an apparatus, in particular a control device, for stabilizing the electromagnetic radiation of an optical oscillator, in particular a laser, as described in the above document.

[0010] The technical effect achieved herein is to provide improved stabilization of electromagnetic radiation from optical oscillators, particularly lasers.

[0011] Preferably, one of the plurality of manipulated variables may be controlled by an output signal of the controller, and a deviation signal of the frequency or phase of the electromagnetic radiation of the optical oscillator may be controlled.

[0012] Preferably, the ratio of the modulation indexes, in particular frequency or phase modulation indexes, of at least two manipulated variables may be measured, and a deviation signal may be generated from the deviation of the ratio from a fixed value, and one of the manipulated variables may be controlled by an output signal of the controller to control the deviation signal or the ratio. In this way, conditions may be created to provide a dynamic range for at least one manipulated variable of the optical oscillator.

[0013] More preferably, the frequency or phase modulation index of at least one manipulated variable may be measured, and a deviation signal may be generated from the deviation of the frequency or phase modulation index from a fixed value, and the manipulated variable may be controlled by the output signal of the controller to set the deviation signal. In this way, conditions may be created to provide a dynamic range for at least one manipulated variable of the optical oscillator.

[0014] The modulation index is to be understood as the ratio between the control of the manipulated variable and its effect on the electromagnetic radiation. Correspondingly, the frequency modulation index is to be understood as the control of the manipulated variable and its effect on the frequency of the electromagnetic radiation. Correspondingly, the phase modulation index is to be understood as the control of the manipulated variable and its effect on the phase of the electromagnetic radiation.

[0015] Advantageously, by controlling the ratio between the modulation index of the second manipulated variable and the modulation index of the first manipulated variable, a wide dynamic range for frequency or phase control of the optical oscillator can be provided, and thus improved stabilization of the electromagnetic radiation of the optical oscillator, in particular of the laser, can be achieved.

[0016] In the following, electromagnetic radiation, for example generated by lasers or different reference sources, but also by other sources or generators capable of generating electromagnetic radiation, may comprise at least one frequency or equivalently at least one wavelength, and the electromagnetic radiation may comprise at least one phase. Thus, when it is mentioned to generate a difference between different electromagnetic radiations, it is meant here that a frequency difference and / or a phase difference is generated. Thereby, electromagnetic radiation may be generated that may comprise at least the aforementioned frequency difference and / or phase difference. When it is mentioned to adjust electromagnetic radiation, it may particularly mean here that the frequency and / or phase of the electromagnetic radiation is adjusted. However, it may also mean an adjustment of the amplitude of the electromagnetic radiation, in particular an adjustment of the field quantity or power, the field quantity may comprise a voltage, a current, an electric field or a magnetic field.

[0017] Controlling the electromagnetic radiation may correspondingly include controlling at least one frequency or at least one wavelength, and / or may further include controlling at least one phase.

[0018] Further below, the concepts of wavelength and frequency are used, taking into account that wavelength and frequency have a fundamental relationship with each other, according to which the product of wavelength and frequency corresponds to a speed, where the speed may be the speed of light. Here, the speed of light may be the speed of light in a vacuum or the speed of light in a medium. The medium is characterized by a refractive index, and the speed of light in the medium may be slower than the speed of light in a vacuum. The slowness of the speed of light in a medium relative to the speed of light in a vacuum may be quantified by dividing the speed of light in a vacuum by the refractive index.

[0019] Preferably, all manipulated variables provided in the device according to the invention, in particular in the control device, and in the method according to the invention, may each be controlled by at least one controller, even if this is not explicitly mentioned. The manipulated variables may generally be controlled by a plurality of control signals, in particular by one or more controllers. When controlling the manipulated variables with a plurality of control signals, the control signals may be superimposed, in particular additive. Thus, in particular, any provided manipulated variable may be used to stabilize the electromagnetic radiation of an optical oscillator, in particular a laser. The control may be direct, but also indirect, for example via a second control of other components of the device or method. The manipulated variables may generally be configured to influence the electromagnetic radiation in order to adjust the electromagnetic radiation. In particular, the manipulated variables may be configured to influence the frequency and / or phase of the electromagnetic radiation in order to adjust the frequency and / or phase of the electromagnetic radiation.

[0020] Preferably, the method according to the invention for stabilizing the first electromagnetic radiation of an optical oscillator, in particular a first laser, comprises measuring a deviation between the first electromagnetic radiation of the optical oscillator and a reference and generating a first deviation signal, and may further comprise controlling a first controller with the first deviation signal and controlling at least a first of at least two manipulated variables to adjust the first deviation signal, where the first manipulated variable may be controlled by a first output signal of the first controller, which may affect the first electromagnetic radiation of the optical oscillator, generating a modulation signal with a modulation unit and controlling the first or second manipulated variable with the modulation signal, demodulating the first output signal of the first controller with the modulation signal to generate a second deviation signal relative to a fixed value, controlling the second controller with the second deviation signal and controlling one of the manipulated variables with the output signal of the second controller to set the second deviation signal.

[0021] As described above, controlling at least a first manipulated variable of the at least two manipulated variables to set the first error signal may include controlling with one or more control signals.

[0022] In one embodiment, the method may include setting a first deviation signal by controlling at least two manipulated variables, each of which may be controlled by at least one output signal of a first controller, and the two manipulated variables may act on a first electromagnetic radiation of the optical oscillator. In a preferred embodiment, the deviation may be minimized.

[0023] In a preferred embodiment, the reference may include a second electro-magnetic radiation from a second laser, and the deviation may be obtained as the difference between the first and second electro-magnetic radiation.

[0024] In a preferred embodiment, the reference may include a radio frequency reference and a second electro-magnetic radiation of a second laser, and the deviation may be obtained as the difference of the radio frequency reference relative to the difference between the first and second electro-magnetic radiation.

[0025] In a preferred embodiment, the deviation may include a frequency deviation or a phase deviation.

[0026] In one embodiment, the second laser may be a continuous wave laser. The second laser may be configured as a Sagnac laser. In one embodiment, the second laser may be a pulsed laser. In one embodiment, the second laser may be a frequency comb laser. In one embodiment, the second electro-magnetic radiation may be a frequency comb generated by electro-optic modulation. In one embodiment, the second electro-magnetic radiation may be a frequency comb generated by non-linear frequency conversion.

[0027] In a preferred embodiment, the reference may include a resonator and the deviation may include a frequency or phase deviation between a frequency or phase of the first electro-magnetic radiation and a frequency or phase of the resonator.

[0028] In a preferred embodiment, the resonator may include a quality factor in the range between 10000 and 1000000, which may be equal to the frequency of the resonator divided by the frequency bandwidth of the resonator. Preferably, the resonator may include a ULE (ultra-low expansion) spacer.

[0029] Advantageously, the resonator may include a quality in the range between 50000 and 700000, which quality may be equal to the frequency of the resonator divided by the frequency bandwidth of the resonator, and the resonator may preferably include a ULE (Ultra Low Expansion) spacer. Even more advantageously, the resonator may include a quality in the range between 100000 and 500000. Even more advantageously, the resonator may include a quality in the range between 300000 and 500000.

[0030] In a preferred embodiment, the resonator may include an etalon. The etalon may be configured and designed differently depending on its function in the method and / or the resonator. In particular, the etalon may be a Fabry-Perot etalon.

[0031] In a preferred embodiment, the resonator may include an interferometer.

[0032] The interferometer may be configured as a fiber interferometer, in particular a fiber free-space interferometer. The interferometer may be configured as a free beam interferometer. The interferometer may be configured as a Fizeau interferometer. The interferometer may be configured as a Fabry-Perot interferometer. The interferometer may be configured as a Sagnac interferometer. The interferometer may be configured as a Michelson interferometer, which may include two interferometer arms of different lengths, in particular different optical or geometric lengths.

[0033] In a preferred embodiment, the reference may comprise an atomic or molecular gas and the deviation may comprise a frequency or phase deviation between a frequency or phase of the first electromagnetic radiation and a frequency or phase of a resonance of the atomic or molecular gas. Measuring the frequency or phase deviation may comprise saturation spectroscopy or Ramsey spectroscopy.

[0034] In one embodiment, the reference may include an atomic beam or an atomic beam interferometer, and the deviation may include a frequency or phase deviation between a frequency or phase of the first electromagnetic radiation and a frequency or phase of a resonance of the atomic beam or atomic beam interferometer.

[0035] In one embodiment, the reference may include laser-cooled atoms or ions and the deviation may include a frequency or phase deviation between a frequency or phase of the first electromagnetic radiation and a frequency or phase of a resonance of the atoms or ions.

[0036] In a preferred embodiment, the reference may include a frequency or phase measuring instrument, in particular a wavemeter or interferometer, and the deviation may include a frequency deviation or a phase deviation between the frequency or phase of the first electromagnetic radiation and the frequency or phase of the frequency or phase measuring instrument.

[0037] In a preferred embodiment, the optical oscillator comprises a manipulated variable, which may comprise a semiconductor laser, in particular a diode laser, and the manipulated variable may comprise a diode current of the diode laser and / or a diode temperature of the diode laser. The manipulated variable may be a parameter or an actuator.

[0038] The diode laser may comprise an external resonator. The frequency and / or phase of the first electro-magnetic radiation may be stabilized to a reference frame. The reference frame may include an optical oscillator, which may be implemented as a reference component.

[0039] The first electromagnetic radiation of the external cavity diode laser may be stabilized to a reference frame by the electromagnetic radiation of the frequency comb.

[0040] The diode laser may include a laser diode, and the laser diode may include an anti-reflective coating. The anti-reflective coating may be 1×10 -5 From 1×10 -1 The anti-reflective coating may include a reflectance ranging between 1×10 -3 From 1×10 -1 The reflectance may range between 0.01 and 0.1.

[0041] The diode laser may include a laser diode, and the laser diode may be configured without an anti-reflective coating.

[0042] In one embodiment, the optical oscillator may include a distributed Bragg reflector (DBR) or a distributed feedback (DFB) semiconductor laser. In one embodiment, the optical oscillator may include an optically pumped semiconductor laser, and the manipulated variable may include an optical output of the pump laser. In particular, the optically pumped semiconductor laser may be a vertical external cavity surface emitting laser (VECSEL). In one embodiment, the optical oscillator may be implemented as an optical integrated circuit in one or more semiconductor devices. In one embodiment, the optical oscillator may be implemented as a heterogeneous integrated optical circuit in multiple semiconductor devices.

[0043] In a preferred embodiment, the optical oscillator may comprise a semiconductor laser, which may emit electromagnetic radiation, which may comprise a wavelength between 350 nm and 10 microns, in particular between 350 nm and 1500 nm, in particular between 350 nm and 550 nm, in particular between 600 nm and 800 nm.

[0044] In a preferred embodiment, the optical oscillator may include a first surface and a second surface, at least one of the first surface and the second surface may be partially transparent to the first electro-magnetic radiation, and the optical oscillator may include a tunable wavelength filter for selecting at least one wavelength of the first electro-magnetic radiation.

[0045] In a preferred embodiment, the manipulated variable may comprise at least one piezo actuator, which may be coupled to the first surface and / or the second surface for exerting a force on the first surface and / or the second surface to adjust the frequency or phase of the first electro-magnetic radiation. In particular, the piezo actuator may be configured to provide continuous adjustment of the frequency or phase of the first electro-magnetic radiation. In an embodiment, the manipulated variable may comprise a tunable wavelength filter, and may be configured to tune the tunable wavelength filter.

[0046] In one embodiment, the manipulated variable may include at least one electro-optic modulator that may be placed in a beam path of the laser to adjust the frequency or phase of the first electro-magnetic radiation, hi one embodiment, at least one of the manipulated variables may be external to the optical oscillator and may include an acousto-optic modulator or a frequency shifter.

[0047] Preferably, the device according to the invention for stabilizing the first electromagnetic radiation from an optical oscillator, in particular from a first laser, may comprise a control device.

[0048] Preferably, the control device may include a measurement device, a reference generator for generating a reference, a first controller, and a second controller. In particular, the measurement device may be configured to measure a deviation between a first electromagnetic radiation of the optical oscillator and the reference, and the first controller may be configured to be controlled by a first deviation signal and to control or regulate the deviation signal by controlling at least a first manipulated variable of the at least two manipulated variables with a first output signal.

[0049] Preferably, the control device may include a modulation unit, which may be configured to control the first or second manipulated variable with a modulated signal.

[0050] Preferably, the control device may include a demodulation unit which may be configured to demodulate the first output signal of the first controller with the modulated signal and generate a second deviation signal from a fixed value.

[0051] Preferably, the second controller is controlled by the second error signal and may be configured to control one of the manipulated variables with the output signal so as to control or regulate the second error signal.

[0052] The invention may include a method for stabilizing a first electromagnetic radiation of an optical oscillator, in particular a laser, which may comprise measuring a deviation between the first electromagnetic radiation of the optical oscillator and a reference and generating a first deviation signal. The method may comprise controlling a first controller with the first deviation signal. The method may comprise controlling or adjusting the first deviation signal by controlling at least a first manipulated variable of at least two manipulated variables, the first manipulated variable may be controlled by a first output signal of the first controller, the first manipulated variable may act on the first electromagnetic radiation of the optical oscillator. In particular, the method may comprise measuring a modulation index of at least one of the manipulated variables, in particular a frequency and / or phase modulation index. The method may comprise generating a second deviation signal from a deviation of the modulation index from a fixed value. The method may comprise controlling a second controller with the second deviation signal. The method may comprise controlling one of the manipulated variables with an output signal of the second controller. The method may include controlling or adjusting the second error signal or a modulation index, the modulation index being a ratio between control of at least one of the manipulated variables and an effect of the at least one manipulated variable on the first electromagnetic radiation.

[0053] In one embodiment, the method may include controlling or adjusting the first deviation signal by controlling at least two manipulated variables, where the two manipulated variables may each be controlled by an output signal of a first controller, and where the two manipulated variables may act on a first electromagnetic radiation of the optical oscillator.

[0054] The invention may include a method for stabilizing a first electromagnetic radiation of an optical oscillator, in particular a laser, the method comprising measuring a deviation between the first electromagnetic radiation of the optical oscillator and a reference and generating a first deviation signal, further comprising controlling a first controller with the first deviation signal and controlling at least a first manipulated variable of at least two manipulated variables to adjust the first deviation signal, the first manipulated variable may be controlled with a first output signal of the first controller, and the first manipulated variable may act on the first electromagnetic radiation of the optical oscillator. In particular, the method may include generating a modulation signal with a modulation unit and controlling the first or second manipulated variable with the modulation signal, further comprising measuring a ratio from controlling the manipulated variables, generating a second deviation signal from a deviation of the ratio from a fixed value, controlling the second controller with the second deviation signal, controlling one of the manipulated variables with the output signal of the second controller and adjusting the second deviation signal or the ratio.

[0055] The method according to the invention may comprise generating by the comparison unit a phase deviation signal and / or a frequency deviation signal between a difference between the electromagnetic radiation of the optical oscillator and the electromagnetic radiation of a first reference source and the electromagnetic radiation of a second reference source, and may also comprise coupling the phase deviation signal and / or the frequency deviation signal to a first controller, controlling at least a first manipulated variable of the optical oscillator with at least an output signal of the first controller to adjust the phase deviation signal and / or the frequency deviation signal, generating at least one first superposition of the modulation with an output signal of a second controller, controlling at least one second manipulated variable of the optical oscillator different from the first manipulated variable with the at least one first superposition, generating a demodulated signal of the output signal of the first controller, controlling at least one first manipulated variable of the optical oscillator with a second superposition different from the output signal of the first controller and an output signal of a third controller controlled with the demodulated signal, and controlling a ratio between controlling the at least second manipulated variable with the at least one first superposition and controlling the at least one first manipulated variable with the second superposition.

[0056] Advantageously, generating the phase deviation signal and / or the frequency deviation signal by the comparison unit may comprise a known apparatus and / or a known method for generating a phase deviation signal and / or a frequency deviation signal.

[0057] Advantageously, the method may include minimizing a phase deviation of a phase deviation signal and / or a frequency deviation of a frequency deviation signal between a difference between the electromagnetic radiation of the optical oscillator and the electromagnetic radiation of a first reference source and the electromagnetic radiation of a second reference source.

[0058] Optionally, the method for stabilizing the electromagnetic radiation of an optical oscillator, in particular a laser, may comprise a side-of-fringe locking frequency stabilization, where at least one frequency of the laser may be detuned with respect to a resonance frequency of an absorption line of the cavity or of an atom or molecule, and for this purpose the cavity may be provided with a first input and a first output, or the gas cell may be provided with an atomic or molecular gas and a first input and a first output. Here, the electromagnetic radiation of the optical oscillator, in particular the laser, may be coupled to the first input of the cavity or the first input of the gas cell, and the electromagnetic radiation of the optical oscillator, in particular the laser, coupled from the first output of the cavity or the first output of the gas cell may be detected by a detector. The detector may in particular be a photodetector, and further fluctuations of the at least one frequency of the laser may be converted into intensity fluctuations of an output signal of the detector, in particular the photodetector, and the intensity fluctuations may be minimized by an additionally provided feedback loop. Here, the feedback loop may comprise at least the first manipulated variable or the second manipulated variable, and may further comprise an output signal of the detector, in particular the output of the photodetector.

[0059] Optionally, the method of stabilizing the electromagnetic radiation of an optical oscillator, in particular a laser, may comprise a top-of-fringe locking frequency stabilization, and at least one frequency of the laser may be modulated with a modulation frequency. The electromagnetic radiation of the laser may further be detected by a detector, in particular a photodetector, at the input of the detector, in particular a photodetector, and the modulation of the at least one frequency of the laser may likewise modulate the output signal of the detector, in particular a photodetector. In this case, the output signal of the detector, in particular a photodetector, may in particular be modulated with a modulation frequency, and at least one frequency of the laser is also modulated with this modulation frequency. In order to generate a differential value (derivative) of the signal that may be generated by the electromagnetic radiation of the laser at the input of the detector, in particular a photodetector, the modulation of the output signal of the detector, in particular a photodetector, may further be demodulated with the modulation frequency, and at least one frequency of the laser is also modulated with this modulation frequency.

[0060] The modulation of the frequency of at least one of the lasers can result in a positive or negative value of the derivative, and the top-of-fringe locking frequency stabilization can be configured to minimize the magnitude of the value of the derivative. Preferably, the top-of-fringe locking frequency stabilization can further include a feedback loop, the feedback loop can include an input and an output, the positive or negative value of the derivative can be coupled to the input of the feedback loop, and the output of the feedback loop can adjust the first manipulated variable and / or the second manipulated variable to minimize the magnitude of the value of the derivative.

[0061] In an advantageous embodiment of the method, the optical oscillator may comprise a semiconductor laser, in particular a diode laser.

[0062] The diode laser may include a laser diode, which may or may not include an anti-reflective coating.

[0063] Advantageously, the semiconductor laser may include a first surface and a second surface.

[0064] Furthermore, electromagnetic radiation may be coupled out of the first surface and / or the second surface of the semiconductor laser, or electromagnetic radiation may be at least partially coupled out of the first surface and / or the second surface of the semiconductor laser.

[0065] Advantageously, the electromagnetic radiation may be coupled out of the first surface of the semiconductor laser, or the electromagnetic radiation may be at least partially coupled out of the first surface of the semiconductor laser.

[0066] When electromagnetic radiation is coupled out of a first surface of the semiconductor laser, a second surface of the semiconductor laser may be in a reflective configuration.

[0067] In particular, the second surface of the half-waveguide laser may be at least partially transparent to electromagnetic radiation.

[0068] In an advantageous embodiment of the method, the optical oscillator may include a cavity, the cavity may include a first surface and a second surface, and at least the first surface of the cavity may be partially transparent to electromagnetic radiation. However, alternatively, the second surface of the cavity may be partially transparent to electromagnetic radiation. Furthermore, both the first surface and the second surface of the cavity may be partially transparent to electromagnetic radiation.

[0069] In particular, the electromagnetic radiation may include at least one wavelength, and advantageously the length of the cavity may be longer than the at least one wavelength of the electromagnetic radiation.

[0070] In an advantageous embodiment, the optical oscillator may comprise a tunable wavelength filter for selecting at least one wavelength or for selecting at least one frequency of the electromagnetic radiation, which may be formed in the cavity, and the tuning of the tunable wavelength filter may be a further manipulation variable of the optical oscillator. By means of said wavelength filter, at least one desired frequency of the electromagnetic radiation of the laser or semiconductor laser, in particular a diode laser, may be selected or, equivalently, at least one desired wavelength of the electromagnetic radiation of the laser or semiconductor laser, in particular a diode laser.

[0071] Advantageously, the tunable wavelength filter may include a volume holographic Bragg grating (VHBG) and selecting at least one wavelength of the electromagnetic radiation may include tilting the VHBG relative to a propagation direction of the electromagnetic radiation.

[0072] Advantageously, the tunable wavelength filter may comprise a frequency-selective or wavelength-selective grating, and the selection of at least one wavelength of the electromagnetic radiation may be achieved by tilting the frequency-selective grating with respect to the propagation direction of the electromagnetic radiation, or equivalently, the selection of at least one frequency of the electromagnetic radiation may be achieved by tilting the frequency-selective grating with respect to the propagation direction of the electromagnetic radiation.

[0073] Advantageously, the tunable wavelength filter may comprise a dielectric filter and selecting at least one wavelength or selecting at least one frequency of the electromagnetic radiation may comprise tilting the dielectric filter relative to a propagation direction of the electromagnetic radiation.

[0074] In particular, selecting at least one wavelength or at least one frequency of the electromagnetic radiation by means of the tunable wavelength filter may comprise changing the temperature of the tunable wavelength filter to achieve expansion or contraction of the tunable wavelength filter to select at least one wavelength of the electromagnetic radiation, whereby the at least one structure of the tunable wavelength filter may be displaced or deformed, and the length of the at least one structure of the wavelength filter may be adapted to at least one wavelength of the electromagnetic radiation, or the length of the structure of the wavelength filter may be adapted to a half wavelength of the electromagnetic radiation, or the length of the structure of the wavelength filter may be adapted to a quarter wavelength of the electromagnetic radiation. Advantageously, the length of the structure of the wavelength filter may be adapted to any length of the wavelength of the electromagnetic radiation.

[0075] The tuning of the tunable wavelength filter may be one of the manipulated variables of the optical oscillator.

[0076] Advantageously, in the method for stabilizing electromagnetic radiation, the length of the cavity may be adjustable and the first and / or second surface of the cavity may be coupled to an actuator, which may be configured to act on the first and / or second surface to adjust the length and thereby adjust at least one wavelength of the electromagnetic radiation, and the at least second manipulated variable may comprise an actuation of the actuator acting on the first and / or second surface.

[0077] In particular, by adjusting the length of the cavity, the coupling of a semiconductor laser, in particular a diode laser, with the cavity can be adjusted. Here, the semiconductor laser, in particular the diode laser, may excite one or more electromagnetic modes of the cavity at a given length of the cavity. The electromagnetic mode or modes may include at least one wavelength, while the excitation of further wavelengths may be suppressed. In this way, a tuning of at least one wavelength of the electromagnetic radiation can be achieved.

[0078] In particular, the actuator may be based on the piezoelectric effect or may be an electro-optical modulator.

[0079] Preferably, the cavity may be heatable via a temperature element for modifying a length of the cavity by thermal expansion to tune at least one wavelength of the electromagnetic radiation, the thermal expansion of the cavity produced by the temperature element may represent a further manipulation variable of the optical oscillator.

[0080] Preferably, the cavity may be coolable via a temperature element for modifying a length of the cavity by thermal contraction to tune at least one wavelength of the electromagnetic radiation, the thermal contraction of the cavity produced by the temperature element may represent a further manipulation variable of the optical oscillator.

[0081] The temperature element may be arranged to heat only a partial region of the cavity. However, the temperature element may also be arranged to heat the cavity with a temperature that is at least largely uniformly distributed throughout the cavity. The temperature element may include a temperature measuring device for controlling the temperature of the cavity, in particular for stabilizing the temperature of the cavity.

[0082] Advantageously, the semiconductor laser may be electronically pumped by an electric current, whereby changing the absolute value of the electric current may shorten or stretch at least one wavelength of the electromagnetic radiation, and the at least first manipulated variable may comprise the electric current.

[0083] Advantageously, the semiconductor laser is heatable to change the shape of the semiconductor laser in order to tune at least one wavelength of the electromagnetic radiation, and changing the shape of the semiconductor laser can represent another manipulation variable of the optical oscillator.

[0084] In an advantageous embodiment, generating a phase deviation signal and / or a frequency deviation signal by the comparison unit may include at least one wavelength conversion process to generate a frequency difference and / or a phase difference between the electromagnetic radiation of the optical oscillator and the electromagnetic radiation of the first reference source.

[0085] Here, the wavelength conversion process may be realized by an analog mixer.

[0086] Advantageously, the electromagnetic radiation of the first reference source may be generated by a frequency comb.

[0087] In an advantageous embodiment, the electromagnetic radiation of the second reference source may be adjustable and adaptable to the frequency difference and / or phase difference between the electromagnetic radiation of the optical oscillator and the electromagnetic radiation of the first reference source.

[0088] In an advantageous embodiment, the electromagnetic radiation of the second reference source may comprise at least one frequency and the frequency of the electromagnetic radiation of the second reference source may be set in the range of 500 kHz to 10 GHz, preferably in the range of 500 kHz to 1 GHz, preferably in the range of 500 kHz to 3 GHz, preferably in the range of 500 kHz to 5 GHz.

[0089] In an advantageous embodiment, the method according to the invention may be modified, which includes deactivating the second controller to turn off the output signal of the second controller, providing a diode driver, and instead of superimposing the output signal of the third controller on the output signal of the first controller to generate the second superposition, superimposing a modulation on the output signal of the third controller to generate the first superposition, where the output signal of the diode driver may further be superimposed on the output signal of the first controller to control at least one first manipulated variable of the optical oscillator to generate the second superposition. The output signal of the diode driver may be a voltage and / or a current, preferably the output signal of the diode driver may be a voltage pulse and / or a current pulse.

[0090] The device according to the invention may advantageously include a comparison unit including a wavelength converter and a wavelength comparator, and may further include a first reference source, a second reference source, a first controller, and at least a first manipulated variable, the optical oscillator being configured to be controlled by the first manipulated variable, and the comparison unit being configured to generate a phase deviation signal and / or a frequency deviation signal. The wavelength converter is configured to generate a frequency difference and / or a phase difference between the electromagnetic radiation of the optical oscillator and the electromagnetic radiation of the first reference source, and the wavelength comparator compares the frequency difference and / or the phase difference between the electromagnetic radiation of the optical oscillator and the electromagnetic radiation of the first reference source with the frequency and / or phase of the electromagnetic radiation of the second reference source to generate a phase deviation signal and / or a frequency deviation signal. Here, the first controller may further include a modulation unit configured to receive the phase deviation signal and / or the frequency deviation signal and to control the first manipulated variable with at least an output signal of the first controller, to control or adjust the phase deviation signal and / or the frequency deviation signal, to generate a modulation, and may include a first superposition unit configured to generate at least a first superposition of the modulation with an output signal of the second controller. Furthermore, the device according to the invention may include a second manipulated variable, and the optical oscillator may be configured to be controlled by the second manipulated variable, and at least the second manipulated variable may be configured to be controlled by the first superposition. In particular, the device according to the invention may include a demodulation unit that may be configured to generate a demodulated signal from an output signal of the first controller, and the demodulation unit may further be configured to control a third controller with the demodulated signal and generate an output signal of the third controller controlled by the demodulated signal. Preferably, the device according to the invention may include a second superposition unit that may be configured to control at least one first manipulated variable of the optical oscillator with a second superposition, and the second superposition unit may be configured to generate the second superposition from the output signal of the first controller and the output signal of the third controller controlled by the demodulated signal. In particular, the device according to the invention may include a control unit, and the control unit may be configured to control the ratio between controlling the second manipulated variable and controlling the first manipulated variable.

[0091] In an advantageous embodiment of the device, a tunable wavelength filter may be arranged in the oscillator cavity to select at least one wavelength of the electromagnetic radiation, the tunable wavelength filter being a further manipulated variable of the optical oscillator.

[0092] In an alternative advantageous embodiment, the device according to the invention may be modified, the modification of the device according to the invention may include a device not including a second controller and not including an output signal of the second controller, and may further include a diode driver. The diode driver may be configured to generate an output signal, the output signal of the diode driver may include a voltage and / or a current, advantageously the output signal of the diode driver may include a voltage pulse and / or a current pulse. The modification may further include a first superposition unit, the first superposition unit may be configured to superpose the modulation of the modulation unit on the output signal of the third controller to generate at least a first superposition, instead of having the second superposition unit superpose the output signal of the first controller on the output signal of the third controller to generate the second superposition. The modification may further include a second superposition unit, the second superposition unit may be configured to superpose the output signal of the diode driver on the output signal of the first controller to generate the second superposition, in order to control at least one first manipulated variable of the optical oscillator.

[0093] The diode driver may be configured to drive the laser and may be designed as an internal component of the laser, or preferably, the diode driver may be configured as an external component of the laser and may be coupled to the laser via an electronic connection.

[0094] The invention will be explained below with reference to exemplary embodiments shown in the drawings. [Brief description of the drawings]

[0095] [Figure 1] 1 is a schematic diagram of the control of electromagnetic radiation according to a preferred embodiment of the method according to the invention or according to a preferred embodiment of the device according to the invention; [Diagram 2] 1 is a schematic diagram of the control of electromagnetic radiation according to a preferred embodiment of the method according to the invention or according to a preferred embodiment of the device according to the invention; [Diagram 3] 1 is a schematic diagram illustrating the control of electromagnetic radiation according to a preferred embodiment of the method according to the invention or according to a preferred embodiment of the device according to the invention; [Figure 4] 1 is a schematic diagram illustrating the control of electromagnetic radiation according to a preferred embodiment of the method according to the invention or according to a preferred embodiment of the device according to the invention; [Diagram 5] 1 is a schematic diagram illustrating the control of electromagnetic radiation according to a preferred embodiment of the method according to the invention or according to a preferred embodiment of the device according to the invention; [Figure 6] 1 is a schematic diagram illustrating the control of electromagnetic radiation according to a preferred embodiment of the method according to the invention or according to a preferred embodiment of the device according to the invention; [Figure 7] 1 shows a schematic diagram of an optical oscillator having two manipulated variables for generating and stabilizing electromagnetic radiation according to a method according to the invention or by an apparatus according to the invention. [Figure 8] 2 is a schematic diagram showing the control of electromagnetic radiation according to an advantageous embodiment of the method according to the invention or according to an advantageous embodiment of the device according to the invention; [Figure 9] 3 is a schematic diagram showing the control of electromagnetic radiation according to an alternative advantageous embodiment of the method according to the invention or according to an alternative advantageous embodiment of the device according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0096] Corresponding components are provided with the same reference numbers in the figures and in the detailed figure description below. Furthermore, alternative components having corresponding effects, such as components of the methods for stabilizing the electromagnetic radiation of an optical oscillator (particularly a laser) described above and below or components of devices for stabilizing the electromagnetic radiation of an optical oscillator (particularly a laser) described above and below, are considered interchangeable with the same method or device components described above and below.

[0097] FIG. 1 shows a preferred embodiment of the device 1000 according to the invention for stabilizing electromagnetic radiation 1, which may enable a preferred method according to the invention for stabilizing electromagnetic radiation 1 of an optical oscillator 3. The optical oscillator 3 may include a first manipulated variable 5 and a second manipulated variable 7. Furthermore, the optical oscillator 3 may include a cavity 9, which may have a length 11. Such an optical oscillator 3 is shown separately from the device 1000 in FIG. 7 and may be used as such in the device 1000, but optical oscillators 3 of geometrically different arrangements or functionally different arrangements may also be used in the device 1000. In particular, the optical oscillator 3 may be a laser. The optical oscillator 3 may be arranged in the preferred device 1000 according to the invention to generate electromagnetic radiation 1. Here, the optical oscillator 3 may further include a semiconductor laser 13, which may be arranged in an inner region 15 of the cavity 9. In this regard, the semiconductor laser 13 may excite at least one mode of the cavity 9. Furthermore, a measuring device 17 may be provided, which may be configured to receive the electromagnetic radiation 1. The measuring device 17 may be configured in various ways, as will be further explained below.

[0098] Preferably, the measuring device 17 may comprise a reference generator 19 for generating a first reference 21. The first reference 21 may be in the form of a signal, in particular a reference signal 21. The reference signal 21 may comprise a frequency and / or a phase.

[0099] More preferably, the measuring device 17 may be configured as an independent measuring device for the electromagnetic radiation 1, in which case the measuring device 17 may be configured as described below.

[0100] If the measuring device 17 is configured as an independent measuring device, i.e. there is no reference generator 19, the reference signal may be generated inside the measuring device 17. To this end, the measuring device 17 configured as an independent measuring device may comprise a second reference 23 as a physical component. The second reference 23 as a physical component may be a measuring instrument or a further component for analysing, measuring or processing the electromagnetic radiation 1.

[0101] In this respect, when the measuring device 17 is implemented as a stand-alone measuring device, the measuring device 17 may comprise various frequency selective elements, in particular the various frequency selective elements may individually or in combination form as physical components the aforementioned second reference 23. Advantageously, the various frequency selective elements may comprise a resonator 25, more advantageously an atomic or molecular gas 27, or even more advantageously a frequency or phase meter 29, in any configuration but adapted to function within the device 1000, in particular a wavemeter 31 or an interferometer 33.

[0102] In particular, the frequency stabilisation described above may involve a resonator 25 , an atomic or molecular gas 27 or a frequency or phase measuring device 29 , in particular a wavemeter 31 or an interferometer 33 .

[0103] Preferably, the measuring device 17 may be configured to generate a phase deviation signal 35 and / or a frequency deviation signal 37 by comparing the phase or the frequency of the electromagnetic radiation 1, in particular the electromagnetic radiation 3, with a first reference 21 and / or a second reference 23. The second reference 23 may here comprise a characteristic frequency 39, such as for example a resonant frequency 41 of the resonator 25.

[0104] Advantageously, the phase deviation signal 35 and / or the frequency deviation signal 37 may be a signal that may be proportional to a difference 43 between the electromagnetic radiation 1 and the first reference 21 or the second reference 23, in particular the difference 43 may be defined between the electromagnetic radiation 1 and the reference signal 23 or the characteristic frequency 39. Advantageously, the phase deviation signal 35 and / or the frequency deviation signal 37 may be a signal that may be proportional to a difference 38, which may be defined by taking the difference between the electromagnetic radiation 1 and the first reference 21 and subtracting the difference between the electromagnetic radiation 1 and the first reference 21 from the reference 23. The signal that is proportional to the difference 38 is also referred to as the first deviation signal 38. In an embodiment, the signal that is proportional to the difference 43 may be considered as the first deviation signal 38. The difference 38 and the difference 43 may be electromagnetic radiation signals and each may include a frequency and a phase.

[0105] The reference signal 23 may include a frequency and / or a phase, and the characteristic frequency 39 may also include a phase. Also, a difference may be obtained between the electromagnetic radiation 1 and a frequency dependent quantity 45 of the first reference 21 or the second reference 23. The phase deviation signal 35 and / or the frequency deviation signal 37 may include a difference 38, and in some embodiments may include a difference 43, so that the phase deviation signal 35 and / or the frequency deviation signal 37 can be considered as a first deviation signal 38.

[0106] In a preferred embodiment, the measurement device may include a first input 47, a second input 49, and a first output 51, where the electromagnetic radiation 1 may be coupled to the first input 47, the reference signal 21 may be coupled to the second input 49, and the phase deviation signal 35 and / or the frequency deviation signal 37 may be output at the first output 51.

[0107] The phase deviation signal 35 and / or the frequency deviation signal 37 may be coupled to a third input 53 of the first controller 55. Depending on the form of the phase deviation signal 35 and / or the frequency deviation signal 37, the first controller 55 may generate at least one output signal 57 for controlling a control loop 59. Here, the output signal 57 may drive or control the manipulated variable 5, which may act on the optical oscillator 3 and thus on the electromagnetic radiation 1 for adjusting the electromagnetic radiation 1. In particular, the controller 55 may generate the output signal 57 for controlling a further controller when the difference 43 indicates that the electromagnetic radiation 1 deviates from the reference 21 (in particular the reference signal 21) or when the difference 43 indicates that the electromagnetic radiation 1 deviates from the reference 23 (in particular the characteristic frequency 39). In an advantageous embodiment, the controller 55 may generate the output signal 57 for controlling a further controller when the difference 38 indicates that the difference between the electromagnetic radiation 1 and the first reference 21 deviates from the reference 23.

[0108] The electromagnetic radiation 1 does not have to match the reference exactly, but deviations from a certain offset value of the electromagnetic radiation 1 with respect to the reference may also be taken into account. The controller 55 may generate at least the output signal 57 if the difference 43 indicates that the electromagnetic radiation 1 deviates from the reference 23, in particular from the characteristic frequency 39, or deviates from the reference 21. In an embodiment, the controller 55 may generate at least the output signal 57 when the difference 38 indicates that the difference between the electromagnetic radiation 1 and the first reference 21 deviates from the reference 23. This is particularly true when the difference 43 indicates that the electromagnetic radiation 1 does not deviate from the reference 21, in particular from the reference signal 21, or when the difference 43 indicates that the electromagnetic radiation 1 does not deviate from the reference 23, in particular from the characteristic frequency 39. The output signal 57 may comprise a finite value, in particular a finite amplitude, but the output signal 57 may be zero. The output signal 57 may be an electromagnetic signal or may comprise a constant current or a constant voltage, where the constant current may be 0 amperes and the constant voltage may be 0 volts. The output signal 57 may be coupled to a demodulation unit 61. Furthermore, a modulation unit 63 may be provided for generating a modulation signal 65. The modulation signal 65 may be provided to the demodulation unit 61 to generate a second signal 71 indicative of a deviation from a fixed value 73 at a second output 69. The second deviation signal 71 may be provided to a second controller 74, which generates an output signal 75, which together with the modulation signal 65 may control a second manipulated variable 7. In particular, the second manipulated variable 7 may act on the optical oscillator 3 to adjust the electromagnetic radiation 1, and thus on the electromagnetic radiation 1. In particular, the two manipulated variables 5 and 7 may act together on the optical oscillator 3 to adjust the electromagnetic radiation 1, and thus on the electromagnetic radiation 1. Here, the manipulated variable 5 may include a reaction time different from the reaction time of the manipulated variable 7. Here, the reaction time may be the time that elapses between controlling the manipulated variable and the manipulated variable influencing the optical oscillator 3. Also, the reaction time of the manipulated variable 5 may be longer than the reaction time of the manipulated variable 7. In an embodiment, the reaction time of the manipulated variable 7 may also be longer than the reaction time of the manipulated variable 5. In this case, the second deviation signal 71 may be regulated in order to stabilize the first electromagnetic radiation 1.

[0109] In one embodiment according to the general inventive concept described herein in its entirety, a ratio 77 obtained by controlling the manipulated variables 5, 7 may be measured by a measuring device 79. A second deviation signal 81 may be generated from the deviation of the ratio 77 from a fixed value 83. The second deviation signal 81 may be coupled to a second controller 74 such that the second controller 74 generates an output signal 75. The output signal 75 together with the modulation signal 65 may control the second manipulated variable 7. The second deviation signal 71 may be adjusted or the ratio 77 may be adjusted to stabilize the first electromagnetic radiation 1.

[0110] The manipulated variables 5 and / or 7 may be arranged inside the cavity 9, but alternatively outside the cavity 9, as shown in figure 6. Figure 6 shows a further preferred embodiment formed by a device 5000, where the manipulated variables 5 may be arranged outside the cavity 9. The control part of the device 5000, i.e. the whole controller or part of the controller, may be configured as described above or below.

[0111] The manipulated variables or control elements 5 and / or 7 may include different components acting on the optical oscillator 3, for example an electric current 84 which may be provided to operate the semiconductor laser 13, a temperature controller 85 which may be arranged on the optical oscillator 3, or at least one actuator 87 which may be configured to mechanically, in particular slightly, deform the optical oscillator 3.

[0112] The actuator 87 may be configured to adjust the optical path length of the optical oscillator 3. The actuator 87 may be configured as an electro-optical modulator, and a voltage applied to the electro-optical modulator may be configured to act on the electro-optical modulator to adjust the optical path length of the optical oscillator 3.

[0113] Fig. 2 shows another preferred embodiment represented by the device 1500. The embodiment shown in Fig. 2 is based on the embodiment shown in Fig. 1, in which a modulated signal 65 is coupled to the manipulated variable 7 and a second modulated signal 66 is coupled to the manipulated variable 5. The modulated signals 65 and 66 are characterized by a signal characteristic that is opposite in phase to each other. The amplitude of the modulated signal 65 and the amplitude of the modulated signal 66 may be adjusted to set a target state of the electromagnetic radiation 1. In the target state, the electromagnetic radiation may be in an unmodulated state. The phase of the modulated signal 65 and the phase of the modulated signal 66 may be adjusted to adjust a target state of the electromagnetic radiation 1. In the target state, the electromagnetic radiation may be in an unmodulated state.

[0114] In Fig. 3 a further preferred embodiment is shown which is obtained by means of device 2000. In contrast to the embodiment shown in Fig. 1, device 2000 is arranged to couple output signal 75 to manipulated variable 5 for controlling manipulated variable 5 and output signal 57 to manipulated variable 7 for controlling manipulated variable 7.

[0115] The output signal 75 may be coupled to either the manipulated variable 5 or the manipulated variable 7, and the output signal 57 may be coupled to the respective other manipulated variable 5 or 7. In some cases, the output signal 75 and the output signal 57 may be coupled to the manipulated variable 5, and in other cases, the output signal 75 and the output signal 57 may be coupled to the manipulated variable 7. In other cases, the modulated signal 65 may be coupled to the manipulated variable 5 or the manipulated variable 7. In this case, the manipulated variable 5 may have a response time longer than the response time of the manipulated variable 7. However, in one embodiment, the response time of the manipulated variable 7 may also be longer than the response time of the manipulated variable 5. The controller 55 may generate at least one output signal 57 that may be provided to the aforementioned control action. In one embodiment, the controller may include at least two outputs for generating the output signal 57 and the output signal 58 that may be provided to the aforementioned control action. The output signal 58 may be coupled to the manipulated variable 5 to control the manipulated variable 5, and the output signal 57 may be coupled to the manipulated variable 7 to control the manipulated variable 7. In one embodiment, output signal 58 may be coupled to manipulated variable 7 to control manipulated variable 7 and output signal 57 may be coupled to manipulated variable 5 to control manipulated variable 5 .

[0116] In an embodiment in which the manipulated variable 5 has a response time longer than the response time of the manipulated variable 7, the output signal 58 is coupled to the manipulated variable 5 to control the manipulated variable 5, and the output signal 57 is coupled to the manipulated variable 7 to control the manipulated variable 7, the controller 55 may be configured to generate an output signal 58 having a larger amplitude than the output signal 57, in particular the controller 55 may be controlled to generate an output signal 58 having a smaller frequency bandwidth than the output signal 57, in particular the controller 55 may be configured to generate an output signal 58 having a smaller frequency bandwidth than the output signal 57, in particular the controller 55 may be configured to generate an output signal 58 whose amplitude and / or frequency and / or phase change more slowly over time than the output signal 57.

[0117] In an embodiment in which manipulated variable 5 has a response time shorter than the response time of manipulated variable 7, in which output signal 58 is coupled to manipulated variable 5 to control manipulated variable 5 and in which output signal 57 is coupled to manipulated variable 7 to control manipulated variable 7, controller 55 may be configured to generate output signal 58 having a smaller amplitude than output signal 57, in particular controller 55 may be configured to generate output signal 58 having a larger frequency bandwidth than output signal 57, in particular controller 55 may be configured to generate output signal 58 whose amplitude and / or frequency and / or phase change faster over time than output signal 57.

[0118] In an embodiment in which manipulated variable 5 has a response time longer than the response time of manipulated variable 7, in which output signal 57 is coupled to manipulated variable 5 to control manipulated variable 5 and in which output signal 58 is coupled to manipulated variable 7 to control manipulated variable 7, controller 55 may be configured to generate output signal 57 having a larger amplitude than output signal 58, in particular controller 55 may be configured to generate output signal 57 having a smaller frequency bandwidth than output signal 58, in particular controller 55 may be configured to generate output signal 57 whose amplitude and / or frequency and / or phase vary more slowly over time than output signal 58.

[0119] In an embodiment in which manipulated variable 5 has a response time shorter than the response time of manipulated variable 7, in which output signal 57 is coupled to manipulated variable 5 to control manipulated variable 5 and in which output signal 58 is coupled to manipulated variable 7 to control manipulated variable 7, controller 55 may be configured to generate output signal 57 having a smaller amplitude than output signal 58, in particular controller 55 may be configured to generate output signal 57 having a larger frequency bandwidth than output signal 58, in particular controller 55 may be configured to generate output signal 57 which varies more quickly in amplitude and / or frequency and / or phase over time than output signal 58.

[0120] Also, the control sequences or components of the device 1000 already described above may be provided in the device 2000. The control unit of the device 2000, i.e. the whole controller or a part of the controller, may be as described above or below.

[0121] In Fig. 4 a further preferred embodiment is shown, which is obtained by the device 3000. Here, a manipulated variable, for example the manipulated variable 7, may be controlled by the output signal 58. Furthermore, another manipulated variable, for example the manipulated variable 5, may be controlled by the second deviation signal 71 or 81, similarly to the output signal 57. The output signal 75 may be coupled either to the manipulated variable 5 or to the manipulated variable 7, and the output signal 57 may be coupled to the respective other manipulated variable 5 or 7. The control sequences or components of the other embodiments already mentioned above, in particular of the device 1000, may also be provided in the device 3000. The control part of the device 3000, i.e. the whole controller or part of the controller, may be as described above or below.

[0122] The output signal 58 is coupled to a demodulation unit 61. A modulated signal 65 produced in the modulation unit 63 is fed to the demodulation unit 61 to generate a second deviation signal 71 indicative of the deviation from a fixed value 73 at a second output 69.

[0123] The output signal 58 is configured to control another control element, such as manipulated variable 7, that has a larger dynamic range in order to keep the output signal 57 in the center of its dynamic range.

[0124] Controller 55 may generate at least output signal 57 that may be provided to the aforementioned control activities. In one embodiment, the controller may include at least two outputs for generating output signal 57 and output signal 58 that may be provided to the aforementioned control activities. In one embodiment, output signal 58 may be coupled to manipulated variable 5 to control manipulated variable 5, and output signal 57 may be coupled to manipulated variable 7 to control manipulated variable 7. In one embodiment, output signal 58 may be coupled to manipulated variable 7 to control manipulated variable 7, and output signal 57 may be coupled to manipulated variable 5 to control manipulated variable 5.

[0125] In an embodiment in which the manipulated variable 5 has a response time longer than the response time of the manipulated variable 7, the output signal 58 is coupled to the manipulated variable 5 to control the manipulated variable 5, and the output signal 57 is coupled to the manipulated variable 7 to control the manipulated variable 7, the controller 55 may be configured to generate an output signal 58 having a larger amplitude than the output signal 57, in particular the controller 55 may be controlled to generate an output signal 58 having a smaller frequency bandwidth than the output signal 57, in particular the controller 55 may be configured to generate an output signal 58 having a smaller frequency bandwidth than the output signal 57, in particular the controller 55 may be configured to generate an output signal 58 whose amplitude and / or frequency and / or phase change more slowly over time than the output signal 57.

[0126] In an embodiment in which manipulated variable 5 has a response time shorter than the response time of manipulated variable 7, in which output signal 58 is coupled to manipulated variable 5 to control manipulated variable 5 and in which output signal 57 is coupled to manipulated variable 7 to control manipulated variable 7, controller 55 may be configured to generate output signal 58 having a smaller amplitude than output signal 57, in particular controller 55 may be configured to generate output signal 58 having a larger frequency bandwidth than output signal 57, in particular controller 55 may be configured to generate output signal 58 whose amplitude and / or frequency and / or phase change faster over time than output signal 57.

[0127] In an embodiment in which manipulated variable 5 has a response time longer than the response time of manipulated variable 7, in which output signal 57 is coupled to manipulated variable 5 to control manipulated variable 5 and in which output signal 58 is coupled to manipulated variable 7 to control manipulated variable 7, controller 55 may be configured to generate output signal 57 having a larger amplitude than output signal 58, in particular controller 55 may be configured to generate output signal 57 having a smaller frequency bandwidth than output signal 58, in particular controller 55 may be configured to generate output signal 57 having a smaller frequency bandwidth than output signal 58, in particular controller 55 may be configured to generate output signal 57 whose amplitude and / or frequency and / or phase change more slowly over time than output signal 58.

[0128] In an embodiment in which manipulated variable 5 has a response time shorter than the response time of manipulated variable 7, in which output signal 57 is coupled to manipulated variable 5 to control manipulated variable 5 and in which output signal 58 is coupled to manipulated variable 7 to control manipulated variable 7, controller 55 may be configured to generate output signal 57 having a smaller amplitude than output signal 58, in particular controller 55 may be configured to generate output signal 57 having a larger frequency bandwidth than output signal 58, in particular controller 55 may be configured to generate output signal 57 which varies more quickly in amplitude and / or frequency and / or phase over time than output signal 58.

[0129] Fig. 5 shows another preferred embodiment implemented by the device 4000. Here, a third manipulated variable 89 may be provided so that the device 4000 comprises three manipulated variables 5, 7, 89. The control sequences or components of the other embodiments already described above, in particular the device 1000, may also be provided in the device 4000. The control unit of the device 4000, i.e. the whole controller or a part of the controller, may be as described above or below. The modulation signal 65 may be coupled to the third manipulated variable 89, and the output signal 75 may be coupled to the manipulated variable 7. The output signal 57 may be coupled to the manipulated variable 5 or 89. The output signal 58 may be coupled into the manipulated variable 5 or 89. In particular, the three manipulated variables 5, 7, 89 may together influence the optical oscillator 3 and thus influence the electromagnetic radiation 1 in order to adjust the electromagnetic radiation 1. However, the three manipulated variables 5, 7, 89 may also individually or in combination of two manipulated variables influence the optical oscillator 3 and thus influence the electromagnetic radiation 1 in order to adjust the electromagnetic radiation 1.

[0130] Controller 55 may generate at least one output signal 57 that may be provided to the aforementioned control activities. In one embodiment, the controller may include at least two outputs for generating output signal 57 and output signal 58 that may be provided to the aforementioned control activities. Output signal 58 may be coupled to manipulated variable 5 to control manipulated variable 5, and output signal 57 may be coupled to manipulated variable 89 to control manipulated variable 89. In one embodiment, output signal 58 may be coupled to manipulated variable 89 to control manipulated variable 89, and output signal 57 may be coupled to manipulated variable 5 to control manipulated variable 5.

[0131] In an embodiment in which the manipulated variable 5 has a response time longer than the response time of the manipulated variable 89, the output signal 58 is coupled to the manipulated variable 5 to control the manipulated variable 5, and the output signal 57 is coupled to the manipulated variable 89 to control the manipulated variable 89, the controller 55 may be configured to generate the output signal 58 having a larger amplitude than the output signal 57, in particular the controller 55 may be configured to generate the output signal 58 having a smaller frequency bandwidth than the output signal 57, in particular the controller 55 may be configured to generate the output signal 58 having a smaller frequency bandwidth than the output signal 57, in particular the controller 55 may be configured to generate the output signal 58 whose amplitude and / or frequency and / or phase change more slowly over time than the output signal 57.

[0132] In an embodiment in which manipulated variable 5 has a response time shorter than the response time of manipulated variable 89, in which output signal 58 is coupled to manipulated variable 5 to control manipulated variable 5, and in which output signal 57 is coupled to manipulated variable 89 to control manipulated variable 89, controller 55 may be configured to generate output signal 58 having a smaller amplitude than output signal 57, in particular controller 55 may be configured to generate output signal 58 having a larger frequency bandwidth than output signal 57, in particular controller 55 may be configured to generate output signal 58 whose amplitude and / or frequency and / or phase change faster over time than output signal 57.

[0133] In an embodiment in which the manipulated variable 5 has a response time longer than the response time of the manipulated variable 89, the output signal 57 is coupled to the manipulated variable 5 to control the manipulated variable 5, and the output signal 58 is coupled to the manipulated variable 89 to control the manipulated variable 89, the controller 55 may be configured to generate the output signal 57 having a larger amplitude than the output signal 58, in particular the controller 55 may be configured to generate the output signal 57 having a smaller frequency bandwidth than the output signal 58, in particular the controller 55 may be configured to generate the output signal 57 having a smaller frequency bandwidth than the output signal 58, in particular the controller 55 may be configured to generate the output signal 57 whose amplitude and / or frequency and / or phase change more slowly over time than the output signal 58.

[0134] In an embodiment in which manipulated variable 5 has a response time shorter than the response time of manipulated variable 89, in which output signal 57 is coupled to manipulated variable 5 to control manipulated variable 5 and output signal 58 is coupled to manipulated variable 89 to control manipulated variable 89, controller 55 may be configured to generate output signal 57 having a smaller amplitude than output signal 58, in particular controller 55 may be configured to generate output signal 57 having a larger frequency bandwidth than output signal 58, in particular controller 55 may be configured to generate output signal 57 which changes in amplitude and / or frequency and / or phase more quickly over time than output signal 58.

[0135] FIG. 7 shows an embodiment of an optical oscillator 3, which may include a first manipulated variable 5 as well as a second manipulated variable 7, but may also include further manipulated variables, such as the third manipulated variable 89 (not shown in FIG. 7) already described above. Furthermore, the optical oscillator 3 may be surrounded by a cavity 9, which may have a length 11. Here, each component of the optical oscillator 3 may be used in combination with the optical oscillator 3 independently of the other components of the optical oscillator 3. However, two or more components may be used with the optical oscillator 3. The further components of the optical oscillator 3 shown in FIG. 7 are described in connection with the device 6000 shown in FIG. 8. The components of the optical oscillator 3 shown in FIG. 7 may be used in any of the optical oscillators 3 of the embodiments described herein, in particular the optical oscillators 3 of the embodiments shown in FIGS. 1-6 or 9.

[0136] In Fig. 8 an advantageous device 6000 according to the invention for stabilizing electromagnetic radiation 1 from an optical oscillator 3 is shown, which device enables an advantageous method according to the invention for stabilizing electromagnetic radiation 1 from an optical oscillator 3. The optical oscillator 3 shown in Fig. 8 is shown in a simplified embodiment, a detailed embodiment of which is shown in Fig. 7. However, the term "detailed" should not be interpreted as meaning that the optical oscillator shown in Fig. 7 cannot be extended to include additional components, such as additional manipulated variables. The advantageous device 6000 includes additional components, which may also be provided in the devices 1000, 2000, 3000, 4000 and 5000 or may be combined in a modular manner in the devices 1000, 2000, 3000, 4000 and 5000. For example, the semiconductor laser 13 may include additional components and / or one or more filters may be provided in the cavity 9, which will now be explained in more detail.

[0137] Here, the optical oscillator 3 may in particular be a laser. The optical oscillator 3 may be arranged in the device 6000 according to the invention and generate the electromagnetic radiation 1. Here, the optical oscillator 3 may further comprise a semiconductor laser 13, which may comprise a first surface 91 and a second surface 93, which may be arranged in the cavity 9. Adjacent to the first surface 91 of the semiconductor laser 13, a tunable wavelength filter (wavelength tunable filter) 95 may further be arranged, which may also be arranged in the cavity 9.

[0138] The tunable wavelength filter 95 may be a volume holographic Bragg grating (VHBG), and the tunable wavelength filter 95 may be configured to select at least one wavelength of the electromagnetic radiation 1. The selection of the at least one wavelength of the electromagnetic radiation 1 may be achieved by tilting the wavelength filter 95 with respect to the propagation direction of the electromagnetic radiation 1. In an embodiment, the selection of the at least one wavelength of the electromagnetic radiation 1 may be achieved by controlling the temperature of the wavelength filter 95. In this regard, the expansion or contraction of the wavelength filter 95 may be achieved by heating or cooling the wavelength filter 95, thereby resulting in a transmission or reflection characteristic for the electromagnetic radiation 1 of a selected wavelength or of a selected wavelength continuum, the electromagnetic radiation of the selected wavelength or of the selected wavelength continuum being at least partially transmitted by the wavelength filter 95 or at least partially reflected by the wavelength filter 95. In an advantageous embodiment, the wavelength filter 95 may be tilted with respect to the propagation direction of the electromagnetic radiation 1 to create a particularly advantageous alternative for achieving the selection of the at least one wavelength of the electromagnetic radiation 1. The temperature of the wavelength filter 95 may be controlled.

[0139] Alternatively, the tunable wavelength filter 95 may be configured as a frequency selective grating, and the selection of at least one wavelength of the electromagnetic radiation 1 may be achieved by an inclined frequency selective grating inclined with respect to the propagation direction of the electromagnetic radiation 1.

[0140] In an alternative embodiment, the tunable wavelength filter 95 may be implemented as a dielectric filter, and the selection of the at least one wavelength of the electromagnetic radiation 1 may be achieved by an optical path length of the dielectric filter longitudinal with respect to the propagation direction of the electromagnetic radiation 1, and the further selection of the at least one wavelength of the electromagnetic radiation 1 may be achieved by a dielectric filter tilted with respect to the propagation direction of the electromagnetic radiation 1. The optical path length of the dielectric filter may be obtained by tilting or by changing the temperature of the dielectric filter. However, in particular by changing the temperature of the dielectric filter, the dielectric filter may expand or contract, causing the optical path length of the dielectric filter to change longitudinally with respect to the propagation direction of the electromagnetic radiation 1. In particular by changing the temperature, the optical path length of the dielectric filter as well as that of the aforementioned tunable wavelength filter may be changed.

[0141] The actuator 97 may be located adjacent to the tunable wavelength filter 95, or the actuator 97 may be located within the cavity 9. In particular, the cavity 9 or the optical oscillator 3 may be bounded by a first surface 99 and a second surface 101, where the first surface 99 of the cavity 9 and / or the second surface 101 of the cavity 9 may be coupled to the actuator 97, where in the advantageous embodiment of FIG. 8 only the first surface 99 of the cavity 9 is coupled to the actuator 97.

[0142] Furthermore, the first manipulated variable 5 may be a current, in particular a change in current, and the semiconductor laser 13 may be electronically excited by this current. A change in the absolute value of the current that may be provided to excite the semiconductor laser 13 may result in a shortening or lengthening of at least one wavelength of the electromagnetic radiation 1. However, the manipulated variable 5 may also be understood as an externally adjustable current source, in particular a driver, and the manipulated variable 5 may be coupled to the semiconductor laser 13. In particular, the actuator 97 may be based on the piezoelectric effect, which may be activated by a voltage applied from the outside to the actuator 97. Thus, in this case, the manipulated variable 7 may be a voltage source, for example a voltage source, arranged to apply a voltage to the actuator 97. However, the actuator 97 may also be an electro-optical modulator. In this case, the electro-optical modulator may be an optical device based on the electro-optical effect, which may allow to act on the amplitude or the phase of the electromagnetic radiation 1 by a signal applied from the outside to the electro-optical modulator. In this embodiment, the manipulated variable 7 would be represented by a signaling element for controlling the electro-optical modulator.

[0143] Furthermore, a comparison unit 103 may be provided in the device 6000 according to the invention, which may further comprise a wavelength converter 105 and a wavelength comparator 107. The comparison unit 103 may typically comprise a first input 105 for coupling the electromagnetic radiation 1 to the comparison unit 103. Furthermore, the comparison unit 103 may comprise a second input 107 for coupling the electromagnetic radiation 109 from the first reference source 111 to the comparison unit 103. Furthermore, the comparison unit 103 may comprise a third input 113 for coupling the electromagnetic radiation 115 of the second reference source 117. Finally, the comparison unit 103 may comprise a first output 119, from which the phase deviation signal 35 and / or the frequency deviation signal 37 may be coupled out. Here, the phase deviation signal 35 may be generated by a phase detector as already described above. Furthermore, the frequency deviation signal 37 may be generated by an analog mixer as already described above.

[0144] The input 121 may be configured to receive the phase deviation signal 35 and / or the frequency deviation signal 37, and the input 121 may forward the phase deviation signal 35 and / or the frequency deviation signal 37 to the first controller 123 and / or the second controller 125. Further, a control unit 127 may be provided to control the first controller 123 and / or the second controller 125. Further, the first superposition unit 129 may be configured to receive an output signal 131 from the second controller 125.

[0145] Furthermore, the first superposition unit 129 may be configured to combine the output signal 131 of the second controller 125 with the second manipulated variable 7. Thus, in particular, the actuator 97 receives the output signal 131 of the second controller 125 from the manipulated variable 7, The semiconductor laser 13 may be configured to be controlled by a second controller 125, where the manipulated variable 7 in turn controls the actuator 97. The second superimposition unit 133 may be configured to receive the output signal 135 of the first controller 123. Here, the first manipulated variable 5 may be configured to receive the output signal 135 of the first controller 123 via the first superimposition unit 133. Thus, the semiconductor laser 13 may be controlled by the output signal 135 of the first controller 123, in that the output signal 135 of the first controller 123 controls the manipulated variable 5 via the first superimposition unit 133, whereby the manipulated variable 5 can control the semiconductor laser 13.

[0146] Further, a demodulation unit 137 may be provided, which may further be configured to receive the output signal 135 of the first controller 123. Further, a modulation unit 139 may be provided, which may be configured to generate a modulation 141, which may be a time-varying signal. In particular, the first superposition unit 129 may be configured to receive the modulation 141. Advantageously, the first superposition unit 129 may be configured to generate a superposition 143, which may be generated by the first superposition unit 129 from the modulation 141 and the output signal 131 of the second controller 125. In particular, the second manipulated variable 7 is configured to receive the superposition 143. In particular, the actuator 97 may thus be controlled by the second manipulated variable 7 via the superposition 143.

[0147] Furthermore, the demodulation unit 137 may be configured to receive the modulation 141 from the modulation unit 139. Here, the demodulation unit 137 may generate the demodulated signal 145 from the fixed value 146. Furthermore, the apparatus 6000 may include a third controller 147, which may be configured to be controlled by the demodulation signal 145, and further, the third controller 147 may be configured to generate the output signal 149. Finally, the second superposition unit 133 may be configured to receive the output signal 149 from the third controller 147. In particular, the second superposition unit 133 may be configured to generate a second superposition 151, which may be a superposition of the output signal 149 of the third controller 147 and the output signal 135 of the first controller 123.

[0148] In particular, the first manipulated variable 5 may be configured to be controlled by the second superposition 151. Thereby, the semiconductor laser 13 may be controlled by the second superposition 151 via the manipulated variable 5.

[0149] Advantageously, the device 6000 according to the invention may be provided with a temperature element 153, which may be coupled to the cavity 9, in particular the temperature element 153 may be coupled to the outer wall of the cavity 9. In this way the cavity 9 may be heated in order to achieve a change in the length 11 of the cavity 9 by thermal expansion. Thereby at least one wavelength of the electromagnetic radiation 1 may be adjusted. In particular, by heating the cavity 9 by the temperature element 153 towards a temperature of the cavity 9, which may be above room temperature, a temperature stabilization of the cavity 9 and thus of the optical oscillator 3 may be achieved. The temperature element 153 may also comprise a Peltier element, and it would be feasible to cool the cavity 9 in order to achieve a change in the length 11 of the cavity 9 by thermal contraction. The temperature element 153 may represent another manipulated variable / control element and may be controlled by the controller 123 or 125, not explicitly shown in FIG. 8 or FIG. 9. Tunable wavelength filter 95 may represent another manipulated variable and may be controlled by controller 123 or 125, not explicitly shown in FIG.

[0150] In this case, the demodulation signal 145 may be controlled to stabilize the first electro-magnetic radiation 1. The demodulation signal 145 may be a deviation signal from a fixed value 146.

[0151] Fig. 9 shows a further embodiment of the device according to the invention for stabilizing the electromagnetic radiation 1 from an optical oscillator 3. This embodiment is implemented by the device 7000 shown. To reach the advantageous embodiment shown in Fig. 9, the advantageous device 6000 according to the invention of Fig. 8 may be modified, which may include the device 6000 of Fig. 8 without the second controller 123 and without the output signal 131, and may further include a diode driver 155. The diode driver 155 may be configured to generate an output signal 157, which may include a voltage and / or a current. Advantageously, the output signal 157 of the diode driver 155 may include voltage pulses and / or current pulses. Rather than the second superposition unit 133 being adapted to superpose the output signal 135 of the first controller 123 with the output signal 149 of the third controller 147 to generate the second superposition 151, in a variation, the second superposition unit 133 may further include a superposition unit 129 configured to superpose the modulation 141 and the output signal 149 of the third controller 147 to generate at least the first superposition 143. The variation may further include a second superposition unit 133 configured to superpose the output signal 157 of the diode driver 155 with the output signal 135 of the first controller 123 to generate the second superposition 151 to control at least one manipulated variable of the optical oscillator 303.

[0152] Thus, the device 6000 according to the invention for stabilizing the electromagnetic radiation 1 of an optical oscillator 3, in particular a laser, shown in FIG. 8 and described above, can be used to carry out an advantageous method according to the invention for stabilizing the electromagnetic radiation 1 of an optical oscillator 3, in particular a laser.

[0153] In particular, the method may include generating electromagnetic radiation 1 with a semiconductor laser 13, first exciting the electromagnetic radiation 1 in a cavity 9 and selecting at least one wavelength of the electromagnetic radiation 1 by a tunable wavelength filter 95 disposed in the cavity 9. Furthermore, the electromagnetic radiation 1 may be coupled out of a first surface 99 that is partially transparent to the electromagnetic radiation 1 to generate a phase deviation signal 35 and / or a frequency deviation signal 37.

[0154] For this purpose, the electromagnetic radiation 1 may first be coupled to the comparison unit 103, whereupon the electromagnetic radiation 109 of the first reference source 111 may also be coupled to the comparison unit 103 in order to generate at least one frequency difference between the at least one frequency of the electromagnetic radiation 1 and the at least one frequency of the electromagnetic radiation 109 of the first reference source 111. The generation of the at least one frequency difference between the at least one frequency of the electromagnetic radiation 1 and the at least one frequency of the electromagnetic radiation 109 of the first reference source 111 is advantageously made possible by a wavelength converter 105, which may in particular be an analog mixer. To generate the frequency deviation signal 37, a wavelength comparator 107 may be used, where in the case of generating the frequency deviation signal 37 by the wavelength comparator 107, the wavelength comparator 107 may be an analog mixer. For this purpose, the wavelength comparator or analog mixer 107 may generate a further frequency difference between the at least one frequency of the electromagnetic radiation 1 and the at least one frequency of the electromagnetic radiation 109 of the first reference source 111 on the one hand and the at least one frequency of the electromagnetic radiation 115 of the second reference source 117 on the other hand. Finally, the aforementioned further frequency difference between the at least one frequency of the electromagnetic radiation 1 and the at least one frequency of the electromagnetic radiation 109 of the first reference source 111 on the one hand and the at least one frequency of the electromagnetic radiation 115 of the second reference source 117 on the other hand may represent a frequency deviation signal 37. The phase deviation signal 35 may be generated in essentially the same way as the frequency deviation signal 37, although the wavelength comparator 107 may be a digital phase detector as already mentioned above.

[0155] When the controllers 123 and 125 are controlled by the phase deviation signal 35 and / or the frequency deviation signal 37, the controller 123 may generate the output signal 135 and / or the controller 125 may generate the output signal 131 to obtain the superposition 151 and / or the superposition 143, where further the superposition 143 and / or the superposition 151 may be generated by the function of the above-mentioned devices 6000, 7000 to stabilize the electromagnetic radiation 1. The superposition 143 may control the manipulated variable 7, whereas the superposition 151 may control the manipulated variable 5. The manipulated variable 5 may be connected to the semiconductor laser 13 and / or the manipulated variable 7 may be connected to the actuator 97, so that it may be feasible to adjust the actuator 97 and / or the semiconductor laser 13 individually or simultaneously.

[0156] Advantageously, a control unit 127 may further be provided for controlling the ratio between the control of the second manipulated variable 7 and the control of the first manipulated variable 5. In particular, the control unit 127 may control the first controller 123 and / or the second controller 125. For this purpose, the control unit 127 may include a feedback loop, which may be configured to minimize the phase deviation signal 35 and / or the frequency deviation signal 37 or to control the phase deviation signal 35 to at least a fixed value of the phase deviation signal 35 and / or to control the frequency deviation signal 37 to at least a fixed value of the frequency deviation signal 37. For this purpose, the phase deviation signal 35 and / or the frequency deviation signal 37 may be measured by the control unit 127. Furthermore, the control unit 127 may control the first controller 123 and / or the second controller 125 to minimize the phase deviation signal 35 and / or the frequency deviation signal 37 or to control the phase deviation signal 35 and / or the frequency deviation signal 37 to a fixed value.

[0157] Furthermore, the further embodiment of the device 7000 according to the present invention for stabilizing electromagnetic radiation 1 of an optical oscillator 3, in particular a laser, shown in FIG. 9 and described above may be used to implement the embodiment of the method according to the present invention for stabilizing electromagnetic radiation 1 of an optical oscillator 3, in particular a laser.

[0158] In this respect, the method according to the invention, which may be performed by using the device 6000 shown in Fig. 8, may be modified to arrive at a method which may be performed by using the embodiment of the device 7000 shown in Fig. 9. Here, a modification of the method according to the invention may include deactivating the second controller 125 to turn off the output signal 131, providing a diode driver 155, and superimposing a modulation 141 on the output signal 149 of the third controller 147 to generate the first superposition 143, instead of superimposing the output signal 149 of the third controller 147 on the output signal 135 of the first controller 123 to generate the second superposition 151. Here, the output signal 157 of the diode driver 155 may further be superimposed with the output signal 135 of the first controller 123 to generate a second superposition 151 for controlling at least one first manipulated variable 5 of the optical oscillator 3, and the output signal 157 of the diode driver 155 may include a voltage and / or a current, and advantageously, the output signal 157 of the diode driver 155 may include a voltage pulse and / or a current pulse.

[0159] However, the process steps already described above are also applicable to further embodiments of the apparatus 7000 shown in FIG.

[0160] In both the embodiments of apparatus 6000 shown in FIG. 8 and apparatus 7000 shown in FIG. 9, at least actuator 97 may be provided to increase the dynamic range of control, in that it may be provided to achieve large frequency and / or large phase deviations.

[0161] The devices shown in Figs. 8 and 9 may include components, particularly electronic components, including analog circuit components, but they may also include digital circuit components. Similarly, the components may include both analog and digital circuit components. Similarly, the analog circuit components may be replaced by digital circuit components, and vice versa. On the other hand, this may suppress noise in the control operation described above, allowing for a reliable control operation by the device. Thus, the wavelength comparator 107 may be implemented as a digital phase detector, and the wavelength converter 105 may be implemented as a digital mixer instead of an analog mixer. Thus, the wavelength converter 107 and the wavelength comparator 105 may be implemented as a fully digital circuit, for example, on a logic circuit on a single chip, for example, on a field programmable gate array (FPGA) chip. Thus, except for the manipulated variables 5 and 7 and the optical oscillator 3, the control forms described above may be realized by the FPGA chip. However, the logic on the FPGA chip may provide output signals for controlling or regulating the manipulated variables 5 and 7. However, the manipulated variables 5 and 7 may be provided in such a way that they may also be provided by logic circuits on the FPGA chip. The FPGA chip may further include circuitry that may provide an optical interface such that the electromagnetic radiation 107 from the first reference source 111 may be coupled to the FPGA chip and the electromagnetic radiation 1 from the optical oscillator 3 may be coupled to the FPGA chip. For example, the second reference source 117 may be a voltage controlled oscillator. The aforementioned form of control is not limited to a semiconductor laser but may be any oscillator with a controllable output signal or providing another controllable signal for stabilization. [Explanation of symbols]

[0162] 1. Electromagnetic radiation 3. Optical Oscillator 5 (1st) Manipulated amount 7 (2nd) Manipulated amount 9 Cavity 13 Semiconductor laser 15 Internal area 17 Measuring Equipment 19 Reference generator 21 Reference Signal 23 Reference Signal 25 resonator 27 Atomic or molecular gas 29 Frequency or phase measuring instruments 31 Wavemeter 33 Interferometer 35 Phase deviation signal 37 Frequency deviation signal 38 1st deviation signal (differential) 39 Characteristic Frequency 41 Resonance frequency 43 Difference 45 Frequency Dependence 47 First Input 49 Second Input 51 1st output 53 3rd input 55 (1st) Controller 57 Output Signal 58 Output Signal 59 Control Loop 61 Demodulation Unit 63 Modulation Unit 65 Modulated Signal 66 (2nd) Modulation signal 69 2nd Output 71 Second deviation signal 73 Fixed value 74 Second Controller 75 Output Signal 77 Ratio 79 Measuring Equipment 81 Second deviation signal 83 Fixed value 84 Current 85 Temperature Controller 87 Actuator 89 (3rd) Manipulated amount 91 1st surface 93 Second surface 95 Wavelength Filter 97 Actuator 99 1st surface 101 Second surface 103 Comparison Unit 105 Wavelength converter (first input) 107 Wavelength comparator (second input) 109 Electromagnetic Radiation 111 First reference source 113 3rd input 115 Electromagnetic Radiation 117 Second reference source 119 1st Output 121 Input 123 (1st) Controller 125 (2nd) Controller 127 Control Unit 129 First Superposition Unit 131 Output Signal 133 (2nd) Superposition Unit 135 Output Signal 137 Demodulation Unit 139 Modulation Unit 141 Modulation 143 (1st) Superimposition 145 Demodulated Signal 146 fixed value 147 Third Controller 149 Output Signal 151 (2nd) Superimposition 153 Temperature element 155 Diode Driver 157 Output Signal 1000, 1500, 2000, 3000, 4000, 5000, 6000, 7000 devices

Claims

1. A method for stabilizing a first electromagnetic radiation (1) of an optical oscillator (3), comprising the steps of: - measuring a deviation (35, 37, 43, 38) between the first electromagnetic radiation (1) of the optical oscillator (3) and a reference (21, 23, 39, 41, 115) and generating a first deviation signal (35, 37, 43, 38); controlling a first controller (55, 123) with the first deviation signal (35, 37, 43, 38); controlling the first deviation signal (35, 37, 43, 38) by controlling at least one first manipulated variable (5, 7, 89) of at least two manipulated variables (5, 7, 89), the first manipulated variable (5, 7, 89) being controlled by a first output signal (57, 135) of the first controller (55, 123), the first manipulated variable (5, 7, 89) influencing the first electromagnetic radiation (1) of the optical oscillator (3), generating a modulation signal (65, 141) in a modulation unit (63, 139) and controlling the first or second manipulated variable (5, 7, 89) with the modulation signal (65, 141); demodulating the first output signal (57, 135) of the first controller (55, 123) with the modulation signal (65, 141) to generate a second deviation signal (71, 145) with respect to a fixed value (73, 146); controlling a second controller (74, 147) with the second deviation signal (71, 145); controlling one of the manipulated variables (5, 7, 89) with an output signal (75, 149) of the second controller (74, 147) to control the second error signal (71, 145).

2. the first and second manipulated variables (5, 7, 89) are controlled by the first controller (55, 123), the second controller (74, 147), and the modulation unit (63, 139); 2. The method according to claim 1, characterized in that the deviation (35, 37, 38, 43) is minimized by the first and second manipulated variables (5, 7, 89) influencing the first electromagnetic radiation (1) of the optical oscillator (3).

3. The method according to claim 1, characterized in that the optical oscillator (3) is a first laser (13).

4. generating a second modulation signal (66) in the modulation unit (63) and controlling the other of the first and second manipulated variables (5, 7, 89) with the second modulation signal (66); and adjusting the phase and / or amplitude of the modulation signal (65) and adjusting the phase and / or amplitude of the second modulation signal (66) to provide the first electromagnetic radiation (1) without modulation.

5. In a step of generating a second modulation signal (66) in the modulation unit (63) and controlling the other of the first and second manipulated variables (5, 7, 89) with the second modulation signal (66), 5. The method of claim 4, characterized in that the effects of the modulation signal (65) and the second modulation signal (66) on the first electromagnetic radiation (1) are in phase opposition to each other.

6. 4. The method according to claim 1, wherein the reference (21, 23, 39, 41, 115) comprises a radio frequency reference (159) and a second electromagnetic radiation (161, 109) of a second laser (163, 111), and the deviation (35, 37, 38, 43) is generated as a difference of the radio frequency reference (159) relative to a difference between the first electromagnetic radiation (1) and the second electromagnetic radiation (161, 109).

7. 4. The method according to claim 1, wherein the deviation (35, 37, 38, 43) comprises a frequency deviation (37, 43) or a phase deviation (35, 43).

8. 2. The method of claim 1, wherein the reference (23) comprises a resonator (25) and the deviation (35, 37, 38, 43) comprises a frequency deviation (37, 43) or a phase deviation (35, 43) between a frequency or a phase of the first electromagnetic radiation (1) and a frequency or a phase of the resonator (25).

9. The resonator (25) includes a quality in the range between 10,000 and 1,000,000; 9. The method according to claim 8, characterized in that said quality is equal to the frequency of said resonator (25) divided by the frequency bandwidth of said resonator (25).

10. 10. The method of claim 9, characterized in that the resonator (25) comprises a ULE (ultra-low expansion) spacer.

11. 11. The method according to any one of claims 8 to 10, characterized in that the resonator (25) comprises an etalon.

12. 11. The method according to any one of claims 8 to 10, characterized in that the resonator (25) comprises a Fabry-Perot etalon.

13. 2. The method of claim 1, wherein the reference (23) comprises an atomic or molecular gas (27) and the deviation (35, 37, 38, 43) comprises a frequency deviation (37, 43) or a phase deviation (35, 43) between a frequency or a phase of the first electromagnetic radiation (1) and a frequency or a phase of a resonance of the atomic or molecular gas (27).

14. 2. The method according to claim 1, characterized in that the reference (23) comprises a frequency or phase measurement device (29, 31, 33) and the deviation (35, 37, 38, 43) comprises a frequency deviation (37, 43) or a phase deviation (35, 43) between the frequency or phase of the first electromagnetic radiation (1) and the frequency or phase of the frequency or phase measurement device (29, 31, 33).

15. The method according to claim 14, characterized in that the reference (23) includes a wavemeter (31) or an interferometer (33).

16. 4. The method according to claim 1, wherein the optical oscillator (3) comprises the manipulated variable (5, 7, 89) and comprises a diode laser (13), the manipulated variable comprising a diode current (5, 7, 89) of the diode laser and / or comprising a diode temperature (5, 7, 89) of the diode laser (13).

17. 4. The method according to claim 1, wherein the optical oscillator (3) comprises a first surface (99) and a second surface (101), at least one of the first surface (99) and the second surface (101) being partially transparent to the first electromagnetic radiation (1).

18. The method according to claim 17, characterized in that the optical oscillator (3) is provided with a tunable wavelength filter (95) for selecting at least one wavelength of the first electromagnetic radiation (1).

19. 18. The method according to claim 17, characterized in that the manipulated variable (5, 7, 89) comprises at least one piezo actuator coupled to the first surface (99) and / or the second surface (101) for exerting a force on the first surface (99) and / or the second surface (101) to adjust a frequency or a phase of the first electromagnetic radiation (1).

20. 11. The method according to any one of claims 8 to 10, characterized in that the manipulated variable (5, 7, 89) comprises at least one electro-optical modulator arranged in a beam path of the optical oscillator (3) for adjusting the frequency or phase of the first electromagnetic radiation (1).

21. 18. The method of claim 17, characterized in that the manipulated variable (5, 7, 89) comprises a tunable wavelength filter (95) and is configured to tune the tunable wavelength filter (95).

22. 4. The method according to claim 1, wherein at least one of the manipulated variables (5, 7, 89) is external to the optical oscillator (3) and comprises an acousto-optical modulator or a frequency shifter.

23. A control device (1000, 2000, 3000, 4000, 5000, 6000, 7000) for stabilizing a first electromagnetic radiation (1) of an optical oscillator (3), comprising: A measuring device (17, 107); a reference generator (19, 117) for generating a reference (21, 115); A first controller (55, 123); A second controller (74, 147, 155), the measuring device (17, 107) is configured to measure a deviation (35, 37, 38, 43) between the first electromagnetic radiation (1) of the optical oscillator (3) and the reference (21), The first controller (55, 123, 127) is controlled by a first error signal (35, 37, 43) and is configured to control at least one first manipulated variable (5, 7, 89) of at least two manipulated variables (5, 7, 89) with a first output signal (57, 131, 135, 143, 151) to set the error signal (35, 37, 38, 43), a modulation unit (63, 139) designed to control said first or second manipulated variable (5, 7, 89) with a modulation signal (65, 141); a demodulation unit (61, 137) configured to demodulate the first output signal (57, 135, 131) of the first controller (55, 123) with the modulation signal (65, 141) to generate a second deviation signal (71, 145) relative to a fixed value (73, 146), The second controller (74, 147, 155) is controlled by the second deviation signal (71, 145) and is configured to control one of the manipulated variables (5, 7, 89) with an output signal (75, 149, 157, 151) so as to set the second deviation signal (71, 145).

24. The control device described in Claim 23, characterized in that the optical oscillator (3) is a first laser (13).

25. A method for stabilizing a first electromagnetic radiation (1) of an optical oscillator (3), comprising the steps of: - measuring a deviation (35, 37, 38, 43) between the first electromagnetic radiation (1) of the optical oscillator (3) and a reference (21, 23, 39, 41) and generating a first deviation signal (35, 37, 38, 43); controlling a first controller (55) with the first deviation signal (35, 37, 38, 43); controlling the first deviation signal (35, 37, 38, 43) by controlling at least one first manipulated variable (5, 7, 89) of at least two manipulated variables (5, 7, 89), the first manipulated variable (5, 7, 89) being controlled by a first output signal (57) of the first controller (55), the first manipulated variable (5, 7, 89) influencing the first electromagnetic radiation (1) of the optical oscillator (3), - measuring a modulation index (77) of at least one of said manipulated variables (5, 7, 89) and generating a second deviation signal (81) from the deviation of said modulation index (77) from a fixed value (83); controlling a second controller (74) with the second deviation signal (81); and controlling one of the manipulated variables (5, 7, 89) with an output signal (75) of the second controller (74) to control the second error signal (81) or the modulation index (77), 4. The method of claim 3, wherein the modulation index (77) is a ratio between the control of at least one of the manipulated variables (5, 7, 89) and the effect of the at least one manipulated variable (5, 7, 89) on the first electromagnetic radiation (1).

26. The method of claim 25, wherein the at least one modulation index (77) is a frequency and / or phase modulation index.

27. ​​A method as described in claim 25 or 26, characterized in that the optical oscillator (3) is a first laser (13).

28. 26. The method according to claim 25, characterized in that it comprises the step of generating a modulation signal (65, 141) in a modulation unit (63, 139) and controlling the first or second manipulated variable (5, 7, 89) with said modulation signal (65, 141).

29. generating a second modulation signal (66) in the modulation unit (63) and controlling the other of the first and second manipulated variables (5, 7, 89) with the second modulation signal (66); and adjusting the phase and / or amplitude of the modulating signal (65) and adjusting the phase and / or amplitude of the second modulating signal (66) to provide the first electro-magnetic radiation (1) unmodulated.

30. In the step of generating a second modulation signal (66) in the modulation unit (63) and controlling the other of the first and second manipulated variables (5, 7, 89) with the second modulation signal (66), 30. The method of claim 29, characterized in that the effect of the modulation signal (65) on the first electromagnetic radiation (1) and the effect of the second modulation signal (66) on the first electromagnetic radiation (1) are in anti-phase with each other.

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