Detailed Office Action
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Information Disclosure Statement Submitted After Notice of Allowance
The Information Disclosure Statement (IDS) filed 22 April 2026 cited El Amili et al. (2022/0190920; “El Amili”) .
Examiner’s Comment – Independent Claims 1 and 24
In this Office Action, independent claims 1 and 24 are rejected under 35 U.S.C. 103 as being unpatentable over El Amili et al. (2022/0190920; “El Amili”) in view of Osipenko et al. (Offset Laser Frequency Stabilization Using Modulation Transfer Spectroscopy. Meas Tech 66, 1–5 (2023); “Osipenko”) and further in view of Burke et al. (10/,684,591; “Burke”).
Request for Continued Examination
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after allowance or after an Office action under Ex Parte Quayle, 25 USPQ 74, 453 O.G. 213 (Comm'r Pat. 1935). Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, prosecution in this application has been reopened pursuant to 37 CFR 1.114. Applicant's submission filed on 22 April 2026 has been entered.
Response to Arguments
Applicant’s arguments with respect to claims 1-17 and 24 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. Specifically, this Office Action’s applies the teachings and disclosures of the IDS filed 22 April 2026.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1, 16-17, and 24
Claims 1, 16-17, and 24 are rejected under 35 U.S.C. 103 as being unpatentable over El Amili et al. (2022/0190920; “El Amili”) in view of Osipenko et al. (Offset Laser Frequency Stabilization Using Modulation Transfer Spectroscopy. Meas Tech 66, 1–5 (2023); “Osipenko”) and further in view of Burke et al. (10,684,591; “Burke”).
Regarding claim 1, El Amili discloses in figure 3, and related figures and text, embodiments of photonic systems, and related methods, that combine 310 two laser beams having different frequencies after being emitted by different lasers 305 and 306. The combined beams impinge upon photodetectors 312 and 318 which produce output beat patterns determined in part by the original frequencies and/or by the sidebands generated by electro-optical modulation 314. El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036] (“the reference oscillator 317 provides a reference clock signal directly to a locking circuit 321”).
El Amili – Figure 3
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Further regarding claim 1, El Amili does not explicitly disclose a vapor cell used by the pump and probe optical signals to perform MTS to generate a beatnote.
However, Osipenko discloses in figure 2, and related figures and text, embodiments of devices, and related frequency offset methods, ‘based on modulation transfer spectroscopy and the use of a broadband electrooptic.’ Osipenko, abstract.
Osipenko- Figure 2
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Consequently, in light of Osipenko’s disclosures of MTS-based frequency offsetting device and method embodiments, it would have been obvious to one of ordinary skill in the art to modify El Amili’s photonic system embodiments to disclose :a first laser source; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; configured to generate a pump optical signal for modulation transfer spectroscopy (MTS); Osipenko, figure 2, and related figures and text; a second laser source; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; configured to generate a probe optical signal for MTS; Osipenko, figure 2, and related figures and text; an optical combiner configured to optically combine a portion of the pump and probe optical signals to generate a combined optical signal; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; a photodiode configured to receive the combined optical signal and output a beatnote; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; a control system configured to, based on receiving the beatnote, Osipenko, figure 2, and related figures and text; adjust a parameter of at least one of the first or second laser sources to set a desired frequency offset between the pump and probe optical signals; Osipenko, figure 2, and related figures and text; and a vapor cell used by the pump and probe optical signals to perform MTS; Osipenko, figure 2, and related figures and text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; because the resulting configurations and related methods would facilitate predictably generating and comparing optical beat notes, frequency offsets, and locked frequencies. Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
Burke – Figure 2
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Burke – Selected Text
abstract (“An optical atomic clock includes a fiber-coupled electro-optic modulator to phase modulate and suppress residual amplitude modulation of a frequency-doubled laser; a rubidium-enriched vapor cell configured to perform a two-photon transition of rubidium atoms to generate a fluorescence signal from the laser; and a differential lock mechanism to stabilize a frequency of the fluorescence signal to a resonance frequency of the two-photon transition of the rubidium atoms.”).
column 2, lines 25-45 (“ In view of the foregoing, an embodiment herein provides an apparatus comprising a laser source to generate a light beam at a predetermined frequency; a frequency comb device to generate an optical beat note from a first portion of the light beam; an optical waveguide to modulate a phase of a second portion of the light beam, wherein the optical waveguide comprises a fiber-coupled electro-optic modulator, and wherein residual amplitude modulation is suppressed in the optical waveguide; an erbium doped fiber amplifier to amplify the frequency of the second portion of the light beam; a vapor cell assembly comprising rubidium atoms, the vapor cell assembly configured to perform a two-photon transition of the rubidium atoms to generate a fluorescence signal from the second portion of the light beam; a controller to lock a frequency of the fluorescence signal to a resonance frequency of the two-photon transition of the rubidium atoms; a frequency counter to count the optical beat note; and a processor to compare the locked frequency of the fluorescence signal to the optical beat note.”).
column 2, line 61 – column 3, line 5 (“an optical atomic clock comprising a fiber-coupled electro-optic modulator to phase modulate and suppress residual amplitude modulation of a frequency-doubled laser; a rubidium-enriched vapor cell configured to perform a two-photon transition of rubidium atoms to generate a fluorescence signal from the laser; and a differential lock mechanism to stabilize a frequency of the fluorescence signal to a resonance frequency of the two-photon transition of the rubidium atoms. The optical atomic clock may comprise a detector to detect a magnitude of the fluorescence signal, and a retro-reflector that is positioned facing the detector.”).
column 5, line 26 – column 8, line 49 (“… an apparatus 10 for providing an atomic frequency standard… he apparatus 10 comprises a laser source 20 to generate a light beam 30 at a predetermined frequency. … The laser source 20 acts as the local oscillator for the frequency standard. The apparatus 10 includes a frequency comb device 40 to generate an optical beat note 31 from a first portion 32 of the light beam 30. …. the repetition rate of the frequency comb device 40 may be photodetected by a detector 36 …The apparatus 10 includes an optical waveguide 50 to modulate a phase (i.e., phase modulation) of a second portion 34 of the light beam 30, wherein the optical waveguide 50 comprises a fiber-coupled electro-optic modulator 60, and wherein residual amplitude modulation is suppressed .….the apparatus 10 includes an erbium doped fiber amplifier 24 … A vapor cell assembly (also referred to herein as “vapor cell”) 80 comprising rubidium atoms 90 is provided …to perform a two-photon transition of the rubidium atoms 90 to generate a fluorescence signal 100 …The apparatus 10 further includes a controller 110 to lock a frequency of the fluorescence signal 100 to a resonance frequency of the two-photon transition of the rubidium atoms 90. … the light beam 30 first enters an optical isolator (ISO) 21, and then enters a splitter 195 …The apparatus 10 may comprise a voltage source …140 to apply a DC offset voltage … to the electro-optic modulator 60. … After the transimpedance amplifier (e.g., pre-amplifier 170), the output signal 47 from the photomultiplier tube 160 is demodulated by the sinusoidal modulation applied to the electro-optic modulator 60 in a phase detector 230, resulting in a laser detuning-dependent error signal 48 for locking the output signal 47 to the atomic resonance….”).
Regarding dependent claims 16 and 17, it would have been obvious to one of ordinary skill in the art to modify El Amili in view of Osipenko and further in view of Burke, as applied in the rejection of claim 1, to disclose:
16. The photonic system of claim 1, wherein the control system is configured to modulate the first laser source in order to generate a modulated pump optical signal for performing MTS. El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
17. The photonic system of claim 1, wherein the control system is further configured to use a spectroscopy signal resulting from passing the pump and probe optical signals through the vapor cell to lock the probe and pump optical signals. El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
because the resulting configurations and related methods would facilitate predictably generating and comparing optical beat notes, frequency offsets and locked frequencies. Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
Regarding independent claim 24, it would have been obvious to one of ordinary skill in the art to modify El Amili in view of Osipenko and further in view of Burke, as applied in the rejection of claims 1, 16, and 17, to disclose: a method, comprising: receiving two laser signals from two separate laser sources; generating a beatnote between the two laser signals using a photodiode; setting a desired frequency offset between the two laser signals based on the beatnote; modulating one of the two laser signals to generate a pump optical signal, wherein the other of the two laser signals is unmodulated to generate a probe optical signal; and transmitting the pump optical signal and the probe optical signal to a vapor cell to perform modulation transfer spectroscopy (MTS); El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text; because the resulting configurations and related methods would facilitate predictably generating and comparing optical beat notes, frequency offsets and locked frequencies. Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
Claims 2-14
Claims 2-14 are rejected under 35 U.S.C. 103 as being unpatentable over El Amili et al. (2022/0190920; “El Amili”) in view of Osipenko et al. (Offset Laser Frequency Stabilization Using Modulation Transfer Spectroscopy. Meas Tech 66, 1–5 (2023); “Osipenko”) and further in view of Burke et al. (10,684,591; “Burke”), as applied in the rejection of claims 1, 16-17, and 24, and further in view of Regarding claims 2-14, as dependent upon claim 1, Churaev disclosures in figures 1-4 and related text, for example, Churaev – Selected Text, heterogeneously integrated photonic platforms comprising non-linear optical circuit configurations mechanically and optically coupled to linear optical circuits configurations. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text (“…heterogeneously integrated LiNbO3 photonic platform employing wafer-scale bonding of thin-film LiNbO3 to silicon nitride (Si3N4) photonic integrated circuits…The platform maintains the low propagation loss … and efficient fiber-to-chip coupling … of the Si3N4 waveguides and provides a link between passive Si3N4 circuits and electro-optic components with adiabatic mode converters…”).
Churaev – Selected Text
abstract (“…heterogeneously integrated LiNbO3 photonic platform employing wafer-scale bonding of thin-film LiNbO3 to silicon nitride (Si3N4) photonic integrated circuits…The platform maintains the low propagation loss … and efficient fiber-to-chip coupling … of the Si3N4 waveguides and provides a link between passive Si3N4 circuits and electro-optic components with adiabatic mode converters…”).
page 1 (“ultra-high-Q optical microresonators, efficient electro-optic frequency comb generation, frequency converters and non-reciprocal devices…In addition, using LiNbO3integrated photonic circuits, electro-optic modulation both at CMOS voltage levels and at high speed (beyond 100 GHz) has been achieved…offering routes toward compact integrated LiNbO3 modulators”).
page 1 (“integrated LiNbO3 photonic integrated circuits (PICs) are also of high interest for nonlinear photonics, for example, for efficient second-harmonic generation, optical squeezing, parametric amplification, and Kerr comb generation”).
page 2 (“As an alternative to conventional bulk LiNbO3 and ridge waveguide- based photonic devices, hybrid platforms combining thin-film LiNbO3 with waveguides made of Si, Si3N4, or Ta2O5 have been recently developed…(see Fig. 1a, b). With proper geometry optimization, the heterogeneously integrated LNOI devices can reach electrooptic performance comparable to that of the all-LNOI platforms32 (VπL=2.3 V⋅ cm for push-pull Mach-Zehnder modulators”).
figure 1 (“Mach-Zehnder interferometer… hybrid optical mode profile for a waveguide with 38% optical mode participation in lithium niobate”).
page 3(“the wafer level integration becomes an attractive and cost effective method for heterogeneous LNOI PICs. Our approach combines the maturity of Si3N4 integrated photonics with the Pockels effect of LiNbO3 and enables hybrid PICs”).
page 3 (“To illustrate the versatility, lithographic precision, complexity, and yield of the hybrid platform, we design a reticle with various devices. Figure 2e shows the design layout of the Si3 N4 photonic integrated circuits for a 100 mm wafer; it contains nine fields with 16 chips each – in total, more than 100 chips with dimensions of 5 mm× 5 mm. The reticle includes chips with different types of devices: (1) microresonators with a free spectral range (FSR) of either 100 GHz or 21 GHz, the former being used for electro-optic comb generation; (2) photonic molecules consisting of a pair of coupled microresonators each with a FSR of 50 GHz, as used for microwave to optical conversion schemes; and (3) waveguides with a length of several centimeters for supercontinuum generation….photonic circuits with straight waveguides and multiple adiabatic transitions between silicon nitride and hybrid optical mode having larger (38–55%) mode participation in lithium niobate due to a different waveguide aspect ratio …we deposit either tungsten or gold electrodes on top of the LiNbO3 adjacent to the waveguides with an electrode-electrode gap of 6 μm. Figure 1h shows the performance of a phase modulator, with a length of 4 mm (device image in Fig. 1g) and a confinement of 38%. Measuring the phase shift with the use of a Mach-Zehnder interferometer,…By reducing the Si3N4waveguide width (and therefore increasing the mode participation in the LiNbO3 layer up to 52%) and decreasing the distance between electrodes down to 5.5 μm, we improve the electro-optic performance…”).
page 3 (“broadband frequency-comb-assisted spectroscopy… of multiple microresonators across the entire wafer with three different external-cavity diode lasers covering the wavelength ranges of 1260–1360nm, 1355–1505 nm, and 1500–1630nm”).
page 3 (“nearly uniform evanescent coupling of optical microresonators”).
page 4(“integrated LiNbO3 devices demonstrated the possibility of using embedded silicon edge-couplers”).
page 5(“The lithographic precision of the Si3N4 photonic circuit layer provides our heterogeneous integration approach with versatility and robustness, as confirmed by the implementation of a W-shaped 3 dB splitter/coupler… (see Fig. 3g) that uses the hybrid Si3N4-LiNbO3 mode but is defined solely by underlying Si3N4 inverse tapers. Splitters are important components for many optical devices, such as electro-optic modulators, optical networks, and lasers based on reflective semiconductor optical amplifiers. The elegance of this type of splitter is in its simplicity of design. Due to the presence of the LiNbO3 slab and the single-mode nature of our hybrid waveguides, the optical mode is adiabatically transferred from the input arm to the output arms. We make the tapered sections 100 μm long, ensuring a small footprint for integrated components exploiting this design. Transmission measurements of the device reveal a flat response, with power asymmetry between the two arms”).
page 6 (“we perform supercontinuum generation in the hybrid Waveguides”).
page 6 (“direct wafer-scale bonding that endows the mature low-loss Si3N4 technology with the second order nonlinearity … of LiNbO3.”).
page 6 (“a heterogeneously integrated LiNbO3 photonic platform combines all the beneficial features of Si3N4 PICs at wafer scale. A comparison of the simultaneously achieved desirable features is given in Supplementary Table 1. The electro-optic performance depends on the optical mode confinement in the LiNbO3 slab layer and can reach levels comparable to that of ridge waveguide structures while keeping propagation losses independent of the quality of the LiNbO3 etching. Possible applications of our platform include photonic switching networks for neuromorphic or quantum computing, devices for quantum state transduction from microwave to optical photons, integrated electro-optic frequency comb sources, on-chip generation of second-harmonic and squeezed light, as well as high-speed electro-optic devices for optical communications…”).
Consequently, it would have been obvious to one of ordinary skill in the art to modify El Amili in view of Osipenko and further in view of Burke, as applied in the rejection of claims 1, 16-17, and 24, to disclose:
2. The photonic system of claim 1, further comprising: a photonic integrated circuit (PIC) configured to receive the pump and probe optical signals, the PIC comprising: the combiner that optically combines a portion of the pump and probe optical signals; and amplitude controls configured to adjust amplitudes of the pump and probe optical signals. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
3. The photonic system of claim 2, further comprising: a phase modulator disposed on the PIC, or disposed on a second PIC that is optically coupled to the PIC, wherein the phase modulator is configured to receive a portion of the pump optical signal and modulate the pump optical signal for performing MTS. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
4. The photonic system of claim 3, wherein the control system is configured to control the phase modulator to generate spectroscopy signals derived from transmitting the pump and probe optical signals through the vapor cell. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
5. The photonic system of claim 3, wherein the phase modulator is disposed on the second PIC, wherein the second PIC is formed from a second order non- linearity material. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
6. The photonic system of claim 5, wherein the second PIC comprises frequency doublers configured to change the frequency of the pump and probe optical signals. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
7. The photonic system of claim 6, wherein the second PIC comprises a Mach-Zehnder interferometer (MZI) structure configured to receive the pump optical signal, wherein a first part of the MZI structure implements a push-pull amplitude modulator to cancel out residual amplitude modulation while a second part of the MZI structure implements one of the amplitude controls. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
8. The photonic system of claim 3, wherein the phase modulator is disposed on the PIC, wherein the PIC includes at least a first layer that is a second order non-linearity material, wherein at least one of the amplitude controls is formed in a second layer of the PIC that does not include the second order non-linearity material. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
9. The photonic system of claim 8, wherein the PIC comprises frequency doublers implemented using the first layer, wherein the frequency doublers are configured to change a frequency of the pump and probe optical signals. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
10. The photonic system of claim 2, wherein the PIC comprises resonator or filter structures to force single longitudinal mode operation and narrow a linewidth of the pump and probe optical signals before reaching the amplitude controls and the photodiode. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
11. The photonic system of claim 2, wherein the PIC is configured to receive a frequency comb and combine the frequency comb with a portion of the probe optical signal. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
12. The photonic system of claim 11, wherein the PIC comprises: a supercontinuum generation waveguide (SGW) configured to spread a spectrum of the frequency comb. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
13. The photonic system of claim 12, further comprising: a second PIC comprising a second order non-linearity material, the second order non-linearity material comprising: a frequency doubler configured to change a frequency of the frequency comb after passing through the SGW. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
14. The photonic system of claim 12, further comprising: a second PIC comprising a second order non-linearity material, wherein the second PIC is aligned with the PIC, wherein the second PIC comprises: a SGW configured to spread a spectrum of the frequency comb; and a frequency doubler formed using the second order non-linearity material, wherein the frequency doubler is configured to change the frequency of the frequency comb after passing through the SGW, wherein the frequency comb first passes through the second PIC before being optically combined with the portion of the probe optical signal in the PIC. Churaev, figures 1-4 and related text, for example, Churaev – Selected Text; El Amili, figure 3, and related figures and text, for example, paragraphs [0029]-[0036]; Osipenko, figure 2, and related figures and text; Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
because the resulting configurations and related methods would facilitate designing, fabricating, and deploying ‘scalable, foundry-ready, complex integrated photonic circuits;’ Churaev, abstract, that facilitate predictably generating and comparing optical beat notes, frequency offsets and locked frequencies. Burke, figure 2, and related figures and text, for example, Burke – Selected Text.
Claim 15
Claim 15, as dependent upon claim 2, is rejected under 35 U.S.C. 103 as being unpatentable over El Amili et al. (2022/0190920; “El Amili”) in view of Osipenko et al. (Offset Laser Frequency Stabilization Using Modulation Transfer Spectroscopy. Meas Tech 66, 1–5 (2023); “Osipenko”) and further in view of Burke et al. (10,684,591; “Burke”), as applied in the rejection of claims 1, 16-17, and 24, and further in view of Churaev et al. (A heterogeneously integrated lithium niobate-on-silicon nitride photonic platform, in Conference on Lasers and Electro-Optics/Europe (CLEO/Europe 2023) and European Quantum Electronics Conference (EQEC 2023), Technical Digest Series (Optica Publishing Group, 2023), paper ce_9_1.; “Churaev”), as applied in the rejection of claims 2-14, and further in view of Padmaraju et al. (10,742,324; “Padmaraju”).
Regarding claim 15, Padmaraju discloses in figure 1, and related figures and text, Mach-Zehnder modulators 20 having one arm with a ‘heater-based bias tuner’ 27. Padmaraju discloses in figure 1, and related figures and text, for example, column 10, lines 21-46 (“ Advantageously, adjusting the DC bias settings of the inner MZMs 20 so as to minimize the dither frequencies f.sub.1, f.sub.2 in the optical power at the output of QM 10 leads to the bias offsets 77 of the inner MZMs 20 that minimize the carrier pass-through in the output optical signal 103 of the QM 10, which corresponds to eliminating or at least reducing the IQ offset 85. However, we found that in a QM with a single-push bias control, such as QM 10 of FIG. 1, this type of bias control may simultaneously cause the appearance of a quadrature error in the output signal constellation, which is illustrated in FIG. 3C. The terms “single-push bias”, “single-push bias dither”, and their derivatives refer to a type of bias control when an MZM bias is adjusted or dithered by affecting only, or predominantly, one arm of an MZM or an MZI. Single-push bias and single-push bias dither is typically used for silicon-based or generally semiconductor-based integrated IQ modulators such as QM 10 illustrated in FIG. 1, in which linear electro-optic effect may be absent or too weak to adjust the optical phase as needed, and in particular when heater-based bias tuners are used to vary the refractive index in one of the MZM arms. In such embodiments, bias control methods that are based on minimizing the presence of a signature of an MZM bias dither in an output signal of the QM may result in a quadrature error in the output optical signal of the QM that correlates with the ER of the inner MZMs.) and column 11, lines 32-44 (“Typically, semiconductor-based integrated IQ modulators, such as the QM 10, use resistive heaters as bias tuners 27 and 47, and usually in only one of the arms of each inner MZM. The phase shift induced in a waveguide arm by such bias tuner is proportional to the amount of heat generated by the resistive heater, and is uni-directional as a function of bias voltage Vb applied thereto, i.e. it always changes in the same direction as the absolute value of the voltage applied across the resistive heater increases, regardless of the sign of the voltage across the resister heater. The bias control using such uni-directional single-push bias tuners is associated with a significant correlation between the ER of the inner MZMs and the QE at the output of the IQ modulator.”).
Padmaraju -Figure 1
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Consequently, it would have been obvious to one of ordinary skill in the art to modify El Amili in view of Osipenko and further in view of Burke, as applied in the rejection of claims 1, 16-17, and 24, and further in view of Churaev, as applied in the rejection of claims 2-14, such that the amplitude controls comprise Mach-Zehnder interferometers (MZI) comprising thermo-optic heaters as phase shifters in one arm; Padmaraju, because the resultant configuration would facilitate controlling effects related to phase shifts. Padmaraju column 10, lines 21-46.
Conclusion
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/PETER RADKOWSKI/Primary Examiner, Art Unit 2874
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