OptiGrate QCBG-795/780 Chirped Volume Bragg Grating for Quantum Optical Control

Overview

The OptiGrate QCBG-795/780 Chirped Volume Bragg Grating is a monolithic, passive optical dispersion element engineered for precision spectral phase control in quantum optical systems. Fabricated in photosensitive PTR (photo-thermo-refractive) glass, the device implements a spatially non-uniform refractive index modulation along the optical propagation axis—creating a linear or higher-order chirp in the Bragg wavelength condition. This architecture enables deterministic group delay dispersion (GDD) compensation or programmable pulse shaping without moving parts. Unlike surface-relief gratings or prism-based compressors, the QCBG operates in transmission geometry with near-zero wavefront distortion, minimal insertion loss, and intrinsic thermal and mechanical stability. Its design adheres to the coupled-mode theory of volume holography, ensuring high fidelity in both amplitude and phase transfer functions—critical for coherent Raman driving of hyperfine qubits, ultrafast laser pulse compression, and narrowband spectral filtering in atomic physics experiments.

Key Features

• High diffraction efficiency (>90%) across operational bandwidths at 780 nm and 795 nm—optimized for alkali atom transitions (e.g., Rb D1/D2 lines)
• Large, controllable dispersion: ~400 ps² per single pass; up to ~800 ps² in double-pass configuration—enabling sub-100-fs pulse manipulation
• Narrow spectral bandwidth: 0.1 ± 0.03 nm (FWHM), corresponding to ~12.5 GHz at 795 nm—suitable for quantum memory interface and cavity-enhanced spectroscopy
• Wavelength tunability via precise angular alignment or thermally induced index shift—supporting active feedback stabilization in locked laser systems
• Robust PTR glass substrate with low photoinduced drift, high laser-induced damage threshold (LIDT > 5 J/cm² for 10 ns pulses at 795 nm), and long-term environmental stability
• Compact footprint: 11.25 mm × 6.25 mm × thickness (standard 5–10 mm)—designed for integration into vacuum-compatible quantum optics breadboards and fiber-coupled modules

Sample Compatibility & Compliance

The QCBG-795/780 is compatible with free-space collimated beams (typical input beam diameter: 1–5 mm) and can be integrated into fiber-pigtailed packages upon request. It meets standard requirements for quantum laboratory instrumentation under ISO/IEC 17025-accredited calibration workflows. While not a regulated medical or industrial safety device, its optical performance conforms to ANSI Z136.1 (Safe Use of Lasers) and IEC 60825-1 classifications when used within specified power and pulse parameter limits. The device supports traceable characterization per NIST-traceable spectrophotometric and interferometric methods, including spectral response mapping and GDD verification using white-light interferometry or frequency-resolved optical gating (FROG).

Software & Data Management

As a passive optical component, the QCBG requires no embedded firmware or driver software. However, system-level integration benefits from compatibility with common lab automation platforms: LabVIEW™ (via DAQ-controlled rotation stages or temperature controllers), Python-based control suites (e.g., PyVISA + Arduino/MCP9808 for thermal tuning), and MATLAB® toolboxes for dispersion modeling (e.g., using transfer matrix method simulations). Full spectral and dispersion datasets—including measured reflectivity/transmission spectra, angular tuning curves, and GDD vs. wavelength—are supplied in ASCII (.txt) and HDF5 formats for reproducible analysis. All characterization reports include uncertainty budgets aligned with EURAMET cg-18 guidelines for optical metrology.

Applications

• Coherent Raman driving of hyperfine qubits in trapped-ion and neutral-atom quantum processors—leveraging phase-to-amplitude conversion for high-fidelity π-pulse generation
• Pulse compression and stretching in Ti:sapphire and fiber-based ultrafast oscillators/amplifiers operating near 780–795 nm
• Narrowband spectral filtering for atomic vapor cell magnetometers, optical clocks, and Doppler-free saturated absorption spectroscopy
• Dispersion management in multi-pass cavity designs for cavity-enhanced spontaneous parametric down-conversion (SPDC)
• Stabilization reference elements in external-cavity diode lasers (ECDLs) targeting Rb-87 (780.24 nm) and Rb-85 (794.98 nm) transitions
• Hybrid filter modules combining QCBG with fiber-Bragg-grating (FBG) arrays for GHz-scale channel selection in quantum networking testbeds

FAQ

What is the maximum average power the QCBG-795 can handle in continuous-wave operation?

The device supports average powers up to 5 W (free-space, TEM₀₀, M² < 1.1) with appropriate beam homogenization and thermal anchoring. For higher powers, custom mounting solutions with copper heat-sinking are available.
Can the QCBG be used in reflection mode?

No—it is designed exclusively for transmission geometry. Reflection-mode operation would violate the phase-matching condition due to asymmetry in the chirped index profile.
Is angular alignment sensitivity quantified in the datasheet?

Yes: angular tuning coefficient is typically −0.018 nm/mrad at 795 nm; full-width half-maximum angular acceptance is ±0.8 mrad for >90% diffraction efficiency.
Do you provide calibration certificates with NIST-traceable measurements?

Yes—each unit ships with a certificate of conformance including spectral transmission/reflectivity scans, GDD maps, and LIDT test records, all traceable to NIST SRM 2036 and calibrated reference spectrometers.
Are custom center wavelengths outside 780/795 nm supported?

Yes—custom designs are available from 400 nm to 1100 nm; lead time and minimum order quantities apply based on PTR glass photosensitivity and exposure setup constraints.