Characteristics and Applications Of Optical Glass Material Systems​

Optical glass, as a core foundational material in modern optoelectronic technology, directly impacts the resolution, transmittance, and stability of optical systems. With the evolution of optoelectronic technology toward high precision, broad spectral bands, and extreme environments, the material system of optical glass has expanded from traditional crown/flint glasses to various novel functional glasses. This paper systematically reviews the classification system of optical glasses, focusing on analyzing the physical properties and engineering application boundaries of representative materials.

I. Traditional Optical Glass Systems

1. Crown Glass

Typical Representatives: BK7 (Schott K5), K9 (Chinese Grade)
Core Characteristics:

· Low dispersion (Abbe number ν_d = 64–70)

· Moderate refractive index (n_d = 1.51–1.54)

· Exceptional chemical stability (resistant to acid/base corrosion)
Application Boundaries:

· Astronomical telescope objectives (e.g., Hubble Space Telescope primary mirror uses Schott B270)

· Laser resonator cavities (CO₂ laser windows)

· Low-magnification components in microscope objectives

2. Flint Glass

Typical Representatives: F2 (LaK3), BaF10 (Barium-Containing Flint)
Core Characteristics:

· High refractive index (n_d = 1.60–1.80)

· Abnormal dispersion (Abbe number ν_d = 30–50)

· Strong hygroscopicity (requires anti-reflective coating protection)
Application Restrictions:

· High-magnification microscope objectives (compensates spherical aberration)

· Projector lens groups (utilizes high refractive index to shorten optical path)

· Prohibited Scenarios: Humid environments (prone to hydrolytic degradation)

II. Novel Functional Optical Glasses

1. Lanthanum-Calibrated Glass

Typical Representatives: N-LAK34 (Schott), S-LAL12 (Ohara)
Breakthrough Metrics:

· Refractive index temperature coefficient: dn/dT ≤ ±1 × 10⁻⁶ /°C

· Coefficient of thermal expansion (CTE): α = 50–70 × 10⁻⁷ /°C

· Transmission extended to near-infrared (λ = 400–1100 nm)
Engineering Applications:

· Space optical systems (satellite cameras with thermal shock resistance)

· Ultra-precision laser interferometers (zero-expansion lenses)

· High-energy laser reflectors (thermal distortion control)

2. Fluorophosphate Glass (FP Glass)

Typical Composition: Zn(PO₃)₃–AlF₃–LiF System
Performance Advantages:

· Ultra-broadband transmission (250–7000 nm)

· Nonlinear refractive index: n₂ = 2.5 × 10⁻¹⁸ m²/W

· Laser damage threshold > 10 GW/cm²
Application Domains:

· Femtosecond laser micromachining lens groups

· Mid-infrared spectrometers (3–5 μm band)

· High-power laser amplifiers (thermal shock resistance)

3. Chalcogenide Glass (Chalcohalide Glass)

Typical Formulation: Ge–As–S–I System
Unique Properties:

· Infrared cutoff wavelength > 12 μm

· Glass transition temperature (Tg) = 25–45°C (enables moldable shaping)

· Tunable refractive index range: 1.8–2.8
Application Scenarios:

· Thermal imager lenses (8–12 μm band)

· Fiber-optic communication repeaters (mid-infrared window)

· Aspheric mold forming (low-temperature processing advantage)

III. Specialty Functional Optical Glasses

1. Ultraviolet-Grade Fused Silica (UVFS)

Critical Parameters:

· UV transmittance > 90% (λ > 200 nm)

· Hydroxyl content < 1 ppm (eliminates 240 nm absorption peak)

· Radiation hardness > 10⁸ rad (SiO₂ equivalent)
Application Examples:

· Synchrotron radiation beamlines (0.1–100 nm band)

· Deep ultraviolet lithography objectives (193 nm ArF excimer laser)

· Space solar observation mirrors (proton irradiation resistance)

2. Neodymium-Doped Laser Glass

Typical System: Phosphate-Based Nd:LG-790
Laser Characteristics:

· Stimulated emission cross-section: σ = 2.8 × 10⁻²⁰ cm²

· Fluorescence lifetime: τ = 580 μs

· Gain bandwidth: Δλ = 25 nm (tunable output)
Engineering Applications:

· Inertial confinement fusion drivers (megajoule-class amplification modules)

· Eye-safe lidar systems (1.06 μm band)

· All-solid-state femtosecond lasers (chirped pulse amplification)

IV. Material Selection Strategies and Development Trends

1. Engineering Matching Principles

Application Scenario	Prioritized Criteria	Recommended Material
Deep-sea detection systems	Pressure resistance (>10 MPa)/corrosion resistance	Chalcogenide glass + tempered treatment
EUV lithography	Surface roughness (<0.1 nm RMS)	Fused silica/atomic layer deposition coating
Spaceborne remote sensing	Thermal stability (CTE <5 × 10⁻⁷/°C)	N-LASF35 lanthanum glass

2. Technological Evolution Pathways

· Nanocomposite Technology: Doping with Ag/Au nanoparticles enhances nonlinear response (third-order nonlinearity increased by three orders of magnitude).

· Gradient Index Design: Ion exchange fabrication of GRIN lenses improves aberration correction by 40%.

· Eco-Manufacturing Processes: Development of arsenic/heavy-metal-free formulations (EU RoHS compliance rate >95%).

Conclusion
Innovations in optical glass materials are driving optoelectronic systems toward extreme environment adaptability, multi-band synergy, and ultra-high power endurance. Future R&D efforts must focus on integrating material genomic engineering with service environment coupling mechanisms, achieving closed-loop optimization across composition design, fabrication processes, and characterization evaluation to realize dual breakthroughs in optical performance and engineering reliability.