RTP, Rubidium Titanyl Phosphate

RTP, Rubidium Titanyl Phosphate

Keywords: RTP, Rubidium Titanyl Phosphate, NLO, nonlinear optics
Nov 12, 2020 View: 1722 Data Sheet

RTP which has only recently become commercially available is the material of choice for many NLO and electro-optic applications. Its high optical damage threshold makes it especially useful in high power SHG and OPO applications. RTPs high electrical

SRC Series Rubidium Titanyl Phosphate (RTP) Crystals

RTP crystal belongs to KTP crystal family. The outstanding electro-optical properties of RTP together with high damage threshold made it possible to use for high-power laser applications in many areas: medical, industrial, defense, etc.

RTP material is widely recognized for these features:

  • Reliable homogeneity
  • High laser damage threshold
  • Non-hygroscopic
  • Low absorption losses
  • No acoustic ringing
  • Stability over a wide temperature range (-50ºC – +70ºC)

RTP, which has only recently become commercially available, is the material of choice for many NLO and electro-optic applications. Its high optical damage threshold makes it especially useful in high power SHG and OPO applications. RTP’s high electrical resistivity is important for many electro-optic applications, and in the production of Periodically Poled RTP elements.

RTP vs. KTP Comparison Chart

Property (Type II SHG at 1064nm) KTP RTP
Phase matchable range (nm) 980-1080 1050-1140
Nonlinear coefficients (pm/V)
d33 16.9 17.1
d31 2.5 3.3
d32 4.4 4.1
deff 3.34 2.45
Phase matching angle (deg) 22-25 58
Walk-off angle (deg) 0.26 0.4
Angular acceptance (mrad cm) 20 20
Temperature acceptance (°C cm) 25 40
Transparency range (nm) 350-4500 350-4500
Other Properties
Wavelength of noncritical OPO 1064nm (nm) 1570/3300 1600/3200
Electro optical coefficients (pm/V)
r33 36.3 39.6
r13 9.5 12.5
r23 15.7 17.1
Dielectric constant εeff 13 13
Optical damage ratio (to KTP) 1 1.8
Electrical conductivity along Z axis (Ω-1 cm-1) 10-6-10-7 10-11-10-12
Pyroelectric coefficient (C/cm2 K) 7 x 10-9 4 x 10-9

1. SRC Series Slab RTP EO Cells

Slab EO cell is made of RTP crystals and offers superior properties for users in the aerospace, defense, medical, industrial, civil and scientific applications. Slab RTP EO cells are assembled in a compact and flat thermally compensated double-crystal configuration. It may be used for slab cavity or multi-channels modulations. Due to the unique design, higher average power density can be allowed, as well as elliptical beam or two round beams.

Application:

  • Q switches
  • Pulse pickers
  • Phase modulators
  • Amplitude modulators
  • Cavity dumpers
  • Shutters
  • Attenuators & deflectors

Advantages:

  • Smaller Q switch, flat design
  • Lower HWV (L/d factor)
  • Possibility to spread power density for high power lasers using slab form beams (reduce power density by enlarge beam spot in one direction) or using beam splitter
  • Faster rise time and no piezoelectric effect
  • Possibility to achieve higher extinction ratio in EO cells due to compensation of refractive indexes gradient
  • May operate at higher power density due to less sensitivity to induced thermo- effect due to parallel orientation of axis in both crystals (thermo- conductivity in Z direction is 1.5 times higher than in X or Y directions)

Typical Specifications:

Operational range 500-3000nm
Transmission @1064nm >99%
Half Wave voltage 1.5kV (for SLAB EO CELL size: 8x4x10)
Extinction ratio Up to 30dB
Clear aperture 1.5*1.5 mm to 15*15 mm
Crystal length Up to 50 mm
Acceptance angle < 4deg
Standard AR coating @1064nm R < 0.1%
Damage threshold Up to 1 GW/cm2, at 1064 nm, 10 ns pulse

2. SRC Series RTP EO Devices

RTP (Rubidium Titanyl Phosphate) is a robust electro‐optic crystal suitable for a wide variety of applications (such as Q‐Switches, Amplitude & Phase Modulators, Pulse Pickers, etc.) and operation in industrial, medical, and defense products. The crystal is transparent at most common visible and near infrared laser wavelengths. It performs well over a wide temperature range (from ‐50◦C to +70◦C) and at high repetition rates. RTP based Q‐switch devices are offered in matched pair configurations, in a temperature compensating design. When used for applications such as Q‐Switches and Amplitude Modulators, the crystals are mounted in a way that the input beam is polarized along the diagonal of the face.

Features:

  • Low half-wave voltage
  • High damage threshold
  • Non hygroscopic
  • Minimal ringing at high rep rates
  • Operates over wide temperature range

Single Crystals Tolerances

Length per crystal (L) ± 0.5 mm
Height (H) / Width (W) ± 0.10 mm
Perpendicularity < 20 arc min
Parallelism < 10 arc sec
Scratch/dig 10/5 in the clear aperture
Chamfers < 0.2 mm x 45°± 5°
Electrodes Ti on Z-sides
Marking polarity of Z-axis (+) on the side surface
AR/AR coatings : R<0.1%
Damage threshold >600 MW/cm2 @1064 nm, 10ns, 10Hz
Side surfaces fine ground < 30μm

Matched Pair

Lengths matched to within ± 0.002 mm.

Extinction ratio: transmission ratio of matched pair between parallel/crossed polarizers measured at operating wavelength.

Crystals in V-groove with 90° between Z- axes (+) and (-) on the top. Light polarization vertical or horizontal.

Angular adjustment tolerance: 1.5 degree Transmission: > 98.5%

EO-Cell

Wire type: ET1828, Connectronics Corp. Wires length: 150 mm

Connectronics Corp. Total Capacitance: 2.0-3.0 pF (crystal lengths 5 mm)

and 4.0-6.0 pF (crystal lengths 10 mm)

Static Half Wave Voltage at wavelength (λ, nm) according to the following formulas:

X-cut: Vx = (W/2L) x [(9.35 x λ) - 2000] [V] ± 15%

Y-cut: Vy = (W/2L) x [(8 x λ) - 1900] [V] ± 15%

3. SRC Series RTP FOR ELECTRO-OPTICS (EO)

RTP (Rubidium Titanyl Phosphate) is a robust crystal material suitable for a wide range of electro-optics applications. The Electro-Optics cells (Pockels Cells) are based on two RTP elements in a temperature compensating design that enables the use of these devices within a wide temperature range from -60 °C up to +70 °C.

RTP EO Cell Applications:

  • Q-switch
  • Phrase modulator
  • Amplitude modulator
  • Pulse picker
  • Cavity dumper
  • Shutter
  • Attenuator
  • Deflector

Advantages:

  • Low half-wave voltage for EO Cells to enable a compact design
  • Rise time, fall time, and pulse width of 1 ns to enable fast operation
  • Designed to operate over wide temperature range (-50°C to 70°C)
  • High laser-induced damage threshold (up to1000 MW/cm2, at 1064 nm, 10 ns pulse)
  • Minimal ringing, compatible for 1 MHz repetition rate
  • Non-hygroscopic, easy handling, no cover needed
  • The best material in the spectral range of 500-3000 nm for electro-optics applications
  • Very low absorption losses at 1064 nm wavelength
  • Extremely high homogeneity: up to 15*15 mm EO cells as a standard size

RTP EO Cell Structure

RTP EO Cell Product Offerings

  • Thermally compensated matched pair of RTP Elements
  • Single RTP Element (used for phase modulators)
  • Plug in 2 crystals, Electro-optical cells assembly (with / without housing)

Typical Specifications

Operational Range 500-3000 nm
Transmission @ 1064 nm > 99%
Half wave voltage 3.6 kV (for EO Cell size: 9*9*10 mm*2)
Extinction ratio Up to 30 dB
Clear aperture 1.5*1.5 mm to 15*15 mm
Crystal length Up to 50 mm
Acceptance angle < 4 deg.
Standard AR coating @ 1064 nm R < 0.1%
Damage threshold Up to 1 GW/cm2, at 1064 nm, 10 ns pulse

4. SRC Series IRTP Pockels Cell

RTP (Rubidium Titanyl Phosphate) is a robust electro‐optic crystal suitable for a wide variety of applications (such as Q‐Switches, Amplitude & Phase Modulators, Pulse Pickers, etc.) and operation in industrial, medical, and defence products. The crystal is transparent at most common visible and near infrared laser wavelengths. It performs well over a wide temperature range (from ‐500C to +700C) and at high repetition rates. RTP based Q‐switch devices are offered in matched pair configurations, in a temperature compensating design. When used for applications such as Q-switches and Amplitude Modulators, the crystals are mounted such that the input beam is polarized along the diagonal of the face. Our Q-switch is built using 2 RTP (Rubidium Titanyl Phosphate) elements in a temperature compensating design. The unique properties of RTP, including high electrical resistivity (~1012 Ω-cm) and a high damage threshold, result in a Q-switch with excellent properties.

Our new SRC Series IRTP Pockels Cell is the first product that brings the advantages of RTP to the EO mass market. This IRTP is a modified version of our RTP, designed specifically for industrial laser applications. It is ideal for applications that require advanced characteristics, such as non-hygroscopic, high thermal stability, and high repetition rates. This IRTP is a standard off -the- shelf solution that offers high performance EO cells at the price of standard industry Pockels Cell.

Advantages:

  • High Damage Threshold: No: Piezoelectric Ringing
  • Low Insertion Loss: Thermal: Compensating Design
  • Non-hygroscopic

Features:

  • High laser damage threshold
  • Fast rise-fall time and pulse width
  • Non-hygroscopic material
  • Low absorption losses
  • No acoustic ringing (up to at least 350kHz)
  • Thermal stability over a wide operational temperature range (10ºC –50ºC)

SRC Series IRTP Pockels Cell Specifications

IRTP Parameters SRC-IRTP-6 SRC-IRTP-8 SRC-IRTP-10
Aperture 6x6mm 8x8mm 10x10mm
Capacitance <6pf
Quarter wave voltage (@1064) 3.3KV
Optical transmission >99%
ER (@1064) ≥27dB
Damage threshold Typically, >1GW/ cm2
Alignment access 1 axis alignment
Housing Dimensions Round: θ35mm, length 35mm (there is a 1’’ design) Square: 35mmx35mmx35mm
Rise time <1ns
Thermal Stability 10-50 Deg

RTP Q-switch working at 30kHz

BBO Q-switch working at 30kHz

The graphs above show the behaviour of RTP and BBO Q switches at high repetition rates. In particular, the BBO shows Piezoelectric ringing at 30 kHz, while the RTP Q switch shows no ringing at this frequency. The BBO Q switch has a 2.5x2.5x25 mm element, while the RTP Q switch has two 6x6x7mm elements.

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