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Borate Crystalline Materials for Lasers

#B-1616


Novel Er,Yb-co-Doped Borate Crystalline Materials and 1.5-1.6 micrometers Highly Efficient Bulk and Waveguide Lasers for Range-Finding, Medicine and Telecoms

Tech Area / Field

  • PHY-OPL/Optics and Lasers/Physics

Status
3 Approved without Funding

Registration date
11.03.2008

Leading Institute
Belorussian National Technical University, Belarus, Minsk

Supporting institutes

  • Moscow State University, Russia, Moscow

Collaborators

  • St Andrews University / School of Physics and Astronomy, UK, St Andrews\nUniversity of Dundee / Faculty of Engineering and Physical Sciences, UK, Dundee

Project summary

The project's objective is to develop growth technology of bulk crystal and thin crystalline layers of YAl3(BO3)4 (YAB) and other crystals of borate family co-doped with Er3+ and Yb3+ and to demonstrate efficient CW, Q-switched and ultrafast diode-pumped solid-state and waveguide lasers based on these materials emitting in the 1.5-1.6 μm spectral range for applications in medicine and telecommunications.

The state of the art. Er,Yb-co-doped glasess are well known as acceptable laser materials for the 1.5 μm spectral region. However, the main drawback of glasses as laser host materials in comparison with crystals is their relatively low thermal conductivity which limits the output power at the level of about 150-200mW. The search for an efficient crystalline host was found to be a relatively complex problem. The most efficient 1.5 μm lasing in Er-doped crystals was reported in borates (Yb,Er:YCOB) where output power of about 250 mW and slope efficiency up to 26.8% were demonstrated under diode-laser pumping. Recently, Er,Yb:YAB was reported by project proposal authors as a very promising laser material with potential of multi-Watt generation under diode-laser pumping at about 980 nm. Disadvantage of YAB as a host laser material is that the crystal growth is difficult.

As a result of the project fulfillment new Yb, Er borate materials for telecom application in the spectral range of 1.53 – 1.6 μm with high bit rates will be created.

The impact of the proposed project on the progress in this field.

The project would allow to elaborate technology of crystal growth of new extremely efficient Er,Yb-crystalline laser material(s) and to built-up new efficient diode-pumped lasers emitting in the eye-safe region near 1.5 μm. As a result of the successful project implementation break-through in the field of crystalline eye-safe Q-switched and mode-locked lasers could be achieved.

Competence of the project team in the specified area.

The team from BNTU is specialized in the development of new laser materials and saturable absorbers for diode-pumped solid-state lasers including ultrafast lasers. One of the main research activities of this Group is investigation of the spectroscopic properties and laser performance of rare-earth-doped crystals. A number of efficient laser materials including well-known Yb:KYW and Yb:KGW laser crystals and a number of materials for passive Q-switches were invented in this Group.

Group from MSU is material-growth-oriented team with great experience in the growth of different oxide crystals, including crystals of borate family.

Expected results and their application.

  • Growth technology for bulk crystals and thin layers of YAB and other borates co-doped with Er and Yb will be elaborated.
  • Er,Yb:YAB crystals and crystalline layers of laser quality will be grown.
  • Spectroscopic characteristics of Er,Yb:YAB and other borate materials as laser materials will be investigated.
  • Efficient diode-pumped CW, Q-switched and ultrafast Er-lasers of watt level as well as waveguide lasers emitting in the spectral range of 1.5-1.6 μm will be demonstrated.

The project will result in the development of new laser materials and new generation of eye-safe Er-lasers with world record parameters. This will promote production of commercial lasers in the 1.5-1.6 μm spectra range for applications in medicine and telecoms.

Meetings ISTC Goals and Objectives

The project meets the ISTC goals and objectives.

  • The project execution will provide weapon project participants an opportunity to redirect their talents to peaceful activities.
  • Integration of project participants into the international optical community, especially in European scientific community, will be strengthened due to collaboration with leading European group in ultrafast lasers.
  • Applied research and technology development for peaceful purposes in the field of solid-state lasers will be supported.
  • The project will contribute to the solution of international technical problem: development of femtosecond system with repetition rate of tens GHz level.
  • The transition to market-based economy responsive to civil needs will be reinforced since the results open new opportunities for companies in area of photonics to arrange mass commercial production of advanced lasers for public applications.

Scope of activities

The project will be executed during 3 years by 12 scientists and engineers from participating institutions.

The Project activities are pided into four Tasks:


Task 1. Improvement of crystal growth technology of Er,Yb:YAB and other borates (MSU).
Task 2. Investigation of laser related spectroscopic properties of Er,Yb-doped YAB and other borates (BNTU).
Task 3. CW, Q-switched and mode-locked laser experiments (BNTU).
Task 4. Preparation and characterization of Er,Yb:YAB crystalline thin layers for waveguide lasers (MSU, BNTU).

The total Tasks efforts are 5,747 person*days. The main goal of the MSU group consist in improvement of growth technology of borates crystals co-doped with Yb and Er ions and obtaining of crystals and crystalline layers of high optical quality. The goal of the BNTU group mainly consist in investigation of spectroscopic characteristics of single crystals, crystalline layers and waveguides obtained as well as in carrying out laser experiments: cw, Q-switch and mode locking regimes realization.

Role of foreign collaborator

The project represents an international high-technology collaborative effort. Joint laser experiments with sub-picosecond pulse generation from Er,Yb:YAB lasers will be performed together with the group of Prof. W. Sibbett, UK, the collaborator of the project.

  • Information exchange with the collaborator in the course of project implementation;
  • The collaborator will provide comments to the annual technical reports submitted by project participants to the ISTC;
  • The collaborator will share use of laser equipment for joint investigations;
  • The collaborator will make cross-checks of results obtained in the course of project implementation.

Technical approach and methodology

Er,Yb-doped YAB crystals will be grown by flux technique. Characterization of crystals will be performed by using conventional optical and spectroscopic equipment as well as by means of experimental set ups made be the project participants. Saturable absorber and Kerr-lens mode-locking (KLM) techniques will be used for ultrafast laser demonstration. Thin crystalline layers of Er,Yb:YAB on undoped YAB substrates will be prepared by liquid phase epitaxy (LPE) techniques.


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