Optical solitons due to quadratic nonlinearities: from basic physics to futuristic applications

This review takes a look at the historical development of the dielectric planar waveguide laser leading to key state-of-the-art technologies that fall within this broad subject area. Discussed herein are many of the advantages offered by the waveguide geometry such as high optical gain, and thus, low threshold-power requirements, suitability for quasi-three-level laser transitions, integration with functional devices on single substrates, guided spatial-mode control, and its considerable immunity to thermal effects and external environmental conditions. A detailed snapshot is made of many active host media for which there has been reported laser action in the planar waveguide geometry, covering many of the major rare-earth-ion transitions. Several fabrication techniques are highlighted and appraised for their applicability to different host media, touching on their benefits and drawbacks. Challenges and future prospects for these lasers are considered.

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Dielectric Solid-State Planar Waveguide Lasers: A Review

This paper reviews the latest developments of diode-pumped Ti,Er:LiNbO/sub 3/ waveguide lasers emitting at wavelengths around 1.5 /spl mu/m. In particular, harmonically mode-locked lasers, Q-switched lasers, distributed Bragg reflector (DBR)-lasers, and self-frequency doubling lasers are discussed in detail. Supermode stabilized mode-locked lasers have been realized using a coupled cavity concept; a side mode suppression ratio of 55 dB has been achieved at 10-GHz pulse repetition rate with almost transform limited pulses. Q-switched lasers with a high extinction ratio (>25 dB) intracavity electrooptic switch emitted pulses with a peak power level up to 2.5 kW and a pulsewidth down to 2.1 ns at 1-kHz repetition frequency. Numerical simulations for both lasers are in a good, almost quantitative agreement with experimental results. A DBR-laser of narrow linewidth (/spl ap/3 GHz) with a permanent (fixed) photorefractive grating and 5 mW output power has been realized. Self frequency doubling lasers have been fabricated with a periodic microdomain structure inside an Er-doped laser cavity; simultaneous emission at the fundamental wavelength, 1531 nm, and at the second harmonic wavelength, 765 nm, has been obtained.

Advanced Ti:Er:LiNbO/sub 3/ waveguide lasers

Optically pumped planar waveguide lasers: Part II: Gain media, laser systems, and applications

The state-of-the-art of Er-doped integrated optical devices in LiNbO/sub 3/ is reviewed starting with a brief discussion of the technology of Er-indiffusion. This technique yields high-quality waveguides and allows a selective surface doping necessary to develop optical circuits of higher complexity. Doped waveguides have been used as single- and double-pass optical amplifiers for the wavelength range 1530 nm</spl lambda/<1610 nm. If incorporated in conventional, lossy devices loss-compensating or even amplifying devices can be fabricated. Examples are an electrooptically scanned Ti:Er:LiNbO/sub 3/ waveguide resonator used as an optical spectrum analyzer and an acoustooptically tunable filter used as a tunable narrowband amplifier. Different types of Ti:Er:LiNbO/sub 3/ waveguide lasers are presented. Among them are free running Fabry-Perot lasers for six different wavelengths with a continuous-wave (CW)-output power up to 63 mW. Tunable lasers could be demonstrated by the intracavity integration of an acoustooptical amplifying wavelength filter yielding a tuning range up to 31 nm. With intracavity electrooptic phase modulation modelocked laser operation has been obtained with pulse repetition frequencies up to 10 GHz; pulses of only a few ps width could be generated. With intracavity amplitude modulation Q-switched laser operation has been achieved leading to the emission of pulses of up to 2.4 W peak power (0.18 /spl mu/J) at 2 kHz repetition frequency. Distributed Bragg reflector (DBR) lasers of emission linewidth /spl les/8 kHz have been developed using a dry-etched surface grating as one of the mirrors of the laser resonator. Finally, as an example for a monolithic integration of lasers and extracavity devices on the same substrate, a DBR-laser/modulator combination is presented.

Er-doped integrated optical devices in LiNbO/sub 3/

The first integrated optical DBR waveguide laser with dry-etched Bragg grating (345 nm period) is demonstrated in Er-diffusion-doped doped zeta -cut LiNbO/sub 3/ with Ti-diffused waveguide. Three different resonator configurations have been investigated. The best device has a threshold of 40 mW coupled pump power ( lambda /sub p/=1484 nm) and emits up to 2 mW CW output power at lambda /sub s/=1531 nm with a typical bandwidth of 3.6 GHz.

DBR waveguide laser in erbium-diffusion-doped LiNbO3

For the first timer a DBR laser has been integrated with a Mach Zehnder intensity modulator in Er diffusion doped, Z cut LiNbO/sub 3/, with Ti indiffused waveguides and dry etched Bragg gratings. The monolithically integrated device has a threshold of 54.8 mW incident pump power (/spl lambda/p=1480 nm) and emits, in a single longitudinal model up to 0.65 mW CW output power at /spl lambda/s=1561 nm. The Mach-Zehnder type intensity modulator has an optical bandwidth >3 GHz.

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Monolithically integrated dbr waveguide laser and intensity modulator in erbium doped linbo3

Lasers with eibium-doped Ti:LiNbO3 waveguides have been reported with dielectric endface mirrors only [1]. This paper reports the first distributed Bragg reflector (DBR) waveguide lasers in erbium-diffusion-doped LiNbO3, an important step towards complex integrated optical circuits in LiNbO3.

DBR STRIPE WAVEGUIDE LASERS IN ERBIUM-DIFFUSION-DOPED LiNbO3

Summary form only given. Reports on the first, to our knowledge, single-mode Er:LiNbO/sub 3/ DBR waveguide laser, monolithically integrated with a Mach-Zehnder-type intensity modulator. This transmitter prototype is an attractive device for high-speed analog transmission and sensor applications. The measured serial resistance of the 6 mm long travelling wave electrode is 10 /spl Omega/ and the calculated RF impedance is 27 /spl Omega/. The frequency response with electro-optical modulation is shown. The integrated laser/modulator device shows a bandwidth of 3.057 GHz at -6 dBe.

H. Schutz

Papers

DBR waveguide laser in erbium-diffusion-doped LiNbO3

Monolithically integrated dbr waveguide laser and intensity modulator in erbium doped linbo3

DBR STRIPE WAVEGUIDE LASERS IN ERBIUM-DIFFUSION-DOPED LiNbO3

First monolithically integrated DBR waveguide laser and Mach-Zehnder intensity modulator in erbium-doped LiNbO/sub 3/