Opnext Japan, Inc.

Hitachi, Ltd.

Kenji Yoshimoto

Naoki Matsushima

Hiroyasu Sasaki

Toshiaki Takai

Masanobu Okayasu

Hiroshi Yamamoto

Osamu Kagaya

Michihide Sasada

Hideyuki Kuwano

Tetsuya Aoki

Koichiro Tonehira

Takaharu Arai

Hayato Minekawa

To detect a wavelength drift of laser light with no error, an optical transmission module () includes: a laser diode (); a laser temperature calculation section () for detecting the temperature of the laser diode () that monotonously increases with respect to a wavelength of the laser light; a wavelength calculation section () for detecting a transmittance of the laser light incident on an etalon filter () whose transmittance periodically varies with respect to the wavelength of the incident light, and a laser wavelength corresponding to the transmittance; and a wavelength error obtaining section () for detecting a wavelength error (wavelength drift), from a target wavelength, of the laser light output from the laser diode (), based on the temperature detected by the laser temperature calculation section () and the laser wavelength detected by the wavelength calculation section ().

Optical transmission module, wavelength monitor, and wavelength drift detection method

To provide a small-sized and reliable optical module in which a light emitting element and an optical function element respectively remarkably different in a coefficient of thermal expansion are mounted in the same casing, in the invention, the optical function element is mounted on the casing made of first material substantially equal in a coefficient of thermal expansion to the optical function element, a light emitting element unit including the light emitting element (for example, a thermoelectric module over which the light emitting element is mounted) is mounted on a member (base material) made of second material different from the first material and matched with the light emitting element unit in a coefficient of thermal expansion, and the member is, for example, embedded in the bottom of the casing.

Optical module

The present invention provides an optical transmission module configured such that a driver IC chip to drive a semiconductor laser device, a first insulation plate having the semiconductor laser device mounted thereon and a coupling optical component are mounted in this order, a thin film inductor element and thin film resistor element which are connected in parallel are formed on a second insulation plate and a bias current is supplied to the semiconductor laser device via this LR element.

Optical transmission module

The present invention provides a compact, highly reliable optical module in which a light-emitting element and optical modulator element that differ from each other in thermal expansion coefficient are mounted in one casing. In the optical module having a differential thermal expansion coefficient less than 5&#xd7;10[1/K] between the light-emitting element and the casing, and a differential thermal expansion coefficient of at least 5&#xd7;10[1/K] between the optical modulator element and the casing, a section at which the optical modulator element and the casing are fixed is equal to or less than 10 mm wide in the direction of an optical axis.

To provide economical high-speed optical communications through an optical module a silicon substrate with a ball lens and semiconductor luminescence element mounted thereon, and a laser driver IC are provided. A silicon subassembly includes a silicon substrate with a pyramidal cavity etched into the substrate near its edge. A ball lens is precision-mounted in the pyramidal cavity by bonding it at multiple points. This provides a high-strength connection and a small, inexpensive silicon substrate. Also provided on the silicon substrate is a semiconductor luminescence element and a slit on the opposite side of the ball lens. The slit enables collimated light emitted from the ball lens to be optically coupled without being blocked or reflected by the substrate. The semiconductor luminescence element and its laser driver IC are placed in close proximity to each other, and ribbon wires are kept short (approximately 300 &mgr;m) to reduce signal line impedance mismatch for high-speed transmission.

Growing community of inventors

Yokohama, Japan

Kenji Yoshimoto