Description of Business	12 Months Ended
Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Business Overview EMCORE Corporation together with its subsidiaries (referred to herein as the “Company,” “we,” “our,” or “EMCORE”), was established in 1984 as a New Jersey corporation. The Company became publicly traded in 1997 and is listed on the Nasdaq stock exchange under the ticker symbol EMKR. EMCORE pioneered the linear fiber optic transmission technology that enabled the world’s first delivery of Cable TV directly on fiber, and today is a leading provider of advanced Mixed-Signal Optics products that enable communications systems and service providers to meet growing demand for increased bandwidth and connectivity. The Mixed-Signal Optics technology at the heart of our broadband communications products is shared with our fiber optic gyros and inertial sensors to provide the aerospace and defense markets with state-of-the-art navigations systems technology. With both analog and digital circuits on multiple chips, or even a single chip, the value of Mixed-Signal device solutions is often far greater than traditional digital applications and requires a specialized expertise held by EMCORE which is unique in the optics industry. We currently have one reporting segment: Fiber Optics. Sale of Photovoltaics and Digital Products Businesses In the fiscal year ended September 30, 2015, EMCORE completed the sale of the Company's Photovoltaics Business to SolAero Technologies Corporation (“SolAero”) pursuant to the Asset Purchase Agreement (the “Photovoltaics Agreement”) under which SolAero acquired substantially all of the assets, and assumed substantially all of the liabilities, primarily related to or used in connection with the Company's Photovoltaics Business, including EMCORE's subsidiaries EMCORE Solar Power, Inc. and EMCORE IRB Company, LLC (collectively, the “Photovoltaics Business” and, the sale of the Photovoltaics Business, the “Photovoltaics Asset Sale”), for $149.9 million in cash. In the fiscal year ended September 30, 2015, EMCORE completed the sale of the Company's telecommunications business (the “Digital Products Business”) to NeoPhotonics Corporation, a Delaware corporation (“NeoPhotonics”), pursuant to the Asset Purchase Agreement (the “Digital Products Agreement”), under which NeoPhotonics acquired certain assets, and certain liabilities, related to the Company's Digital Products Business for an aggregate purchase price of $17.5 million. On January 2, 2015, EMCORE completed the sale of the Digital Products Business for $1.5 million in cash and a promissory note in the principal amount of $16.0 million (the "Promissory Note"). On April 16, 2015, EMCORE and NeoPhotonics entered into an agreement to adjust the purchase price for the Digital Products Business, resulting in an adjusted balance of the Promissory Note of $15.5 million. On April 17, 2015, NeoPhotonics paid in full the outstanding balance of the Promissory Note of $15.5 million, plus accrued interest of $0.2 million. No Photovoltaics Business or Digital Products Business assets or liabilities that were sold remain on the consolidated balance sheet as of September 30, 2017 or September 30, 2016. The financial results of the Photovoltaics Business and the Digital Products Business are presented as “discontinued operations” on the consolidated statements of operations and comprehensive income for the fiscal years ended September 30, 2017, 2016 and 2015. See Note 5 - Discontinued Operations for additional information. The notes to our consolidated financial statements relate to our continuing operations only, unless otherwise indicated. Liquidity and Capital Resources Historically, we have consumed cash from operations and until recently, in most periods we have incurred operating losses from continuing operations. We have managed our liquidity position through the sale of assets, and cost reduction initiatives, as well as from time to time in prior periods, borrowings from our Credit Facility and capital markets transactions. On December 10, 2014, we completed the sale of our Photovoltaics Business for 150.0 million in cash prior to working capital adjustments of $0.1 million. On January 2, 2015, we completed the sale of our Digital Products Business for $1.5 million in cash and an adjusted Promissory Note balance of $15.5 million. On April 17, 2015, NeoPhotonics paid in full the outstanding balance of the Promissory Note of $15.5 million, plus accrued interest of $0.2 million. On June 15, 2015, we completed the modified "Dutch auction" tender offer (the "Tender Offer") and purchased 6.9 million shares of our common stock at a purchase price of $6.55 per share, for an aggregate cost of $45.0 million excluding fees and expenses. Repurchased common stock was recorded to treasury stock. The Company incurred costs of $0.7 million in connection with the Tender Offer, which were recorded to treasury stock. As of September 30, 2017, cash and cash equivalents totaled $68.3 million and net working capital totaled approximately $103.0 million. Net working capital, calculated as current assets minus current liabilities, is a financial metric we use which represents available operating liquidity. For the fiscal year ended September 30, 2017, we earned net income of $8.2 million.

Description of Business

Business Overview

EMCORE Corporation together with its subsidiaries (referred to herein as the “Company,” “we,” “our,” or “EMCORE”), was established in 1984 as a New Jersey corporation. The Company became publicly traded in 1997 and is listed on the Nasdaq stock exchange under the ticker symbol EMKR. EMCORE pioneered the linear fiber optic transmission technology that enabled the world’s first delivery of Cable TV directly on fiber, and today is a leading provider of advanced Mixed-Signal Optics products that enable communications systems and service providers to meet growing demand for increased bandwidth and connectivity. The Mixed-Signal Optics technology at the heart of our broadband communications products is shared with our fiber optic gyros and inertial sensors to provide the aerospace and defense markets with state-of-the-art navigations systems technology. With both analog and digital circuits on multiple chips, or even a single chip, the value of Mixed-Signal device solutions is often far greater than traditional digital applications and requires a specialized expertise held by EMCORE which is unique in the optics industry.

We currently have one reporting segment: Fiber Optics.

Sale of Photovoltaics and Digital Products Businesses

In the fiscal year ended September 30, 2015, EMCORE completed the sale of the Company's Photovoltaics Business to SolAero Technologies Corporation (“SolAero”) pursuant to the Asset Purchase Agreement (the “Photovoltaics Agreement”) under which SolAero acquired substantially all of the assets, and assumed substantially all of the liabilities, primarily related to or used in connection with the Company's Photovoltaics Business, including EMCORE's subsidiaries EMCORE Solar Power, Inc. and EMCORE IRB Company, LLC (collectively, the “Photovoltaics Business” and, the sale of the Photovoltaics Business, the “Photovoltaics Asset Sale”), for $149.9 million in cash.

In the fiscal year ended September 30, 2015, EMCORE completed the sale of the Company's telecommunications business (the “Digital Products Business”) to NeoPhotonics Corporation, a Delaware corporation (“NeoPhotonics”), pursuant to the Asset Purchase Agreement (the “Digital Products Agreement”), under which NeoPhotonics acquired certain assets, and certain liabilities, related to the Company's Digital Products Business for an aggregate purchase price of $17.5 million. On January 2, 2015, EMCORE completed the sale of the Digital Products Business for $1.5 million in cash and a promissory note in the principal amount of $16.0 million (the "Promissory Note"). On April 16, 2015, EMCORE and NeoPhotonics entered into an agreement to adjust the purchase price for the Digital Products Business, resulting in an adjusted balance of the Promissory Note of $15.5 million. On April 17, 2015, NeoPhotonics paid in full the outstanding balance of the Promissory Note of $15.5 million, plus accrued interest of $0.2 million.

No Photovoltaics Business or Digital Products Business assets or liabilities that were sold remain on the consolidated balance sheet as of September 30, 2017 or September 30, 2016. The financial results of the Photovoltaics Business and the Digital Products Business are presented as “discontinued operations” on the consolidated statements of operations and comprehensive income for the fiscal years ended September 30, 2017, 2016 and 2015. See Note 5 - Discontinued Operations for additional information. The notes to our consolidated financial statements relate to our continuing operations only, unless otherwise indicated.

Liquidity and Capital Resources

Historically, we have consumed cash from operations and until recently, in most periods we have incurred operating losses from continuing operations. We have managed our liquidity position through the sale of assets, and cost reduction initiatives, as well as from time to time in prior periods, borrowings from our Credit Facility and capital markets transactions.

On December 10, 2014, we completed the sale of our Photovoltaics Business for 150.0 million in cash prior to working capital adjustments of $0.1 million.

On January 2, 2015, we completed the sale of our Digital Products Business for $1.5 million in cash and an adjusted Promissory Note balance of $15.5 million. On April 17, 2015, NeoPhotonics paid in full the outstanding balance of the Promissory Note of $15.5 million, plus accrued interest of $0.2 million.

On June 15, 2015, we completed the modified "Dutch auction" tender offer (the "Tender Offer") and purchased 6.9 million shares of our common stock at a purchase price of $6.55 per share, for an aggregate cost of $45.0 million excluding fees and expenses. Repurchased common stock was recorded to treasury stock. The Company incurred costs of $0.7 million in connection with the Tender Offer, which were recorded to treasury stock.

As of September 30, 2017, cash and cash equivalents totaled $68.3 million and net working capital totaled approximately $103.0 million. Net working capital, calculated as current assets minus current liabilities, is a financial metric we use which represents available operating liquidity. For the fiscal year ended September 30, 2017, we earned net income of $8.2 million.